Thirty years of Sequence Stratigraphy:
Applications, Limits and Prospects
2 October 2006
Bari (Italy)
WORKSHOP ABSTRACT
VOLUME
Organization:
Luisa Sabato (convener)
TST - HST
Luigi Spalluto
HST
HST
Marcello
Tropeano
LST
TST
HST TST
SMST
sb1
FSST
Financial
incised support:
valley
TST di Barisb2
Dipartimento
di Geologia e Geofisica - Università
fills
FSST
sb1
Amministrazione d’Ateneo - Università diLST
Bari
GeoSed - Associazione Italiana di Geologia del Sedimentario
sb1
Dottorato in Scienze della Terra - Università di Bari
older sequence
Regione Puglia - Assessorato Mediterraneo
Provincia di Bari - Assessorato Cultura
Thirty years of Sequence Stratigraphy: Applications, Limits and Prospects - 2 October 2006 - Bari - Italy
8.30 - 9.00
- Registration.
9.00- 9.30
- Welcome to participants and short presentation of the workshop.
E. Lofrumento (Preside Facoltà di Scienze)
G. Zito (Direttore Dipartimento di Geologia e Geofisica)
L. Sabato (Convener)
INVITED TALKS
chairman: N. Ciaranfi
9.30 - 10.00 B. Haq - Hystorical development of sequence stratigraphy.
10.00 - 10.30 B. Haq - The new Global Cycles Chart.
10.30 - 11.00 B. D’Argenio & V. Ferreri - Cyclo- and sequence-stratigraphy: the case of
shallow water carbonates.
11.00 - 11.20
1
1
3
coffee break ------- (poster session) --------
chairman: P. Pieri
11.20 - 11.50 D. Masetti - Upper Triassic and Lower Jurassic thickening-upward, subtidal
cycles in the Southern Alps: from the ramps to the lagoons.
9
11.50 - 12.20 L. Simone & G. Carannante - Foramol (temperate-type) vs chlorozoan
(tropical-type) carbonate platforms: depositional dynamics
and architecture of the related depositional systems.
19
12.20 - 12.50 G.G. Ori - Sequence stratigraphy of deltaic and shallow lacustrine deposits,
Juventae Chasma (Mars).
21
12.50 - 13.50
13.50 - 14.30
lunch
-----------------------------------
poster session
chairman: A. Amorosi
14.30 - 15.00 F. Chiocci - Depicting correlative conformities on high-resolution seismic data.
23
15.00 - 15.30 F. Trincardi - Sediment routing, relative sealevel fluctuations and the growth of
Quaternary depositional sequences in the Central Mediterranean.
25
15.30 - 16.00 S. Milli - The sequence stratigraphy of the Quaternary successions: implications
about the origin and filling of incised valleys and the mammal fossil record.
27
16.00 - 16.20
coffee break ------- (poster session) -------
chairman: L. Simone
16.20 - 16.50 A. Amorosi - Application of sequence stratigraphic concepts to a highly
subsiding basin: the example of the Po Plain.
29
16.50 - 17.20 R. Bersezio - Aquifer characterization and hydrostratigraphy of alluvial
sediments: taking advantage of sequence stratigraphy methods.
33
17.20 - 17.50 A. Milia - Sequence stratigraphy in volcanic settings: examples from the
Campania Margin.
35
17.50 - 18.20 M. Tropeano - The Calcarenite di Gravina Formation in Matera: a good training
for sequence stratigraphy.
37
18.20 - 19.00 - B. Haq & L. Sabato - Discussion and workshop closure.
Thirty years of Sequence Stratigraphy: Applications, Limits and Prospects - 2 October 2006 - Bari - Italy
POSTER PROGRAMME
A. Albianelli, A. Bertini, C. Lombardi, M. Moretti, G. Napoleone & L. Sabato - Cyclicity in the
lower and middle Pleistocene San Lorenzo lacustrine succession of the Sant’Arcangelo
Basin (Southern Apennines, Italy): magnetic, palynologic and sedimentary signals.
41
A. Cilumbriello, L. Sabato, M. Tropeano, S. Gallicchio, A. Grippa & P. Pieri - Stratigraphic
arrangement of the “Regressive coastal deposits” of the Bradanic Trough (Basilicata,
southern Italy): subsidence, uplift, and high-frequency sea-level changes.
43
D. De Benedictis - The interplay amongst trophic regime, carbonate feedback system
and changes in stratigraphic accommodation space: an investigation based on the
palaeoecological analysis of the microbenthic assemblages in two case studies of the
Early Cretaceous shallow-water carbonates.
47
M. Delle Rose - Some features of the Pliocene – Lower Pleistocene sequence of the
southeastern Salento.
49
M. Delle Rose & F. Resta - Stratigraphic and sedimentological insights about the Capo San
Gregorio breccias and conglomerates (South Salento).
53
A. Irace, M. Natalicchio, P. Clemente, S. Trenkwalder, P. Mosca, R. Polino, D. Violanti &
D.A. De Luca - Stratigraphic architecture and deep hydrostratigraphy in the Pliocene to
Holocene deposits of the Western Po Plain.
57
S. Longhitano - Sequence stratigraphy of the Potenza Basin Pliocene coarse-grained deltas
(southern Italy): recognition of medium- and high-frequency relative sea-level oscillations
during the sedimentation.
61
G.G. Ori - Continental sequences in Sahara dominated by climatic changes.
65
M. Pistis, A. Loi, F. Leone, E. Melis, A.M. Caredda & M.P. Dabard - Architettura deposizionale
degli accumuli a minerali pesanti (placers): esempio nell’Ordoviciano della Sardegna e
della Bretagna - (Stacking Pattern of heavy minerals enrichment (placers):example of the
Ordovician of Sardinia and Brittany).
67
L. Spalluto - The Upper Jurassic-Lower Cretaceous carbonate platform succession of the
western Gargano Promontory: description and hierarchical organization of high-frequency
depositional sequences.
73
M. Tropeano, P. Pieri, L. Pomar & L. Sabato - Base level vs sea level in shallow-marine clastic
systems: con”sequence” stratigraphy.
77
M. Zecchin - The “aggradational highstand systems tract” (AHST): definition and key
characteristics.
79
M. Zecchin, G. Brancolini, F. Donda, F. Rizzetto & L. Tosi - Sequence stratigraphy of Holocene
deposits in the Venice area based on high-resolution seismic profiles.
81
PARTICIPANTS - INDEX
84
Thirty years of Sequence Stratigraphy:
Applications, Limits and Prospects
INVITED TALKS
TST - HST
HST
TST
incised valley
fills
HST
HST TST
FSST
LST
SMST
TST
LST
sb1
older sequence
FSST
sb2
sb1
sb1
Thirty years of Sequence Stratigraphy: Applications, Limits and Prospects - 2 October 2006 - Bari - Italy
HISTORICAL DEVELOPMENT OF SEQUENCE STRATIGRAPHY
Bilal U. Haq
National Science Foundation, Arlington, VA 22230, USA
Since the conceptual models of Sequence
Stratigraphy first began to be employed
over thirty years ago, they have served the
exploration industry well in both pre-drill
predictions and down-stream field development.
This paradigm, nevertheless, has entered a
new phase and these concepts are being
applied at ever-increasing higher resolution
and in multiple settings, i.e., passive Atlantictype margins, active margins, margins without
point-sourced sediments, and in deep water
and non-marine systems. Much of the new
research in the past several years has been
focused on higher resolution studies.
the prediction of reservoir, source and seal
facies (e.g., channel fills, sediment waves,
overbank spillover and crevasse splays, debris
flows, etc.).
Complementary to the use sequence
stratigraphic models is the utility of the global
cycle chart which allows chronostratigraphic
synthesis and facilitates first-order global
correlations. It also allows the exploitation
of global depositional trends as an effective
exploration tool. Examples of the latter include,
prediction of: the duration and magnitude of
unconformities, duration and magnitude of
condensed sections, extent of the vertical
and lateral migration of facies and the severity
of the subareal exposure during lowstand
times. Duration of the exposure to erosive and
corrosive elements is of particular predictive
utility in evaluation reservoir quality in
carbonates.
As the industry increases its exploration
efforts in deeper water, there is a new
urgency to understand the seismic facies and
geomorphological attributes of the basin floor
beyond the foot of the slope. Here, again,
sequence stratigraphic models are helping in
THE NEW GLOBAL CYCLE CHART
Bilal U. Haq
National Science Foundation, Arlington, VA 22230, USA
A meaningful representation of eustatic
changes of the past is fundamental to all
sedimentary geology and stratigraphy. Over
the last two decades a significant amount of
worldwide stratigraphic, tectonic and isotopic
data has accumulated that sheds new light on
the makeup of stratigraphic sequences, their
relationship to various causal mechanisms
and the timing and magnitude of regional
base-level changes. More significantly these
considerations have revealed many of the
underlying problems in interpreting stratigraphic
and stable-isotopic data in terms of sea-level
fluctuations. One insightful conclusion of these
deliberations has been that while it’s feasible
to pin down the timing of major base-level
changes, it will remain less likely that we can
constrain the magnitude of these changes
meaningfully, because interpretations based on
physical and isotopic data are often at variance.
The presentation will briefly review the problems
associated with various types of data in terms
of base-level change interpretations, especially
in obtaining a measure of ice-volume changes
from oxygen-isotopic data and estimating
the extent of rises and falls from physical
data. In view of these issues the presentation
will then enumerate the most reasonable
approach for reconstructing a eustatic model
for the Mesozoic and Cenozoic and discuss its
inherent variable measure of accuracy based
of the quality of data available for various time
intervals. The concept of designating reference
sections for eustatic events (that most closely
represent the global mean for specific time
intervals) is also introduced and the resultant
sea-level curve is exemplified, together with
estimates of magnitude of change (with their
limits of accuracy) for each eustatic event.
The new sea-level curves will thus represent
a state-of-the-art and major improvement over
those published earlier.
1
2
Thirty years of Sequence Stratigraphy: Applications, Limits and Prospects - 2 October 2006 - Bari - Italy
CYCLO- AND SEQUENCE-STRATIGRAPHY: THE CASE OF SHALLOW WATER
CARBONATES
Bruno D’Argenio1,2 and Vittoria Ferreri1
1
Dipartimento di Scienze della Terra, Università degli Studi di Napoli “Federico II”, Largo
San Marcellino 10, 80138 Naples, Italy. e-mail: [email protected]
2
Istituto per l’Ambiente Marino Costiero, CNR, Calata Porta di Massa, Porto di Napoli,
80133 Napoli, Italy. e-mail: [email protected]
of shallow- and deep-water origin, has yielded a
rich information about even minute modification
in their depositional environment that, in turn,
reveals systematic (cyclic) changes in the
correspondent
climatic-palaeoceanographic
system, at a scale well beyond the resolution
of the biostratigraphy (Strasser et al., 2001;
D’Argenio et al., 2004a,b).
Here we briefly report about our studies
carried out in southern Italy and Montenegro
on Cretaceous shallow-water carbonates
to understand: (a) the role of climatic and
correspondent eustatic oscillations in the
development of the above carbonates, as
well as (b) in their hierarchical organization
in elementary cycles and their grouping, and
(c) their genetic relationships with the CrollMilanković orbital periodicities, once the
autocyclic (local) component of the sedimentary
signal has been removed (Brescia et al., 1996,
Tagliaferri et al., 2001). Moreover, being largely
biogenic in nature, the carbonate deposits of
the shallow (sub)tropical seas were produced
at different rates and with changing mud/
grains ratios, giving rise to variable sediment
thickness per unit of time. At present, the above
Cretaceous rocks outstandingly outcrop in the
Periadriatic Region as thick stratal successions
that disclose a multiscale sequencecyclostratigraphy configuration, well evident
in the composite mode of their aggradational
patterns, laterally consistent also at >100 km
distance (Amodio et al., 2003; D’Argenio et al.,
1999; 2004a; D’Argenio and Ferreri, 2003).
Abstract
Textures and early diagenetic features
of carbonate-platform deposits from the
Cretaceous of southern Italy and Montenegro
(Periadriatic Region) have been analysed
at centimetre to decimetre scale for a total
thickness of about 1500m along well exposed
sections or using well cores. In their vertical
organization, it was recognised a hierarchy
of cycles (3-5 elementary cycles, grouped
in a bundle, and 2-4 bundles grouped in
a superbundle). High-frequency eustaticclimatic changes, linked to the Earth’s orbital
perturbations, are considered at the origin of this
hierarchy, where the elementary cycles record
the precession and/or the obliquity periodicities
and the bundles and superbundles the shortand long-eccentricity, respectively. These
orbital cycles are superimposed on lowerfrequency cycles (Trangressive/Regressive
Facies Trends, TRFTs), commonly made
up of 2-5 superbundles. Even if the studied
deposits do not show evident progradational
and retrogradational geometries, pertaining
to internal areas of carbonate platforms, their
well ordered aggradational cyclostratigraphic
configuration allow the stratal (cycle)
composition and thickness to be considered as
proxies of eustatic changes. On this assumption
the superbundles and the TRFTs were
interpreted in terms of depositional sequence
equivalents and used for high precision,
regional- to global-scale correlations as well
as to assemble orbital chronostratigraphic
diagrams which quantify the minimum time
required for each succession to stack up.
Cyclostratigraphy
Mesozoic-Paleogene
carbonate
platform
sequences, widespread in the Mediterranean
Region, developed for more than 200 my on
both sides of the oceanic Tethys, forming large
(up to 104 km2) and thick (even >3-4 x 103m)
sedimentary bodies, which are well stratified
and characterized by high rate of sedimentation
(from <30 up to >100 m/my). The carbonate
platforms contain minor or no terrigenous
admixtures and were highly sensitive to short-
Introduction
Concepts on high-frequency cyclicity dominated
by conditions external to the depositional
environments (allocyclicity) are nowadays
widely accepted (e.g. De Boer and Smith,
1994; House and Gale, 2005; D’Argenio et al.,
2004b). It has been also shown in the last few
years that high-resolution analysis (0,1–1,0 cmscale data) of several Phanerozoic sequences,
3
term climatic and oceanographic variations, as
well as to high-frequency sea-level oscillations
(Fig.1).
inclination and declination) measured in the
Hauterivian-Barremian of southern Apennines
(Iorio et al., 1996). Finally, The above high
frequency cycles are superimposed on lower
frequency Transgressive/Regressive Facies
Trends (T/RFTs, Fig.2) ranging from 800 to
2000 ky.
In the last years we have measured and
sedimentologically studied at centimeter
scale a total of about 1500 m of Cretaceous
carbonate platform strata from southern Italy
and Montenegro. The study has been carried
out on several wholly exposed sections or long
bore cores, (Amodio, 2006; Buonocunto et al.
1999, 2002; D’Argenio et al., 1997, 1999, 2004a;
Sandulli, 2004; Wissler et al., 2004;). For each
studied succession microstratigraphic analysis
has shown a number of lithofacies organized
in lithofacies associations suggesting, on the
whole, inner settings of a large carbonate
platform domain (from peritidal-supratidal to
open platform and shallow ramp). The stacking
pattern of depositional ad early diagenetic
characteristics reveals a hierarchichy of cycles
(3-5 elementary cycles, each commonly
corresponding to a single bed, are grouped in
a bundle; in turn 2-4 bundles are grouped in a
superbundle). While the elementary cycles are
related to the precession and/or to the obliquity
periodicities, bundles and superbundles record
the short- and long-eccentricity Earth’s orbital
cycles, respectively. This interpretation has
been confirmed by mathematical treatment of
the sedimentary data (lithofacies and related
early meteoric fabric thickness) carried out at
cm-scale on numerous Cretaceous carbonate
platform successions of southern Italy (Longo
et al., 1994; Brescia et al., 1996; Tagliaferri
et al., 2001), as well as by the analysis of the
magnetostratigraphic parameters (remanent
Sequence Cyclostratigraphy and LongDistance Correlation
Aggradational sequence-stratigraphy.
The above well ordered aggradational
sequence-cyclostratigraphic
configuration
enables the stratal (cycle) composition and
thickness of the shallow-water carbonates to be
considered as proxies of (a) the progradational
(thinning)–retrogradational (thickening) mode
and geometries of the stratal successions, as
well as of (b) the related climatic conditions and
eustatic ranges (D’Argenio et al., 1999; 2003).
On the basis of the notions and approaches
here outlined, series of strata, unique in their
organization and tied to the Croll-Milanković
orbital signals, may be constrained in terms
of sequence-cyclostratigraphy, considering
the superbundles as depositional sequences
and their upper limits, marked by downwards
penetrating, early meteoric diagenetic overprint,
as Sequence Boundaries (SB). Within each
superbundle the most open marine lithofacies
indicates location of its maximum flooding
surface (mfs). The choise of the superbundles
(about 400-ky cycles) as depositional
sequence equivalents was suggested by
their higher probability to be preserved in
the sedimentary record, even if some of their
elementary cycles (and/or bundles) may be
Fig.1. Cartoon showing carbonate platform interior deposits developing with a prevailing aggradational
mode (right). Here lateral variations in bedding geometry, even if of km-extent, are very gradual and
only the vertical strata organization carries evidence of eustatic oscillations (see also Fig.3) while
typical retro-progradational geometries develop along the marginal sectors of the platform (centre)
sloping into the aggradational basin settings (left).
4
Fig.2. Example of hierarchical cycle organization and of environmental changes primarily produced
by climatic and eustatic response to Earth’s orbital cyclicity at Serra Sbregavitelli (Campania
Apennines). (a) Elementary cycles (about 20-40 ky cycles); to the right T indicates transgressive
trends and R regressive trends; em: the horizontal line separates the marine interval (above) from the
emersion-related cap topping the cycles (below); (b) bundles (about 100-ky cycles); (c) superbundles
(about 400-ky cycles); (d) T/RFTs, Transgressive/Regressive Facies Trends (about 1.2-2 my each).
Here two climatic and eustatic conditions are suggested by the organisation of the elementary cycles:
a first condition of wider eustatic range (Upper Hemicycle), where the subtidal domains prevail , a
second of smaller eustatic range (Lower Hemicycle), where peritidal domains dominate.
the studied sequences (on biostratigraphic,
isotopic and/or paleomagnetic bases) to the
standard time scales (D’Argenio et al., 2004a;
Ferreri et al., 2004; Iorio et al., 1998, 2001;
Wissler et al., 2004). This allows an eccentricityprecision (≤ 400 ky) to be also attained in longdistance correlation (≥ 500 km present-day
separation) among successions laid down
under the same or different sedimentary
regimes, like carbonate platforms and pelagic
basins (e.g. D’Argenio et al., 2004a).
Here the tie-points used as stratigraphic
markers in global correlations are (1) the
Valanginian/Hauterivian boundary individuated
in the Sferracavallo (Palermo Mountains,
north-western Sicily) and in the San Lorenzello
(Matese Mountains, Campania Apennines)
successions,
(2)
the
Barremian/Aptian
boundaries individuated in the Monte Raggeto
succession (Monte Maggiore Mountains,
Campania Apennines) as well as in the
S.Maria 4 Agip core (Maiella Mountain, central
Apennines), (3) the Aptian/Albian boundary
individuated at Monte Raggeto as well as at
Serra Sbregavitelli (Matese Mountains) and at
Monte Faito (Picentini Mountains, Campania
Apennines). In particular, in the Aptian-Lower
missing, due to the lower accommodation at
the superbundle limits. Accordingly, based on
the stacking pattern of the superbundles, also
the Transgressive/Regressive Facies Trends
may be considered in terms of depositional
sequence equivalents, comparable with the
third order cycles (sensu Haq et al., 1987; Vail
et al., 1991; Hardenbol et l., 1998)
Regional correlation.
Using appropriate biostratigraphic markers,
comparison of the above cycles, considered
in terms of depositional sequence equivalents,
allows high resolution physical correlations
(precision ≤100 ky) to be delineated at regional
scale among the studied Lower Cretaceous
coeval sections (present-day distance from
each other up to >500 km) and lateral thickness
variations to be restored at level of discrete
(even <10 m) stratal intervals that change
according to their depositional environment
(D’Argenio et al., 1999; 2004a; Amodio et al.,
2003; Fig.3).
Global-scale correlation.
Global correlations have also been proposed
between our Transgressive/Regressive Facies
Trends and the third order sequences of
Hardenbol et al. (1998), concurrently anchoring
5
Albian of Serra Sbregavitelli, M. Raggeto and
M. Faito such correlation has been corroborated
by high-resolution carbon-isotope stratigraphy.
From the integrated cyclostratigraphic-isotopic
approach (D’Argenio et al., 2004a) a good
correspondence emerges (a) from carbonisotope longer trends between the pelagic and
the carbonate platform domains as well as (b)
between the Transgressive/Regressive Facies
Trends singled out in the Periadriatic Region
and the third order eustatic cycles already
known for the corresponding Cretaceous time.
are based on the following assumptions:
(a) a superbundle in cyclostratigraphy is
the equivalent of a depositional sequence
in sequence stratigraphy, (b) the maximum
flooding surfaces of the time-equivalent
superbundles are isochronous at the scale of
the bundles (100-ky cycles and even of the
elementary cycles in those bundles without
elementary cycle omissions); (c) the bundles
are used as chronostratigraphic units, (d)
the highest probability of omission in the
stratigraphic record (as non depositional or
erosional gaps) occurs at the boundaries of the
Trangressive/Regressive Facies Trends (T/
RFTs), where the sedimentary record suggests
the minimum accommodation space. Orbital
Orbital Chronostratigraphy
The superbundles can be also used to
assemble chronostratigraphic diagrams that
Fig 3. Cycle stacking patterns and regional organization of some Cretaceous sections studied at
cm-scale or added to restore an ideal section across the southern Apennines. Sections C, D, E1
and E2 are real (and their superbundles are represented and numbered according to D’Argenio et
al., 2004a), while sections A, B and F are ideally placed on their sides. In the upper row the sections
are reported at the same horizontal scale. Note their different thickness according to the position
in an ideal carbonate platform, where the thicker and more continuous sedimentation develops in
the open lagoonal areas (column C), decreasing in thickness and increasing in omissions towards
the more restricted lagoon sectors (columns D and E1+E2). In the lower row the correspondent
chronostratigraphy is represented. Inset: C, Serra Sbregavitelli section; D, Monte Raggeto section;
E, composite section (E1: T1-T5, Monte Tobenna section; E2: F1-F4, Monte Faito section); A, B and
6
chronostratigraphy (Fig.3) allows (a) to locate
the missing cycles (bundles) throughout the
studied successions, (b) to calculate for each
superbundle, as well as for each succession,
its average accumulation rate regardless of
gaps occurring in the sedimentary record and
(c) to estimate the minimum time required for
each succession to accumulate (D’Argenio
et al.,1997; 1999; 2004a). For example, a
time span of 2.9 my has been estimated for
the Valanginian-Hauterivian interval of the S.
Lorenzello succession (Ferreri et al., 2004)
whilst a time duration of 8.4 my has been
evaluated for the whole Aptian stage of M.
Raggeto (D’Argenio et al., 2005).
Brescia M., D’Argenio B., Ferreri V., Pelosi N.,
Rampone S. and Tagliaferri R., 1996, Neural net
aided detection of astronomical periodicities in
geologic records. Earth Planet. Sci. Lett., 139,
33-45.
Buonocunto F.P., D’Argenio B., Ferreri V. and
Sandulli R., 1999, Orbital cyclostratigraphy and
sequence stratigraphy of Upper Cretaceous
platform carbonates at Monte Sant’Erasmo,
southern Apennines – Italy. Cret. Research, 20,
81-95.
Buonocunto F.P., Sprovieri M., Bellanca A.,
D’Argenio B., Ferreri V., Neri R. and Ferruzza
G., 2002, Cyclostratigraphy and high-frequency
carbon-isotope fluctuations in Upper Cretaceous
shallow-water carbonates, southern Italy.
Sedimentology, 49, 1331-1337.
D’Argenio B., Amodio S., Ferreri F. and Pelosi
N., 1997, Hierarchy of high frequency orbital
cycles in Cretaceous carbonate platform strata.
Sedimentary Geology, 113, 169-193.
D’Argenio B. and Ferreri V., 2003, Sequence
stratigraphy, a methodology for long-distance
correlation and orbital chronostratigraphy. AAPG
International Conference, Barcelona, Spain, CDRom, 6pp.
D’Argenio B., Ferreri V., Amodio S., 2005, Aptian
geochronology
from cyclostratigraphy
of
shallow-marine carbonates. 7th Int. Symposium
on the Cretaceous, Neuchâtel, Switzerland, Abs.
Vol., p.64-65.
D’Argenio B., Ferreri V. Weissert H., Amodio
S., Buonocunto F.P., Wissler L., 2004a, A
multidisciplinary approach to global correlation
and geochronology. The Cretaceous shallowwater carbonates of southern Appenines,
Italy, in D’Argenio B., Fischer A.G., Premoli
Silva I., Weissert H. and Ferreri V., eds.,
Cyclostratigraphy: Approaches and case
histories: SEPM, Spec. Publ., 81, 103-122.
D’Argenio B., Fischer A.G., Premoli Silva I., Weissert
H., Ferreri V. (Eds.), 2004b, Cyclostratigraphy.
Approaches and case histories. SEPM Spec.
vol. 81, pp. 1-311.
D’Argenio B., Ferreri V., Raspini A., Amodio S.,
Bounocunto F.P., 1999, Cyclostratigraphy of a
carbonate platform as a tool for high-precision
correlation. Tectonophysics, 315, 357-385.
De Boer P.L. and Smith D.G., eds, 1994, Orbital
forcing and cyclic sequences. Blackwell Scientific
Publ., IAS, Spec. Publ., 19, 559 pp.
Ferreri V, D’Argenio B., Amodio S., Sandulli R., 2004,
Orbital chronostratigraphy of the ValanginianHauterivian boundary. A cyclostratigraphic
approach, in D’Argenio B., Fischer A.G.,
Premoli Silva I., Weissert H. and Ferreri V.,
eds., Cyclostratigraphy: Approaches and case
histories: SEPM, Spec. Publ. 81, 151-166.
Fischer A.G., 1991, Orbital cyclicity in Mesozoic
strata, in Einsele G., Ricken W. and Seilacher
A., eds., Cycles and Events in Stratigraphy:
Springer-Verlag, Berlin, 48-62.
Hardenbol J., Thierry J., Farley M.B., Jacquin T., de
Final Remarks
Changes in facies and thickness recorded
in Cretaceous carbonate platform strata of
the Periadriatic Region are mainly allocyclic
in nature and controlled by variable eustatic
oscillations modulated by the climatic system,
via Earth’s orbital cyclicity.
Based on their cyclic stacking patterns, shallowwater carbonates (Fig.1) are interpreted in
terms of sequence stratigraphy (sequence
cyclostratigraphy). This allows high-precision
(≤ 100 ky) correlations to be established, and
a 2D carbonate platform lithostratigraphy to be
restored, at regional scale (Fig.3). Once such a
high-precision correlation is fitting two or more
distant sequences, a graphic and/or numerical
expression of the acquired data may be derived
and the following results obtained (Figs.2, 3):
(a) recognition of subtle gaps, otherwise hidden
(at least in their real extent) by lack of adequate
biostratigraphic evidences; (b) quantitative
measurement of the geologic time expressed
by the whole sequence, regardless from gaps
truly punctuating it (orbital chronostratigraphy);
(c) projection of these data on the standard
sea-level oscillation curves (Haq et al., 1987;
Hardenbol et al., 1998), contributing often to
increase their precision and, sometimes, to
their emendation.
References
Amodio S., 2006, Foraminifera diversity changes
and paleoenvironmental analysis. The Lower
Cretaceous shallow-water carbonates of San
Lorenzello, Campanian Apennines, southern
Italy. Facies, v.52, p.53-67.
Amodio S., Buonocunto F.P., D’Argenio B., Ferreri V.,
Gorla L., 2003, Cyclostratigraphy of Cretaceous
shallow-water carbonates. Case histories from
central southern Italy. AAPG International
Conference, Barcelona, Spain, CD-Rom, 6pp.
7
Graciansky P.C. and Vail P.R., 1998, Cretaceous
sequence chronostratigraphy, in De Graciansky
P.C., Hardenbol J., Jacquin T., Vail P.R. and
Farley M.B., eds., Mesozoic and Cenozoic
sequence stratigraphy of European basins:
SEPM (Society for Sedimentary Geology), Spec.
Publ, 60, Chart 4.
Haq B.U., Hardenbol J. and Vail P.R., 1987,
Chronology of fluctuating sea levels since the
Triassic.Science, 237, 1156-1167.
House M. and Gale S., 1995, Orbital Forcing
timescales and cyclostratigraphy. Geological
Society Spec. Pub. 85.
Iorio M, Tarling D.H., D’Argenio B. and Nardi
G., 1996, Ultra-fine magnetostratigraphy of
Cretaceous shallow-water carbonates, Monte
Raggeto, Southern Italy, in Morris A. and Tarling
D.H., eds., Paleomagnetism and Tectonics of the
Mediterranean Region, G.S. of London, Spec.
Publ. 105, 195-203.
Iorio M., Tarling D.H., D’Argenio B., 1998, The
Magnetic Polarity Stratigraphy of a Hauterivian/
Barremian carbonate sequence from Southern
Italy. Geophysical Journal International 134,
13-24.
Iorio M., Tarling D.H., D’Argenio B., 2001, Early
Cretaceous geomagnetic behaviour compared
to a computer model. Journal of Geodynamics,
32, 445-465.
Longo G., D’Argenio B., Ferreri V. and Iorio M., 1994,
Fourier evidence for high-frequency astronomical
cycles recorded in Early Cretaceous carbonate
platform strata, Monte Maggiore, southern
Apennines, Italy, in De Boer P.L. and Smith
D.G., eds., Orbital forcing and cyclic sequences:
Blackwell Scientific Publ., IAS Spec. Publ. 19,
77-85.
Sandulli R., 2004, The Barremian carbonate
platform strata of the Montenegro Dinarids
near Podgorica: a cyclostratigraphic study.
Cretaceous Research, 25, 951-967.
Strasser A., Carol M. and Gjermeni M., 2001,
The Aptian, Albian and Cenomanian of Róter
Sattel, Romandes Prealps, Switzerland: a highresolution record of oceanographic changes.
Cret. Research, 22, 173-199.
Tagliaferri R., Pelosi N., Ciaramella A., Longo
N., Milano M. and Barone F., 2001, Soft
computing methodologies for spectral analysis
in cyclostratigraphy. Comp. and Geosc., 27(5),
535-548.
Vail P.R., Audemard F., Bowman S.A., Eisner P.N.
and Perez-Cruz C., 1991, The stratigraphic
signatures
of
tectonics,
eustasy
and
sedimentology - an overview, in Einsele G.,
Ricken W. and Seilacher, A., eds., Cycles and
Events in Stratigraphy: Springer-Verlag, 617659.
Wissler L., Weissert H., Buonocunto F.P., Ferreri
V., D’argenio B., 2004, Calibration of the
Early Cretaceous time scale: a combined
chemostratigraphic
and
cyclostratigraphic
approach to the Barremian-Aptian interval. in
D’argenio B., Fischer A.G., Premoli Silva I.,
Weissert H. And Ferreri V., Cyclostratigraphy.
Approaches and case histories. SEPM Spec.
Publ. 81, pp. 123-134.
8
Thirty years of Sequence Stratigraphy: Applications, Limits and Prospects - 2 October 2006 - Bari - Italy
UPPER TRIASSIC AND LOWER JURASSIC THICKENING-UPWARD, SUBTIDAL
CYCLES IN THE SOUTHERN ALPS: FROM THE RAMPS TO THE LAGOONS
Daniele Masetti
Dipartimento di Scienze Geologiche, Ambientali e Marine dell’Università di Trieste
The examples of thickening-upward, subtidal
cycles here reported come from the mesozoic
successions of two main paleogeographicstructural units of the Mesozoic continental
margin of the Southern Alps: the Lombardy
Basin and the Trento Platform. In the Lombardy
Basin this type of cyclicity characterizes the
Upper Triassic, Rhaetic succession, while in the
Trento Platform is present in the Pliensbachian
unit of the Calcari Grigi Group, the Rotzo
Formation.
al (1994), paper to which I will refer.
1.1 The Upper Triassic succession of the
Lombardy basin
The Late Carnian to Early Jurassic succession
of the Lombardy Basin records the earliest
stages of the evolution of a passive margin that
will lead to the Liassic opening of the Jurassic
Alpine Tethys, and outcrops along a E-W belt
between the Varese and the Trento structural
highs (Fig.1). This succession consists of two
superimposed depositional systems (Jadoul
et al., 1994) and exhibits thicknesses variable
from 500 to 3500m controlled by the acyivity
of the sinsedimentary transtensive tectonics
(asymmetric rifting, Jadoul et al., 1994). The
Dolomia Principale and Aralalta Group identify
the lower depositional system, whereas the
Riva di Solto Shale, Zu Limestone and Dolomia
a Conchodon represent the upper depositional
system. Geometries and thicknesses of the
whole Late Triassic succession are shown
1.
Subtidal cyclicity in the Late Triassic
of the Lombardy Basin
The following notes are the result of a research
performed by the writer with other researchers
at the end of the eighty years and published in
Masetti et al. (1989) and Burchell et al. (1990).
The work on the cyclicity of the Upper Triassic
of the Lombardy Basin restarted together M.
Claps about ten years ago and it has been
summarized by these last authors in Jadoul et
Fig. 1- Late Carnian-Rhaetian simplified stratigraphic setting of the Lombardy basin. From Jadoul et
al., 1994.
9
Conchodon (DC, Fig.1).The whole succession
range from Late Norian to Lower Hettangian,
on the base of palynological) and foraminiferal
assemblages (Jadoul et al., 1994).
1.2 The Late Norian-Rhaetian high-frequency
cyclicity
The ARS2 and Zu consists of thickeningupward, subtidal cycles organized in different
orders of cycles. Decimetric limestonemarl couplets are arranged in metre-scale
asymmetric cycles grouped in bundles. The
bundles are assumed to be related to fourth
order cycles. We will mainly focus on vertical
pattern and thickness of these cycles. These
cycles (3 to 30m thick) consist of three parts:
a lower argillaceous unit consisting in the
ARS or marl in Zu ; a middle, rhythmic part
composed by limestone-marl “couplets”, where
the carbonate semicouplets show a general
thickening-upward arrangement. A wholly
carbonate unit marks the upper part of each
cycle. The top of each cycle is usually very
sharp, locally a partially symmetric organization
is observed. The fifth order cycles (1 to 3 m
thick in average) display a inner arrangement
similar to the described major hierarchy.
Variations in this general trend are shown in
Fig.2, according to the depth of the depositional
environment.
A-type cycle characterizes the deepest
portions of the basin, corresponding to ARS1
& 2. It is wholly muddy, generally up to 10m
thick and with shale/carbonate ratio > 10:1.
The lower part consists of black claystones
poor in skeletal, the middle unit is made by
dm-scale laminated claystone/marl couplets.
Dark micritic limestone with thin marly layers
represents the cycle top. Occasionally slumps
and paraconglomerates occur. The deposition
environment can be referred to relatively
in Fig.1. The boundary between these two
systems is linked to a crisis of the carbonate
production, in both platform and basin facies.
This sedimentary event is recorded by the
deposition of the lower Riva di Solto Shale
(ARS1, to 250 m thick) that rests directly on
the top of the drowned platforms and is present
within the basins with the highest subsidence
rates and anoxic bottoms. The unit consists
of dark, thin laminated organic-rich shales
and subordinated micritic limestones, locally
slumped, depositated in rather deep basins
well below the photic zone, inherited from the
previous paleogeography.
The lower Riva di Solto Shale is overlain by
500 to 1500 m of limestone-marls asymmetric
cycles showing an upward gradual carbonate
enrichment testifying the gradual infilling of the
basins and the shallowing-upward evolution of
the depositional environment evolving in gentle
ramps connecting the basins to the highs. This
succession contains three formations markedly
cyclic
and subdivided into the following
units: upper Riva di Solto Shale (ARS2), Zu
Limestone (Zu1, 2, 3 and 4) and Dolomia a
Fig 3 - Fourth order cycle in the Zu Limestone in
the Tremalzo locality. The black bars mark the
further subdivision in three fifth order cycles.
10
Fig 4
The palynofacies from A and B-type cycles show
a high percentage of terrestrial allochthonous
material as common background indicative of
the proximity of source areas (Jadoul et al.,
1994).
This cycle was deposited in a low-energy, deep
ramp environment, where the shallower seafloor allowed the deposition of thin bioclastic
storm-layer.
deep (below storm waves base) and poorly
oxigenated seafloor in troughs.
B-type cycle is entirely muddy and differs from
A-type on the basis of a higher carbonate/shale
ratio and the presence of thin bioclastic storm
layers. The faunal assemblage differs upward
in the cycle: the basal claystone/marls contains
small endobiontic pelecypods, the upper is
characterized by larger epibiontic pelecypods.
11
Fig. 5 - Structural and palaegeographic domains of the eastern part of the Southern Alps.
was negligible in the deepening phase and
increased during the shallowing evolution and
the consequent decreasing in accommodation
at the platform top. A subaerial exposure of
large platform areas “killed” the carbonate
factory and finally stopped the carbonate
mud supply to the basins. The same eustatic
fluctuations could be generate coarsening- and
shallowing-upward cycles in the uppermost
portion of the ramps. A mean time lenght of the
cycle of about 105 years is proposed.
C-type cycle (fig 3), typical of Zu3b, exhibits a
coarsening and shallowing-upward evolution.
The lower portion of the cycle consists of
bioturbated marls bearing a poor associations
of small pelecypods in thin storm layers.
Horizons of yellow/-reddish dolostones and
carniola-type breccias are irregularly alternated
in the marly intervals of the central part of the
cycle. Storm layers with hummocky and swaley
cross stratification are present. The top of the
cycle is sharp and marked by a metallic oxide
crust probably related to a non depositional
hiatus between two adjacent cycles.. The
increasing tempestite proximality, and the
coarsening-upward trend can be referred to a
shallowing-up evolution of these cycles. Also
the palynofacies reflect this trend. Depositional
environment can be referred to the mid-inner
sectors of a ramp.
D-type cycle shows the same trend of the Ctype, but the lower marly facies are replaced
by thin clayey interlayers. The cycle is almost
entirely typified by packstone and grainstone.
In the upper part bioclastic packstones rich in
corals, sponge, dasicladaceans, oncoids etc.
are locally present.
Metre-scale, coarsening- and shallowingupward cycles composed of subtidal
carbonates similar to C & D-type cycles have
been described in several papers. The only
interpretation of muddy asymmetric cycles
without any coarsening-upward trend (cycles
A &B, Fig. 2) was published in Masetti et al.
(1989) and Burchell et al. (1990), and applied
to the same succession previously described.
According to these authors, the asymmetric
carbonate signal was linked to sea-level
fluctuations which controlled productivity and
accommodation at the top of the platforms
representing carbonate mud productivity areas.
The basinward exportation of carbonate mud
1.3 Discussion on the origin of high frequency
cycles
The possible origin of high frequency cyclicity
include: 1) autocyclic processes, 2) allocyclic
tectonic processes, 3) Glacio-eustasy forced
by climatic cycles.
Composite, glacio-eustatic fluctuations seems
to be the only mechanism able to generate a
multi-hierarchic pattern of these Upper NorianRhaetian high-frequency cycles. The best
approach in testing for possible deterministic
control on the cyclic repetition is the application
of a composite system of spectral analysis
methodologies. In order to test the possible
presence of this type of control on the
sedimentation the spectral analysis has been
applied to the Ponte Grate section.
This section, along the Val Imagna Road, near
Ponte Grate locality, represents one of the best
exposed and complete section of the ARS 2
succession (fig 4). The base of the section is
represented by the uppermost portion of the
DP, located just below the road. Since the
deposition occurs at the top of a structural
high, the ARS1 did not deposit. The whole
section (about 60 m thick) consists of 13 fourth
order asymmetric cycles (B-type; fig 4). Each
fourth order cycle can be further subdivided in
smaller-scale fifth order cycles (Figure 4).
12
Fig.6 - Stratigraphic relationships among the Early-Middle Jurassic formations of the Trento Platform
from the Garda Lake to the Sette Comuni Plateau. The figure reports the old stratigraphic terminology
of the Calcari Grigi; the new terms are described in the text.
The processed variable is the thickness of
the successive basic, V order cycles, and the
spectral analysis computed by BlackmanTuckey algorithm shows two stable frequency
bands (Fig.4), the numeric values of which
pass the noise at the 95% confidence level
(Claps, in Jadoul et al ,1994). This analysis
shows that the basic cycle is bundled in sets
with a ratio of 2.4:1 and 10:1. In the Maximum
Entropy spectral estimator applied in Fig. 4C,
computing only the peaks which correspond to
the statistically significant intervals deduced by
the previous method, the ME spectrum gives
the following ratios: 2.3:1, 2.5:1, 8:1 and 12:1.
Both these outcomes indicate that the fourth
order cycles correspond to bundles of 2-3
fifth order cycles, and that at a higher order of
periodicity the basic cycles are also grouped in
set of 10.
The spectral analysis permit to discard
a stochastic mechanism as the process
responsible for generating the described
cyclicity. Masetti and Claps (in Jadoul et al.,
1994) therefore concluded that the statistically
significant frequency ratios of the basic cycle
could be in tune with obliquity (expressed by
basic cycles, ~41 ka) and both short- and long-
term eccentricity cycles (~100 and ~400 ka,
basic cycles multiplied by the factors 2.5 and
10) known from the Milankovitch theory. The
result of this quantitative approach suggests
a batter sensitivity of the depositional setting
to the obliquity-eccentricity signals set, but
its persistence must be proved through
further analysis. And until this is performed
the question of this cyclicity could have more
possible answers.
2. Subtidal cyclicity in the Early Jurassic of
the Trento Platform
Subtidal cyclicity similar to that described in
the ramp environment of the Late Triassic of
the Lombardy also characterizes the lagoon
deposits of the pliensbachian unit of the
Calcari Grigi Group, the Rotzo Formation. The
complete stratigraphic revision of the Calcari
Grigi unit is included in Masetti et al (1998).
2.1 The Lower Jurassic succession of the
Trento Platform and the Calcari Grigi Group
The Trento Platform covers a wide area in NE
Italy extending in a N-S direction from Verona
to Bolzano and Cortina d’Ampezzo (Fig. 5).
Eastward the Trento Platform passes into
13
the Belluno through whereas to the West it is
separated from the Lombardian basin by the
“Garda escarpment” fault-system, active during
Jurassic and Cretaceous. The stratigraphic
evolution of the Trento Platform during the
Jurassic is characterized by its sinking at the
end of the Early Jurassic: two main stages may
be thus recognized, each one represented by
a typical formation: the first phase of shallowwater sedimentation during Early-Middle Liassic
that corresponds to the thick pile of the Calcari
Grigi (Fig. 6); the second phase corresponds to
the pelagic “condensed” sedimentation on the
top of the drowned Trento platform epitomized
by the Rosso Ammonitico (Upper Bajocian to
Tithonian).
The Calcari Grigi Group, several hundred
meters thick and characterized by very rich
fossil assemblages, has been studied by many
researchers since the eighteenth century; in
the seventies this unit has been subdivided in
three informal members called Lower Member,
Middle Member and Rotzo Member (Fig. 6).
The Lower and Middle members corresponds
to the Hettangian-Sinemurian, while the
Rotzo Member roughly corresponds to the
Pliensbachian. Each member has a thickness
that can exceed two hundred meters and
show a good lateral continuity nearly all over
the Trento Platform (Fig. 6). The most typical
Fig.7 - Thickening- upward cycle of the Rotzo
Member displaying limestone-marls alternations
at the base and the gradual increase in the
carbonate bed thickness upward.
�
��
Fig.8- On the left, thickening-upward cycle in the Rotzo Fm produced by the emplacement of the
“Lithiotis” bed onto the limestones-marls alternations in the lower portion of the cycles. On the middle,
blow-up of the facies composing the cycle; up, the “Lithiotis” bed showing the crowded packing of the
shells; down, the limestones-marls alternations. On the right, the outcrop aspect of the asymmetric
cycle clearly displaying a thickening up trend of the carbonate beds.
14
and renown facies are the ones present in the
Rotzo Member with abundant plant remains
and extensive banks of oyster-like “Lithiotis”,
probably the most representative and famous
fossil of the Calcari Grigi Formation. Very
recently, the revision of the Stratigraphy,
performed within the Italian Geological Survey
Project (CARG) raised to the group rank the
Calcari Grigi Formation and to the Formation
rank the old members. The new term of
Monte Zugna Formation corresponds to the
former Lower Member; the Loppio Oolite term
replaced the Middle Member and the Rotzo
Member, maintaining the original stratotype, is
now called Rotzo Formation.
sand bodies required by the lagoon definition
itself. The writer tried (Masetti et al, 1998) to
combine these apparently discordant features
proposing the term of ramp-lagoon. Modern
equivalents of this ancient environment, which
are also perfectly comparable in size, are
represented by the coastal lagoons located in
western sector of the Persian Gulf, the best
known modern example of depositional ramp.
More simply,
avoiding the environmental
models of the literature, the subtidal cycles
of the Rotzo Fm could be considered the
sedimentary record of a shallowing upward
evolution of the sea-floor occurred during a
progradational phase that, starting from some
elevated areas, proceeded all around onto the
surrounding and deeper grounds.
2.2 High-frequency cyclicity and depositional
environment of the Rotzo Formation
Masetti et
alii (1998) recognized in the
Rotzo Fm thickening-upward cycles at metric
scale, predominantly subtidal, showing a
characteristic asymmetric profile (Fig. 7 and 8)
due to the different erodibility of the component
lithofacies. Inside these general characteristic,
is it possible to identify a complex typology
of this cycles the most classical expression
of which is illustrated in Fig. 7 and 8 and
consists respectively of the superposition of a
calcarenitic or “Lithiotis” beds to the limestones
- marls alternations.
As in the Late Triassic examples
from
Lombardy, the limestones-marls alternations
represent the base of the cycles and consists
of decimetric beds of grey, peloidal packstone/
wackestone interlayered with grey-greenish
marls; in this lithofacies the carbonate beds
exceed the marl levels showing a clear
thickening-upward trend. Thin (1-10 cm) storm
layers are locally present with disarticulated
valves of bivalves or gastropods pertaining to
the Aptyxiella genus. Frequently referred in the
literature to inter-supratidal environments, this
marly facies has been considered by Masetti et
alii (1998) as deposited onto subtidal sea-floor
that was on average quiet, only occasionally
reached and reworked by storm waves.
The finding in this unit of the above described
subtidal, thickening-upward cycles, seems to
suggest that the depositional environment of the
Rotzo Fm correspond to a depositional ramp,
gently connecting its outer and deeper areas
to the inner and shallower ones. Unfortunately,
the shallow sea of the Rotzo Fm is closed
seaward in both side, to the West and to the
East, by oolitic sand bars located respectively
along the Adige Valley and the Valsugana, (fig
6) thus summarizing the regional gentle slope
inferred in the ramp model with the closure by
2.3 Discussion on the origin of high-frequency
cycles of the Rotzo Fm.
Since the subtidal location of this cycles discards
their possible autocyclic nature, the only viable
Fig. 9- The
Carbonare section.
The
lithostratigraphic column A represents the
interval, 140 m thick, measured in detail.
Column B on the right corresponds to the
black bar aside column A and represents an
enlargement between 24 and 40 m showing
the organization of the 5th order cycles
15
are very rare and are represented by atypical
colonies made by few individuals floating in the
mud. These features suggest that the Rotzo
Fm outcropping in the Carbonare section were
deposited into deep or protected areas of the
lagoon.
More than 90 cycles attributed to the fifth
order have been measured in the section; the
processing of their thickness via BlackmanTuckey algorithm lead to obtain the spectral
analysis displayed in fig 10. Here the numeric
values pertain only to those frequency ratios
exceeding the noise level. This analysis shows
that the basic cycle is bundled in sets with a ratio
of 7.1:1, 4.8:1 and 3.1:1. The frequency ratios
labelled x 7.1 and x 4.8 point to the higher order
hierarchy (4th order) and can be interpreted as
expression of the eccentricity cycles at 100 ka.
Therefore the 5th order cycles represent the
periodicities related to the precession cycle
(around 21 ka). Assuming that, the highest
peak of the spectrum labelled 3,1 :1 should
correspond to a periodicity not present in the
Milankovitch band, but well displayed also in
the spectra performed in the Late Triassic of
the Lombardy. Also in this case, the reliability
of this outcome must be proved through further
analysis.
Fig.10- Spectral analysis of the 5th order cycles
of the Rotzo member at the Carbonare section:
numeric values pertain only to those frequency
ratios exceeding the noise level. For further
explanations , see the text
hypothesis about their origin pertains to an
allocyclic forcing. In order to discover what kind
of allocyclic forcing is recorded in the Rotzo Fm,
in the same way as the methodology before
applied to the Upper Triassic succession of
the Lombardy Basin, the spectral analysis has
been applied to the Carbonare section (Masetti
et alii 1998) (fig. 9). In this section, the total
thickness of the unit here outcropping is 234 m
including two covered segments located at the
base and at the top of the section. The interval
measured in detail is 140 m thick and consists
of a vertical stacking of the cycles illustrated
in fig 7 and consisting in the superposition of
calcarenitic beds to the limestones – marls
couplets at the cycle base. The “Lithiotis” beds
2.4 “Lithiotis” beds
This term is here used in a wide meaning to
indicate depositional bodies characterized by
a shell-supported framework supplied by those
big gregarious bivalves. Since the knowledge
of the geometry and development of the
“lithiotis” beds, frequently located at the cycle
Fig. 11 – . A “Lithiotis” mound in the Rotzo Fm. Folgaria Plateau, Trento.
16
top, could help the understanding the dynamic
of the cycle, it is useful to include here some
information about these sedimentary bodies.
The most widespread geometries of these shells
accumulations are represented by thick (2-4 m)
tabular (at least at the outcrop scale) beds or by
more characteristic lens-shaped accumulations
well known as mounds (Figs.11 and 12).
Mounds may rise from the surrounding floors
for more than 3-4 m. The bivalves settlement
is allowed by the complex interaction between
biological and physical factors; these last
ones are directly related with the depositional
environment and basically linked to the water
quality (temperature, turbidity, oxygenation
level, etc.) and to the bottom firmness. This
last property is strictly linked to the turbulence
degree of the water which is, in turn, a function
of the environment depth: in a wave-dominated
system as the Rotzo Fm (in this unit tidal
evidences are absent or very rare) the shallow
floors are more frequently reworked by waves
and consequently more turbulent and coarser;
inversely, deeper areas are calmer and covered
by muddy deposits The first settlement of the
”Lithiotis” beds within the Rotzo Mb. needed
an hard bottom since the juvenile Cochlearites
shells directly cemented to the substratum; in a
following development phase the right posture
of the individual was granted by mud and
by the high density of the settlement. A nice
example of “Lithiotis” mound outcrops along the
Folgaria-Tonezza road, somewhat eastward to
the Valbona Pass, a mound (Figs. 11and 12)
at the top of an asymmetric cycle whose lower
portion is constituted by the limestone-marls
alternations (A in Fig. 12). On top of these
alternations, the first colonization phase is
recorded by a flat body made up of small and
thin “Lithiotis” shells (B). This first settlement
fades upward in a thick and crowded colony
constituted by the classic large “Lithiotis” shells
representing the main portion of the entire
mound (C). Trying to reconstruct the vertical
and lateral evolution of this mound, also in
term of sequence stratigraphy, the vertical
transition between B and C can be interpreted
as a backstepping phase leading to the retreat
of the colony towards the left of the figure. The
oblique surfaces dipping to the right record
the progradation in the same direction of the
mound; the shell fabric, flat at the top, inclined
and parallel to clinoforms at the flanks of the
mound, suggests that the mound progradation
was allowed by the continuous shells addition
to the mound flank. This shell addition to
the flanks of the mound is interpreted as a
primary living posture of the mollusks and not
a mechanical accumulation. The colony death
is recorded by the storm layer represented by
a “Lithiotis” rudstone (D) eroding and flattening
the top and blanketing the flanks of the mound.
The last phase is represented by the infilling
of the depression adjacent to the mound; the
corresponding deposits (E), lay in onlap on the
flank of the mound
References
Masetti D., Stefani M. & Burchell M. (1989)
- Asymmetric cycles in the Rhaetic facies of
Southern Alps: platform-basin interactions
governed by eustatic and climatic oscillations.
Riv.It.Paleont.Strat., 94, 401-424.
Fig. 12 – Schematic interpretation of the vertical and lateral evolution of the “Lithiotis” mound
illustrated in Fig. 11. For further explanations, see the text.
17
Burchell M.T., Stefani M. & Masetti D. (1990) - Cyclic
sedimentation in the Southern Alpine Rhaetic: the
importance of climate and eustasy in controlling
platform-basin interactions. Sedimentology, v.
37, p.p. 795-815.
Jadoul, F., Masetti, D., Cirilli, S., Berra, F., Claps,
M. & Frisia, S (1994) - Norian-Rhaetian
Stratigraphy and paleogeographic evolution
of the Lombardy Basin (Bergamasc Alps), in:
Carannante G. & Tonielli R. eds. Post-meeting
Fieldtrip Guidebook, 15th IAS Regional Meeting
Ischia, Italy, pp.3-38, Ischia.
Masetti D., Claps M., Giacometti A., Lodi P.
& Pignatti P. (1998) - I Calcari Grigi della
Piattaforma di Trento (Lias Inferiore e Medio,
Prealpi Venete). Atti Tic. Sc. Terra, 40: 139-183
18
Thirty years of Sequence Stratigraphy: Applications, Limits and Prospects - 2 October 2006 - Bari - Italy
FORAMOL (TEMPERATE-TYPE) VS CHLOROZOAN (TROPICAL-TYPE) CARBONATE
PLATFOMS: DEPOSITIONAL DYNAMICS AND ARCHITECTURE OF THE RELATED
DEPOSITIONAL SYSTEMS
Lucia Simone and Gabriele Carannante
Dipartimento di Scienze della Terra, Università degli Studi di Napoli “Federico II”, Largo
San Marcellino 10, 80138 Naples, Italy. e-mail: [email protected]
Based on the study of Meso-Cenozoic
limestones and Recent counterparts from the
Mediterranean Region, the temperate-type
(foramol) carbonate depositional settings
appear to be open systems supporting complex
arrangements of winnowed, partially remobilized
and/or resedimented lithofacies. The winnowing
and remobilization processes act on shelves
whose margins may be more or less steep,
depending on the depositional, erosive and/or
tectonic controls. Related carbonate factories
are characterized by a low in situ preservation
potential of the produced calcite-dominated
bioclastic debris whose early cementation
is very rare. Storm-related cohesionless
gravity flows may easely transport sediments
offshore from marginal areas of the shelf.
Major episodes of resedimentation of bioclastic
debris are periodic and/or intermittent, related
with terminal high stands and/or regressive
phases of the sea level. An active presorting
of the bioerosion-derived skeletal debris results
in early off-shelf swepting and fall-out of the
shelf-derived fines, and in off-shelf transport of
coarse skeletal debris by means of sand flows.
A relatively low aggradation along with a strong
tendency to the progradation characterize the
temperate open depositional settings with a
significant downdeep migration of the main
depocenters. In some cases, complex channel
networks act as sediment pass-way toward
deeper areas. The resulting progradational
wedges are made up of uncemented skeletal
grainstone sheets and/or elongated channelrelated, partially cemented sandy bodies,
intercalated with muddy-silty deposits.
The resulting sedimentary complex differs
from the tropical carbonate systems in terms
of nature and mineralogy of the components,
sedimentary texture, diagenetic potential and
3D geometries.
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Thirty years of Sequence Stratigraphy: Applications, Limits and Prospects - 2 October 2006 - Bari - Italy
SEQUENCE STRATIGRAPHY OF DELTAIC AND SHALLOW LACUSTRINE DEPOSITS,
JUVENTAE CHASMA (MARS)
Gian Gabriele Ori
International Research School of Planetary Sciences, Universita’ d’Annunzio,
Viale Pindaro 62, 40135 Pescara
Sedimentary basins on Mars have been
identified in the past and several of them
are lacustrine in origin. These basins are
associated with sedimentary bodies that are
interpreted as the product of fluvial, deltaic, and
wave dynamics. However, the observations so
far have been based on morphological data
and analysis. The High Resolution Stereo
Camera has remarkable stereo capabilities and
it allows three-dimensional analysis of Martian
outcrops in cliffs and slopes in a way similar to
the study of large terrestrial outcrops or seismic
lines. The aim of this paper is to describe the
facies and strata patterns of two large outcrops
corresponding to Interior Layered Deposits
(ILDs) in Juventae Chasma. In this chasma
there are two major hills of ILDs: the northern
hill deposits are interpreted as deltaic deposits
and the southern deposits are interpreted as
sebkha evaporitic deposits with intervening
aeolian deposits.
Large-scale delta: The large cliffs forming the
slope of the hill show the internal stratification
exhumed by erosion, allowing a detailed
analysis of the stratigraphy and facies. The
internal stratal geometry is dominated by an
overall stratification inclining southwards.
Inclined strata may be observed in both sides
(east and west) of the hill and they comprise
almost the entire body. Unconformities and
sequences occur within this outcrop, but
the general geometry is a thick set of strata
inclined with angles ranging from 15 to 25
degrees (the angles have been estimated as
in the usual terrestrial fieldwork by viewing the
stratification in three dimensions). Due to the
strong erosional processes the top of the hill
has been removed. However, at places, it is
possible to see the inclined beds to become
horizontal at their upper termination. Moreover,
when observable, the base of the inclined strata
becomes flat and horizontal.Therefore, even
if the bulk of the hill consists of the inclined
strata they appear to become horizontal at
their termini. The observed geometry is very
well known in terrestrial deltaic deposits where
a three-fold stratal pattern is produced by the
progradation of deltaic bodies: (i) the horizontal
upper strata are the topset facies representing
fluvial and delta plain deposition that supplied
detritus for the construction of the delta and the
horizontal strata mark the level of water inside
the basin, (ii) the inclined strata are he foreset
package that represents the slope of the delta,
and they connect the shoreline (topset) with
the basin floor, (iii) the horizontal strata in
the lower part are the most distal part of the
delta accumulated on the basin floor and they
represent the bottomset facies. At places the
bottomset strata may be replaced by downlap
geometry.
Sebkha and aeolian facies: The general
stratal pattern of the outcrops of the southern
hill resemble classic transgression – regression
cycle. From the geometry, the high-albedo
strata are the proximal deposits in contrast
to the low-albedo deposits that represent the
distal facies. The proximal (marginal) facies are
probably evaporitic material as suggested by
their albedo and the spectral data. The darker
material probably represents a more clastic
lithology that may consist of clay to coarse
grained silt. The general horizontal stratification
pattern without major discontinuities, the
absence of sedimentary structures linked to
high-energy currents is indicative of low-energy
deposition from suspension. This scenario is
in good agreement with the interpretation of
evaporitic marginal facies passing (northwards)
into basinal clastic facies deposited in a body
of standing low-energy water. The east slope
of the hill shows again the previous facies and
mostly the evaporitic deposits. However, the
outcrop is dominated by a unit consisting of
cross-bedded material. The unit averages a
thickness of about 200 metres but it seems
that at places it can become thicker. However,
the changes in thickness are due to relives of
the top because the bottom of the unit remains
approximately at the same elevation. Internally
the unit show strata inclined in several
directions with apparent angle (it is impossible
to measure the true attitude) of 20–30 degrees.
These cross-strata are organized in sets 20 to
50 metres thick. However, at the base of the unit
a single cross-bedded set attains a thickness in
21
excess of 100 metres. Whereas the base of
the unit is near horizontal the upper boundary
is irregular, but due to the quality of the image
it is possible to do detailed observations only in
particular locations. In these instances, the top
of the unit is gentlely curved and the overlaying
strata drape these smooth irregularities. Largescale cross bedding is produce in several
subacqueous environments but the facies and
geological setting of these ILDs suggest these
deposits have been accumulated by wind
processes as large-scale aeolian dunes. This
situation is common on Earth where sebkha
environments are strictly connected to aeolian
dunes.
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Thirty years of Sequence Stratigraphy: Applications, Limits and Prospects - 2 October 2006 - Bari - Italy
DEPICTING CORRELATIVE CONFORMITIES ON HIGH-RESOLUTION SEISMIC DATA
Francesco Chiocci
Università di Roma “La Sapienza”, Dipartimento di Scienze della Terra,
Piazzale Aldo Moro 5, 00185 Roma. E-mail: [email protected]
Single-channel high-resolution seismics is
the more effective tool to apply sequence
stratigraphic concepts at a nearly an outcrop
scale, as it provides an ordered grid of
profiles to reconstruct subsurface geometries
but in the meanwhile a resolution able to
depict sedimentary meso-structures for
paleoenvironmental reconstruction.
It is therefore possible to use small-scale features
to highlight key horizons, namely condensed
section and correlative unconformities that
bound high-order depositional sequences in
continental slope environment.
This is a critical information as often the
unconformities correlated with continental
slope conformities were eroded by subsequent
sea level falls, due to the constancy of
the bathymetric range into which the Late
Pleistocene sea level fluctuated.
Tectonic, depositional and instability features
may therefore be used, by benefiting of the very
variable sedimentation rate on the continental
slope. Here periods of massive sedimentation
during the long Late Pleistocene sea level
fall and lowstand, alternated with periods of
sediment starvation during the fast sea level
rise and highstand when most of the sediment
was sequestrated on fluvial valleys or into the
continental shelves.
Retrogressive erosion at canyon head,
activation of upper slope hyperpycnal flows,
interaction between large scale tectonic
deformation and sedimentation are among the
features that can be used in this respect.
Examples from the Ionian as well as from
Central and Southern Tyrrhenian Sea will be
used to describe this application of sequence
stratigraphy concepts to constrain seismic
stratigraphic interpretation on continental
margin where erosional unconformities were
not preserved.
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Thirty years of Sequence Stratigraphy: Applications, Limits and Prospects - 2 October 2006 - Bari - Italy
SEDIMENT ROUTING, RELATIVE SEALEVEL FLUCTUATIONS AND THE GROWTH OF
QUATERNARY DEPOSITIONAL SEQUENCES IN THE CENTRAL MEDITERRANEAN
Fabio Trincardi1 Alessandra Asioli2, Andrea Piva1, Domenico Ridente1
1
2
ISMAR (CNR), via Gobetti 101, 40129 Bologna, Italy
IGG (CNR), corso Garibaldi 37, 35137 Padova, Italy
Quaternary continental margins record the
impact of relative sea level changes and abrupt
fluctuations of sediment flux. Relative sea level
changes are a complex function of eustasy,
loading, compaction and regional tectonics
(subsidence, uplift and margin tilt). Detailed
interpretations of the internal geometry and
external morphology of marine deposits allow
reconstruction of the impact of very short-term
supply fluctuations (on time scales of decades
to centuries). Results from EU-funded projects
Eurodelta and Eurostrataform offer increasing
evidence of the pervasive role played by
advection in dispersing sediment along
Mediterranean margins. Four continuousrecovery boreholes acquired by Promess 1
provide time constraints on the growth patterns
of progradational deposits on the Gulf of Lions
and Adriatic margins and allow re-evaluate of
similar deposits in other Mediterranean shelf
and slope settings.
A glimpse to the key characters of the lateHolocene high-stand deposits (HST) in
relation to processes that can be observed
today shows that, away from major deltas,
shore-parallel prograding clinoforms are
tens of meters thick and rest above subtle
regional downlap surfaces. Two main factors
determine the thinning of clinoforms through
the bottomset. Beside the gradual decrease of
sediment received, basin ward, a key control is
the energy impact of bottom currents flowing
along the contour. The excess of energy
prevents deposition or favors episodic resuspension, hampering the basinward growth
of the clinoforms. In this view, bottom currents
induce lateral (advective) rather than basin
ward transport of sediment with the formation
of elongated clinoform bodies characterized by
a shore-parallel strike of the foreset.
The reconstruction of the stratigraphy of four
100-kyr depositional sequences paced by
glacial-interglacial cycles during the last ca
400,000 years in the Adriatic, based on the
results of PROMESS 1 borehole PRAD1-2 (71
m down to the top of MIS 11) documents that
interglacial intervals are “over-represented”,
compared to glacial ones in settings where
intervals of increased accommodation are
accompanied by a strengthening of shoreparallel sediment transport. These new results
are then compared to reconstructions of
fourth- order depositional sequences on other
Mediterranean margins and to “classical” (bidimensional) sequence-stratigraphy models.
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Thirty years of Sequence Stratigraphy: Applications, Limits and Prospects - 2 October 2006 - Bari - Italy
THE SEQUENCE STRATIGRAPHY OF THE QUATERNARY SUCCESSIONS:
IMPLICATIONS ABOUT THE ORIGIN AND FILLING OF INCISED VALLEYS AND THE
MAMMAL FOSSIL RECORD
Salvatore Milli
Università di Roma “La Sapienza”, Dipartimento di Scienze della Terra,
Piazzale Aldo Moro 5, 00185 Roma. E-mail: [email protected]
in this deposits. Our attention has been
devoted to the analysis of the Middle-Upper
Pleistocene to Holocene deposits constituting
a well-differentiated unit named Ponte Galeria
Sequence (PGS). The PGS is a third order
sequence consisting of a variety of depositional
systems ranging from fluvial, fluvio-lacustrine
to coastal barrier-lagoonal and transition-shelf.
These systems are organized to constitute
the lowstand, the transgressive and the
highstand systems tracts. Volcaniclastic
deposits belonging to the Albani and Sabatini
volcanic complexes are interbedded with
these sediments. The PGS is a composite
depositional sequence
consisting of ten
fourth-order depositional sequence (from PG0
to PG9) with an approximate period of 100,000
years, a timing corresponding to high-frequency
sea-level changes. The first five fourth-order
depositional sequences stack to form the LST;
the subsequent sequences from to PG5 to part
of PG9, are ascribed to the TST, whereas the
HST sediments were deposited during the last
6000 concomitantly with the HST sedimentation
The sedimentary cyclicity that characterizes
the Quaternary stratigraphic record represents
an excellent example of the influence of glacioeustatic signal on the sedimentary successions,
during this period. In the Middle-Late Pleistocene
a 100 ka climatic cyclicity, well evidenced by the
oxygen isotopic record appears to dominate the
worldwide paleoclimatic record. This climatic
cyclicity gave rise to sea-level changes of
the same frequency that enabled to gave rise
high-frequency depositional sequences (4thorder) with different thicknesses and internally
characterized by a complete or uncompleted
preservation of the lowstand, transgressive and
highstand systems tracts.
The Middle-Upper Pleistocene to Holocene
deposits cropping out along the Latium coastal
margin near Rome represent a excellent
example of a sedimentary succession where
the close interaction between glacioeustatic
sea-level changes, tectonic uplift and
volcanism determined the conditions to modify
the evolutive tendency of the third and fourth
orders depositional sequences recognized
Fig. 1- Chronostratigraphy and sequence stratigraphy framework of the Roman Pleistocene deposits
and comparison with the faunal units.
27
of the PG9 sequence (Fig 1).
The deposits of these sequences occupied
half-graben basins, formed along the Latium
coastal margin owing to extensional tectonics.
Normal faults, with a dominantly NW-SE trend
and dipping SW, conditioned the depositional
gradient of this area, essentially characterized
by a coastal plain with incised valleys, mainly
oriented NE-SW. A dramatic change in fluvial
drainage occurred starting to the PG5 sequence
in connection with the beginning of the volcanic
activity. Rivers in the northwestern sector of the
area continued to flow towards the sea within
incised valleys generally NE-SW oriented.
Other rivers were forced to flow towards the
SE within fault-controlled incised valley, NWSE oriented, and etched into the margins of
the Paleo-Tiber valley. Both these differently
oriented incised valleys were mainly filled with
fluvial, fluvio-lacustrine and marshy-lagoonal
deposits related to the TST and partially HST of
the PG5, PG6, PG7 and PG8 sequences. Most
of the mammal fossil remains of the Latium
area were discovered within these deposits.
Their preservation was strictly controlled by the
geomorphological evolution of these incised
valleys that changed their morphological profile
during the lowstand and transgressive phases.
Incision and widening of the valleys during the
relative sea level fall and during the relative
sea level rise respectively, took place as
expression of the superimposition of allogenic
and autogenic processes. These processes
produced local mixing of mammal fossil remains
often characterized by the coexistence of more
ancient exhumed bones with others suggesting
a their provenance by organisms mostly coeval
with deposits containing them. In this light it is
evident that the biochronological value of each
faunal assemblages must be considered taking
into account not only the single mammalian
assemblage but also the facies and the physical
stratigraphic framework of the deposits in which
vertebrate fossil remains occurred. Sequence
stratigraphy can help to unravel this problem
because it allow to define regional and local
chronostratigraphic framework which sets some
physical and temporal limits to the occurrence
of faunal complexes.
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Thirty years of Sequence Stratigraphy: Applications, Limits and Prospects - 2 October 2006 - Bari - Italy
APPLICATION OF SEQUENCE STRATIGRAPHIC CONCEPTS TO A HIGHLY
SUBSIDING BASIN: THE EXAMPLE OF THE PO PLAIN
Alessandro Amorosi
Dipartimento di Scienze della Terra e Geologico-Ambientali, Università di Bologna,
Via Zamboni 67, 40127, Bologna
Developing a realistic model of sequence
stratigraphy from the subsurface of modern
alluvial and coastal plains is an important first
step toward a successful three-dimensional
representation of aquifers and aquifer systems.
The very good geochronological framework
available for the Quaternary, combined with a
generally scarce degree of tectonic deformation
of middle-late Quaternary deposits, and a very
well known eustatic and climatic history for this
interval of time, allow in most cases to define
reliable sediment-body (reservoir) geometries,
and to portray high-resolution stratigraphic
architecture, with climate and sea-level
changes as forcing mechanisms.
The proposed global sea-level chart (Haq et al.,
1987; 1988), based upon the theory that thirdorder relative sea-level variations are mostly
eustatic in origin, has been extensively used in
the past twenty years to sequence stratigraphic
purposes. Global synchroneity, however, can be
better documented on a detailed stratigraphic
basis when applied to fourth-order and fifthorder cycles of late Quaternary age (Blum &
Törnqvist, 2000).
The Po Plain is the surface expression of a
peri-sutural basin, bounded to the south by the
Apennines and to the north by the Alps, with
its southern prolongation into the Adriatic Sea.
The region largely corresponds to a foredeep
basin, developed during Neogene times and
subject to active tectonic deformation. Because
of the active structural framework, lower to
middle Quaternary deposits of the Po Basin
show comparatively reduced thickness (a few
metres) in ramp anticline zones, whereas they
can exceed several hundreds of metres in
the depocentres. By contrast, late Quaternary
deposits exhibit very low evidence of tectonic
activity, allowing a prompt application of the
genetic facies models.
High-resolution
sedimentological
and
stratigraphic analysis of middle-late Quaternary
fluvial to shallow-marine successions of Po River
Plain (Northern Italy) was performed through
analysis of hundreds of continuous cores up
to 200 m long drilled by the Geological Survey
of Regione Emilia-Romagna. Stratigraphic
architecture reveals distinctive cyclic changes
in lithofacies and channel stacking patterns
that can be attributed to the past 400 ka, with
a hierarchy of cycles falling in the Milankovitch
(Amorosi et al., 2004) and sub-Milankovitch
(Amorosi et al., 2005) band.
Regional mapping in late Quaternary deposits
of the Po Basin relies upon two prominent
stratigraphic markers, corresponding to wedgeshaped coastal sand bodies, which are recorded
between 0-30 m and 100-125 m core depths
beneath the present Adriatic coastal plain.
These sedimentary bodies were deposited
during the two major transgressive pulsations
and subsequent sea-level highstands of the
last 150 ky (OIS 1 and 5e, respectively).
Application of sequence-stratigraphic concepts
to the analysis of cores from the subsurface of
the Po Plain shows that transgressive surfaces
represent the most readily identifiable bounding
surfaces between cycles. These surfaces are
generally marked by abrupt facies changes
across a significant part of the basin. Lateral
tracing of transgressive surfaces may become
increasingly difficult at landward locations, in
the proximal alluvial plain. At this site, however,
the transgressive surface is commonly
identified within relatively homogeneous
alluvial clay deposits, at the boundary of thin
organic-rich (peat) horizons with overlying stiff
floodplain clays. As a whole, the transgressive
surfaces constitute basinwide stratigraphic
markers that show easier recognition, greater
extent and higher correlation potential than
sequence boundaries (Posamentier & Vail,
1988; Posamentier et al., 1988) or maximum
flooding surfaces (Galloway, 1989).
Identification
of
sequence
boundaries
from the Po Plain core data is neither easy
nor unambiguous. Particularly, inability to
recognize large-scale geometries generally
prevents interpretation of erosional surfaces,
lag deposits or sharp-based channel sands
as sequence boundaries. Similarly, the
maximum flooding surface has no obvious
physical expression. It generally occurs within
homogeneous shallow-marine sediments, and
can be detected uniquely on the basis of subtle
29
micropalaeontological variations. These allow
the distinction between retrograding offshore
clays and prograding prodelta deposits
(Amorosi & Colalongo, 2005).
Stacked transgressive-regressive sequences
(see T-R sequences of Embry, 1993; 1995) can
be correlated on a basin scale, and form the
basic motif of middle-late Quaternary alluvial
and coastal deposits of the Po Basin (Amorosi
et al., 1999b, 2004; Amorosi & Colalongo,
2005). In terms of sequence stratigraphy, these
T-R sequences, which are 50-100 m thick
and span intervals of time of about 100 ka,
correspond to fourth-order cycles.
At relatively seaward locations, the lower parts
of T-R sequences form thin transgressive
systems tracts (TST), showing coastal-plain
aggradation and rapid shoreline transgression,
which have been interpreted to represent the
landward migration of barrier-lagoon-estuary
systems. The TSTs are overlain by thicker
shallowing-upward successions (highstand
systems tracts), reflecting progradation of
deltas and adjacent strandplains (Amorosi et
al., 1999a; 2003). At landward locations, within
non-marine strata, the bounding surfaces of
T-R sequences are marked by abrupt facies
changes from amalgamated fluvial-channel
gravel and sand, formed mostly at lowstand
conditions, to mud-dominated floodplain
deposits, with isolated channel bodies and
organic horizons (transgressive alluvial
deposits or TST). This interval grades upward
into thick alluvial plain deposits, showing
increased channel clustering and sheet-like
geometries (regressive alluvial deposits,
including HST, FST, and LST). The sharp lower
boundaries of T-R sequences identified within
the alluvial sections can be traced physically
into the transgressive surfaces recognized at
distal locations, allowing the establishment
of the physical linkage between alluvial and
marine deposits (Amorosi & Colalongo, 2005).
The repetitive alternation of coastal and
alluvial deposits is paralleled by a distinctive
pollen signature. Particularly, stratigraphic
correlation with the marine oxygen-isotope
record on the basis of pollen data, documents
strict relationships between T-R sequences
and interglacial/glacial cycles, showing that
transgressive surfaces correlate invariably
with the onset of forested conditions during
interglacials, whereas return to alluvial
sedimentation correlates with abrupt change
to open vegetation conditions during glacials
(Amorosi et al., 2004; Amorosi & Colalongo,
2005).
This study shows that when dealing with
the sequence-stratigraphic interpretation of
depositional sequences formed during sealevel fluctuations with frequencies of 100 ka,
placing the sequence boundary either at the
onset of relative sea-level fall (Posamentier
et al., 1992; Kolla et al., 1995; Morton & Suter,
1996) or at its end (Hunt & Tucker, 1992; 1995),
in coincidence of the maximum regressive
surface of Helland-Hansen & Martinsen (1996)
becomes problematic, because of the strong
asymmetry in the curves of sea-level variation,
characterized by comparatively long periods
(up to 90 ka) of sea-level fall, punctuated by
higher-frequency sea-level cycles.
A general assumption of sequence-stratigraphic
models is that initiation of fluvial incision by
relative sea-level fall results in formation of
the sequence-bounding unconformity, and
that as relative sea-level continues to fall,
the coastal plain is incised and sediment bypasses the highstand fluvial- and coastal plains
(Posamentier & Allen, 1999). As a consequence,
when fluvial incision occurs, in alluvial plain and
coastal plain areas outside of incised valleys an
amalgamated unconformity develops, and the
two types of sequence boundary merge into a
single surface.
Data from the last glacial/interglacial (post 125ka BP) cycle of the Po Basin differ markedly from
the original EXXON model, documenting that
significant deposition may occur during the long
periods of base-level fall (see remarks by Blum
& Törnqvist, 2000). In the structurally active Po
Basin, the sequence stratigraphic signature
appears to be strongly influenced by the high
subsidence rates. Specifically, tectonically
induced accommodation allowed accumulation
of an extremely thick (60 m) succession of
alluvial and coastal-plain deposits during the
prolonged sea-level fall between 125 and 20
ka BP (i.e. FST). As recently shown by Amorosi
et al. (2004), the FST in the Po Basin consists
of vertically stacked transgressive/highstand
deposits (5th-order depositional sequences),
separated by closely-spaced unconformities
that mark the progressive basinward shifts of
facies during longer-period, 4th-order sea-level
fall.
Recognition of sequence boundaries is
increasingly difficult landwards, within nonmarine successions consisting entirely of
alluvial strata. In these instances, amalgamated
fluvial-channel bodies are invariably located
below the transgressive surfaces, suggesting
deposition during phases of increased
sediment supply and slowed accommodation,
immediately preceding the major transgressive
phases, and leading to increased channel
30
clustering (Leeder, 1978; Holbrook, 1996).
Although most of these amalgamated fluvialchannel bodies can be broadly assigned to
the LST, whether or not they are LST or partly
late FST deposits is equivocal. This is probably
the reason why some authors (see Legarreta
& Uliana, 1998) have suggested grouping
these highly-interconnected fluvial sheets into
a unique systems tract (forestepping systems
tract).
In conclusion, the general assumption that
the sequence boundaries coincide with lower
boundaries of amalgamated fluvial-channel
bodies (Shanley & McCabe, 1991, 1994;
Posamentier & Allen, 1993, 1999; Van Wagoner,
1995) is invalid for the Po Basin, due to high
preservation of falling-stage deposits, and
should not be applied whenever subsidence (or
high-frequency sea-level cycles) may create
accommodation, exceeding the effects of sealevel fall.
Finally, correlation of high-frequency (1,000
years) parasequences, 3 to 5 m thick, based
upon closely-spaced cores in the Holocene
deposits of the Po Plain allows to document
a significant diachroneity of the MFS
(Amorosi et al. 2005). The stacking pattern
of parasequences within the TST exhibits a
consistent pattern throughout the study area
and appears to have been controlled mostly by
acceleration and deceleration of sea-level rise.
By contrast, parasequence development in the
HST seems to reflect fluctuations in sediment
supply rather than changes in relative sea level.
During this period, local (autocyclic) processes,
such as distributary channel avulsion and
delta lobe abandonment, prevailed on external
(allocyclic) controlling factors. The maximum
flooding surface can not be assumed to
be synchronous, its timing being strongly
dependent upon local variations in sediment
influx and subsidence.
Quaternary deposits of the south-eastern Po
Plain (Northern Italy). Quaternary Research, 52,
1-13.
AMOROSI A., CENTINEO M.C., COLALONGO M.L., PASINI
G., SARTI G. & VAIANI S.C. (2003) - Facies
architecture and latest Pleistocene-Holocene
depositional history of the Po Delta (Comacchio
area), Italy. Journal of Geology, 111, 39-56.
AMOROSI A., COLALONGO M.L., FIORINI F., FUSCO
F., PASINI G., VAIANI S.C. & SARTI G. (2004) Palaeogeographic and palaeo≠climatic evolution
of the Po Plain from 150-ky core records. Global
and Planetary Change, 40, 55-78.
AMOROSI A., CENTINEO M.C., COLALONGO M.L. & FIORINI
F. (2005) - Millennial-scale depositional cycles
from the Holocene of the Po Plain, Italy. Marine
Geology, 222-223, 7-18.
BLUM M.D. & TÖRNQVIST T.E. (2000) - Fluvial response
to climate and sea-level change: a review and
look forward. Sedimentology, 47 (Suppl. 1), 248.
EMBRY, A.F. (1993) - Transgressive-regressive (T-R)
sequence analysis of the Jurassic succession of
the Sverdrup Basin, Canadian Arctic Archipelago.
Can. J. Earth. Sci., 30, 301-320.
EMBRY, A.F. (1995) - Sequence boundaries and
sequence hierarchies: problems and proposals.
In: Steel R.J., Felt V.L., Johannessen E.P. &
Mathieu C. Eds., Sequence Stratigraphy on
the Northwest European Margin Spec. Publ.
Norwegian Petrol. Soc., 5, 1-11.
GALLOWAY W.E. (1989) - Genetic stratigraphic
sequences in basin analysis I: architecture and
genesis of flooding-surface bounded depositional
units. Am. Ass. Petrol. Geol. Bull., 73, 125-142.
HAQ B.U., HARDENBOL J. & VAIL P.R. (1987) Chronology of fluctuating sea levels since the
Triassic. Science, 235, 1156-1167.
HAQ B.U., HARDENBOL J. & VAIL P.R. (1988) - Mesozoic
and Cenozoic chronostratigraphy and cycles of
sea-level change. In: Wilgus C.K. Hastings B.S.
Kendall C.G.St.C., Posamentier H.W., Ross C.A.
& Van Wagoner J.C. Eds., Sea Level Changes:
An Integrated Approach, Spec. Publ. Soc. Econ.
Paleont. Miner., 42, 71-108.
HELLAND-HANSEN W. & GJELBERG J.G. (1994) Conceptual basis and variability in sequence
stratigraphy: a different perspective. Sedimentary
Geology, 92, 31-52.
HELLAND-HANSEN W. & MARTINSEN O.J. (1996) Shoreline trajectories and sequences: description
of variable depositional-dip scenarios. Journal of
Sedimentary Research, 66, 670-688.
HOLBROOK J.M. (1996) - Complex fluvial response to
low gradients at maximum regression: a genetic
link between smooth sequence-boundary
morphology and architecture of overlying sheet
sandstone. Journal of Sedimentary Research,
66, 713-722.
HUNT, D. & TUCKER, M.E. (1992) - Stranded
parasequences and the forced regressive wedge
systems tract: deposition during base-level fall.
Sedimentary Geology, 81, 1-9.
References
AMOROSI A. & COLALONGO M.L (2005) - The linkage
between alluvial and coeval nearshore marine
successions: evidence from the Late Quaternary
record of the Po River Plain, Italy. In: Blum
M.D., Marriott S.B. & Leclair S.F. Eds., Fluvial
Sedimentology VII. Spec. Publs int. Ass.
Sediment. 35, 257-275.
AMOROSI, A., COLALONGO, M.L., PASINI, G. & PRETI,
D. (1999a) - Sedimentary response to Late
Quaternary sea-level changes in the Romagna
coastal plain (northern Italy). Sedimentology, 46,
99-121.
AMOROSI A., COLALONGO M.L., FUSCO F., PASINI G. &
FIORINI F. (1999b) - Glacio-eustatic control of
continental-shallow marine cyclicity from Late
31
HUNT, D. & TUCKER, M.E. (1995) - Stranded
parasequences and the forced regressive wedge
systems tract: deposition during base-level fall Reply. Sedimentary Geology, 95, 147-160.
KOLLA V., POSAMENTIER H.W. & EICHENSEER H. (1995)
- Stranded parasequences and the forced
regressive wedge systems tract: deposition
during base-level fall - Discussion. Sedimentary
Geology, 95, 139-145.
LEEDER M.R. (1978) - A quantitative stratigraphic
model for alluvium, with special reference to
channel deposit density and interconnectedness.
In: Miall A.D. Ed., Fluvial Sedimentology, Can.
Soc. Petrol. Geol. Mem., 5, 587-596.
LEGARRETA L. & ULIANA M.A. (1998) - Anatomy of
hinterland depositional sequences: Upper
Cretaceous fluvial strata, Neuquen Basin, WestCentral Argentina. In: Shanley K.W. & McCabe
P.J. Eds., Relative Role of Eustasy, Climate, and
Tectonism in Continental Rocks, Spec. Publ.
Soc. Econ. Paleont. Miner., 59, 83-92.
MORTON R.A. & SUTER J.R. (1996) - Sequence
stratigraphy and composition of Late Quaternary
shelf-margin deltas, Northern Gulf of Mexico.
Am. Ass. Petr. Geol. Bull., 80, 505-530.
POSAMENTIER H.W. & VAIL P.R. (1988) - Eustatic
controls on clastic deposition II - Sequence and
systems tract models. In: Wilgus C.K. Hastings
B.S. Kendall C.G.St.C., Posamentier H.W.,
Ross C.A. & Van Wagoner J.C. Eds., Sea Level
Changes: An Integrated Approach, Spec. Publ.
Soc. Econ. Paleont. Miner., 42, 125-154.
POSAMENTIER H.W. & ALLEN G.P. (1993) - Siliciclastic
sequence stratigraphic patterns in foreland
ramp-type basins. Geology, 21, 455-458.
POSAMENTIER H.W. & ALLEN G.P. (EDS.) (1999)
Siliciclastic Sequence Stratigraphy – Concepts
and Applications. SEPM
Concepts in
Sedimentology and Paleontology, 7.
POSAMENTIER H.W., JERVEY M.T. & VAIL P.R. (1988)
- Eustatic controls on clastic deposition I:
Conceptual framework. In: Wilgus C.K. Hastings
B.S. Kendall C.G.St.C., Posamentier H.W.,
Ross C.A. & Van Wagoner J.C. Eds., Sea Level
Changes: An Integrated Approach, Spec. Publ.
Soc. Econ. Paleont. Miner., 42, 109-124.
POSAMENTIER H.W., ALLEN G.P., JAMES D.P. & TESSON
M. (1992) - Forced regressions in a sequence
stratigraphic framework: concepts, examples
and sequence stratigraphic significance. Am.
Ass. Petrol. Geol. Bull., 76, 1687-1709.
SHANLEY K.W. & MCCABE P.J. (1991) - Predicting facies
architecture through sequence stratigraphy – an
example from the Kaiparowits Plateau, Utah.
Geology, 19, 742-745.
SHANLEY K.W. & MCCABE P.J. (1994) - Perspectives
on the sequence stratigraphy of continental
strata. Am. Ass. Petrol. Geol. Bull., 78, 544-568.
VAN WAGONER J.C. (1995) - Sequence stratigraphy
and marine to non-marine facies architecture
of foreland basin strata, Book Cliffs, Utah,
U.S.A. In: Van Wagoner J.C. & Bertram G.T.
Eds., Sequence Stratigraphy of Foreland Basin
Deposits, AAPG Memoir, 64, 137-223.
32
Thirty years of Sequence Stratigraphy: Applications, Limits and Prospects - 2 October 2006 - Bari - Italy
AQUIFER CHARACTERIZATION AND HYDROSTRATIGRAPHY OF ALLUVIAL
SEDIMENTS: TAKING ADVANTAGE OF SEQUENCE STRATIGRAPHY METHODS
Riccardo Bersezio1, 2
1
Dipartimento Scienze della Terra – Università di Milano, via Mangiagalli 34, 20133 IMilano
2
CNR – IDPA Milano, via Mangiagalli 34, 20133 I-Milano
evolution within the basin fill. Therefore, the
HSU are defined by their internal lithology
and petrophysical properties but also by their
boundaries, that have a chronostratigraphic
significance, and are associated to their genesis
and controlling factors at the consistent scale. In
this way the results of the forecasting exercise
are greatly improved even in delicate situations,
like in the areas where salinity thresholds are
expected in relation with the position of the
marine base level (both the present-day and
that related to previous sedimentary cycles).
The problem of aquifer sedimentology and
hydrostratigraphy of porous alluvial sediments
is “how to obtain accurate characterizations
of aquifers at different scales”. Basically
this means forecasting: i) the distribution of
porosity and permeability, ii) the recharge, iii)
the paths of groundwater flow including also
velocity and time of water residence in the
reservoirs and iv) the behaviour of aquifers
with respect to natural and anthropogenic
pollutants. Alluvial and paralic aquifers are
heterogeneous and anisotropic concerning
both their sedimentary properties and their
hydraulic behaviour. However, since the
pioneering work of Theis (1935), the physicalmathematical approach to this complexity
consisted in the replacement of the real aquifer
with an equivalent homogeneous medium
for which the Darcy’s law was easily solved,
disregarding the difficult task of reconstructing
aquifer architecture (see Anderson, 1997 for
an historical perspective). This is one reason
for the delay on the applications of modern
stratigraphic,
geophysical,
geostatistical
and numerical methods to hydrogeology,
together with the long-lasting low economical
investments on exploitation of groundwater
resources (review in Huggenberger & Aigner,
1999). After many revolutions, the current
approach to hydrostratigraphy takes advantage
of the integration of multiple disciplines,
including sequence stratigraphy, and focuses
on the description and quantification of aquifer
heterogeneity, following the hierarchic frame of
sedimentary units and cycles. Some relevant
achievements and open problems can be
succinctly outlined as follows.
2) Porosity and permeability are scaledependent. In a (sequence)-stratigraphic
framework the physical scale of the lithosomes
is dependent also on time and therefore on
the rank of the depositional units. This is
reasonable at the sedimentological scale of
(hydro)-facies and architectural elements
and could hold also at the stratigraphic scale
of 5th to 3rd order cycles. However, in the
subsurface of the alluvial basins it is still difficult
to recognise the different-scale sequences
and the sequence stratigraphic surfaces far
away from the regional base-level. In this field
much work must be done to relate correctly the
stratigraphic hierarchy, the physical scale of
heterogeneity, the distribution of porosity and
permeability and the behaviour of groundwater
flow.
3) Dynamic approach. Building and recharge
of aquifers are time-dependent processes.
A dynamic stratigraphic approach (Heinz &
Aigner, 2003) is necessary to be able to relate
the scale of these two processes to the basin
evolution, with the consequent improvements
on the previsions of the distribution of
aquitards and aquicludes. Building and erosion
of aquifers are contemporary processes
during the development of terraced valleys
(FSST or lowering of a local base level). The
subsequent recovery of equilibrium of the
alluvial depositional systems, that is thought to
give origin to aquitards and aquicludes, is much
slower. It is reasonable that complex aquifer
systems, built by 5th to 6th order HSU, are
1) Heterogeneity of alluvial aquifers consists
of nested different-rank elements, from the
lowest rank of the grain-pore assemblage to
facies and architectural elements, then to the
highest ranks of depositional sequences and
2nd order regional cycles. The establishment
of a hierarchy of hydrostratigraphic-sequential
units (HSU) allows to link the physical scale
of the reservoirs to the time-scale of their
33
sealed by aquitards that are formed during the
time span of a higher order cycle. In this way
an HSU with the rank of the aquifer complex
could be a highly asymmetric unit, formed by
several aquifer systems, without corresponding
aquitards, sealed by a composite aquiclude
that results from addition of different aquitards.
Such asymmetric “hidrostratigraphic sequential
cycles” include therefore several repetitive
entrenchment - stability stages followed by a
recovery stage. At this scale, base level and
hydrologic-climatic geomorphologic cycles
(rhexistasy/biostasy) should represent the
forcing factors.
reconstructions, like reflection seismic does in
the study of hydrocarbon reservoirs. Calibration
with well/borehole data and exposed analogue
cases permits to refine the accuracy of the
reconstructions, reducing the gap between
the vertical and horizontal resolution of the
different tools. Multi-scale models, that portray
the nested heterogeneity, can be computed
by geostatistical simulations; then uncertainty
can be quantified and compared with low-cost
and friendly exploration outcomes like the
maps of apparent resistivity that are obtained
from ERGI grids. The hierarchic arrangement
of the hydrostratigraphic models favours the
computation of different-scale flow-models
and the upscaling of the local properties
that are obtained from samples or well tests,
like hydraulic conductivity. At last GPR and
geoelectrical borehole methods can be used
also to monitor the water table dynamics
in order to validate the previsions that are
obtained from numerical modelling of flow
and eventually to suggest refinements of the
architectural model.
For shorter time spans, at the low rank of
the aquifer system (a point bar-channel
depositional element for instance), building,
erosion and recharge of groundwater may
have a comparable time-duration. This fact is
relevant for the stability of river banks and for
triggering of development of meanders, and
bears some different consequences: i) the
rate of this process might influence the fluvial
style contributing to control shape, position and
connectivity of sand lenses; ii) if the accretion
rate is high, these bodies host a water nappe
that might be independent from river recharge.
References
ANDERSON M.P. (1997) - Characterization of
geological heterogeneity. In: Dagan G. &
Neuman S.P. (Eds.), “Subsurface flow and
transport: a stochastic approach”, Cambridge
University Press, Cambridge, 23 - 43.
4) Integration of methods and techniques.
The geological (l.s.), geophysical, stochastic
and numerical approaches to aquifer
characterization and modelling, that have
been developed separately for long time,
are more and more frequently integrated in a
multi-disciplinary methodology. Many mature
geophysical techniques (GPR, VES, ERGI,
HRSS) can be complementary used to assist
correlation of stratigraphic surfaces and
parasequences. The geophysical evidence
of these sequence stratigraphic elements is
becoming well-known also in the alluvial-paralic
successions, at shallow depths and within
waterlogged sediments. Geophysical imaging
of the subsurface can help to build 3-D aquifer
HEINZ J. & AIGNER T. (2003) – Hierarchical dynamic
stratigraphy in various quaternary gravel
deposits, Rhine glacier area (SW Germany):
implications for hydrostratigraphy. Int. J. Earth
Sci., 92: 923 – 938.
HUGGENBERGER, P., & AIGNER, T. (1999) - Introduction
to the special issue on Aquifer Sedimentology:
problems, perspectives and modern approaches.
Sedimentary Geology, 129, 179 - 186.
THEIS C.V. (1935) – The relations between the
lowering of the piezometric surface and the
rate and duration of discharge of a well using
groundwater storage. Trans. Amer. Geophys.
Union, 2, 519 – 524.
34
Thirty years of Sequence Stratigraphy: Applications, Limits and Prospects - 2 October 2006 - Bari - Italy
SEQUENCE STRATIGRAPHY IN VOLCANIC SETTINGS:
EXAMPLES FROM THE CAMPANIA MARGIN
Alfonsa Milia
Istituto per l’Ambiente Marino Costiero, CNR, Calata Porta di Massa, Porto di Napoli,
80133 Napoli, Italy. e-mail: [email protected]
Sequence stratigraphy analysis coupled with
subsidence and tectono-stratigraphic analysis
can be applied to understand the stratigraphic
signatures of each variable within the
stratigraphic record and quantify them in terms
of time and space. Stratigraphic signatures
result from the interaction of tectonic, eustatic,
sedimentary and climatic processes combined
to cause relative changes of sea level which
control the accommodation space. Tectonism
(uplift, faulting, folding), volcanism and climate
control the amount and types of sediments
deposited. The resulting sediment supply
determines how much of the accommodation
space is filled.
In non volcanic siliciclastic terrains sediment
supply is limited by rates of weathering and
erosion in the source area, whereas volcanism
can provide not only a unique and locally
abundant source of sediment to adjacent
basins but virtually instantaneous volumes of
sediment several orders of magnitude greater.
Due to the episodic and catastrophic nature of
sediment supply volcanic terrains are the most
complex surface environments on Earth. The
volumetric importance of sedimentary deposits
around volcanoes has been recognized at least
since the development of plate tectonics, when
volcanic regions were studied to determine their
tectonic setting. The stratigraphic successions
associated with active volcanoes can be
considered to consist of two elements: i) syneruptive sequences - a direct consequence of a
volcanic eruption and immediate post eruptive
reworking; and ii) inter-eruptive sequences
which record deposition when normal
sediment delivery processes are dominant.
In addition volcanic regions are characterized
by unconformities due to sin-genetic erosional
processes, the presence of caldera or crater
depressions, relief inversion, updoming related
to shallow magma intrusion, tectonic and
volcano-tectonic deformations. The occurrence
of unconformities, localized volcanic units and
abrupt lateral changes of sin-eruptive and intereruptive clastic facies in volcanic environments
give rise to complex stratal architectures
and consequently the reconstruction of the
stratigraphic succession is a difficult task.
Basin analysis using the sequence stratigraphic
approach applied in a complex volcanic area is
important for establishing:
•
the stratigraphic succession of porous
and non porous strata that exert a fundamental
controls in the hydrodynamic fluid circulation
from magma chamber, determining the type of
volcanic eruption;
•
the variations in the accommodation
space to evaluate the volcano tectonic
subsidence;
•
the complex interplay between volcanic
and sedimentary deposits in space and time.
•
the meaning of unconformities in a
volcanic area
Naples Bay is an eastern Tyrrhenian extensional
basin characterized by intense volcanism
during the Upper Pleistocene and bounded by
the active volcanoes of Vesuvius and Campi
Flegrei. Vesuvius has been one of the most
active volcanoes in the world. More than 80
eruptions were listed in a recent directory of
volcanic activity. The first historical eruption
was the major plinian explosion of AD 79, which
buried the major Roman cities of Herculaneum
and Pompei. The last eruption occurred in the
1944. Campi Flegrei corresponds to a densely
populated active volcanic region characterized
by ignimbrite eruptions and monogenic
volcanoes; the last Campi Flegrei eruption
occurred in A.D. 1538 and led to the formation
of the 130-m-high cone of Monte Nuovo. Campi
Flegrei also displays outstanding examples of
ground deformations which were discovered
in the nineteenth century around the Roman
ruins of Serapis in Pozzuoli. This region was
subjected to significant ground uplift (320 cm
of cumulative uplift between 1970 and 1984)
and earthquakes in the periods 1970-1972
and 1982-1984. Because of the high level of
urbanization and the presence of Vesuvius and
Campi Flegrei the Neapolitan area is one of the
highest volcanic risk in the world. We maintain
that a detailed stratigraphic analysis plays a
fundamental role in the reconstruction of the
35
geologic history and hazard evaluation of this
volcanic region.
Basin analysis and the extent of the volcanic
units in Naples Bay was ascertained from the
interpretation of approximately 4000 km of high
resolution seismic reflection data collected
from the Istituto di Oceanologia (Parthenope
University,
Naples).
The
stratigraphic
framework was reconstructed using a sequence
stratigraphic approach. A seismic section is a
record of the chronostratigraphic depositional
and structural patterns. Because primary seismic
reflections are generated by physical surfaces
within rocks (mainly stratal surfaces and
unconformities with velocity-density contrast)
they allow the direct application of geologic
concepts based on physical stratigraphy . In
particular, volcanic and sedimentary units were
delineated on the basis of stratal termination
and internal and external seismic configuration.
Indeed, sedimentary deposits on the Naples
Bay continental margin was subdivided on the
basis of their internal geometry and stacking
pattern and referred to distinct phases of sea
level fluctuations according to the sequence
stratigraphic interpretation.
The volcanic units were fitted in the chronostratigraphic framework of the Naples Bay
succession and physically correlated with
dated volcanic units cropping out on the coast
and drilled onshore. On the basis of external
and internal seismic facies numerous volcanic
units made up of monogenetic volcanoes and
thick ignimbrite wedges were recognized in
Naples Bay. The monogenetic volcanoes
offshore Campi Flegrei are inter layered with
epiclastic units that are erosional products of
the adjacent volcanic areas and deposited as
systems tracts. The recognition of criptodomes
and debris avalanches offshore Vesuvius
permitted to discover lateral collapses in the
history of this volcano. The geohistory analysis
of three selected sites of Naples Bay permitted
to calculate curves of accommodation space
filled with volcanics and sediments, and
volcano-tectonic subsidence.
36
Thirty years of Sequence Stratigraphy: Applications, Limits and Prospects - 2 October 2006 - Bari - Italy
THE CALCARENITE DI GRAVINA FORMATION IN MATERA:
A GOOD TRAINING FOR SEQUENCE STRATIGRAPHY
Marcello Tropeano
Dipartimento di Geologia e Geofisica, Università di Bari.
Campus Universitario, Via Orabona 4, 70125 BARI (Italy)
Panoramic views, lateral continuity of both
geometries and facies, and good accessibility
of many outcrops allow to propose the
Calcarenite di Gravina Formation in Matera as
a good training for high-frequency sequence
stratigraphy. In particular close up views of
geometries and surfaces allow to “touch”
rocks and to observe virtual seismic facies of
high-resolution seismic lines; this lets either to
discuss or refine some sequence stratigraphy
dogmas. Moreover, stacking patterns observed
in these natural sections show geometry and/
or dimension similar to those of high-resolution
seismic lines referred to Plio-Quaternary bodies
and obtained from present-day shelves.
here the Calcarenite di Gravina Formation is
mainly lithoclastic, with components derived
from erosion of Cretaceous limestone, and
is composed of accretional units bounded by
erosion surfaces. Accretional units are stacked
in a backstepping configuration, lapping onto
the underlying Cretaceous rocks (Pomar &
Tropeano, 2001).
Thanks to a middle and late Quaternary uplift
(Ciaranfi et al., 1983; Doglioni et al., 1994), the
Matera paleoisland is today exposed and cut
by a complex hydrographic network (Beneduce
et al., 2004).
Depositional model
The accretional units of the Calcarenite
di Gravina Formation in Matera are prism
shaped, elongated in strike section and
parallel to the paleocoast line. They provide
continuous exposure of coarse-grained, graveldominated coastal systems and are composed
of several lithofacies which are conglomeratic
at the proximal end (foreshore) and become
progressively sandier basinward (offshore).
Excellent outcrops in the gorges permit
detailed observations of the internal-facies
architecture of these clastic basin-margin
depositional systems in both dip and strike
sections. Lithofacies are basically dominated
by limestone gravel (from pebbles to granules
sized); carbonate sand, either lithoclastic
or bioclastic, is only significant in offshore
Regional setting
The late Pliocene-lower Pleistocene Calcarenite
di Gravina Formation extensively crops out
in the Murge area (Apulian Foreland, southeastern Italy), where unconformably overlies
faulted Cretaceous rocks of a wide Mesozoic
carbonate platform (the Apulian Platform)
(Iannone & Pieri, 1979). The Calcarenite
di Gravina Formation formed during the
submersion of the foreland (a subsiding karstic
region); subsidence and transgression onto
the Apulian Foreland were induced by the
eastward migration of the south-Apennines
orogenic system (Tropeano et al., 2002).
Before the transgression, the region was
characterized by a horst and graben system,
but the same system governed distribution of
lands and seas during the Plio-Pleistocene
relative sea-level rise; so, the wide exposed
Apulian foreland progressively became a
large drowning archipelago with shallowmarine settings exclusively characterized by
carbonate sedimentation, both autochthonous
(bioclastic) and terrigenous (extraclastic) in
origin (Tropeano & Sabato, 2000).
The Matera Horst was a southwestern small
island of the Murge archipelago during
late Pliocene-early Pleistocene times (fig
1) that finally became drowned during the
regional subsidence-driven transgression. A
punctuated transgression is well recorded on
the southern flank of the Matera paleoisland;
fig. 1 - Paleogeography of Murge area. Note
position of Matera paleoisland.
37
fig 2 - Depositional system and facies, according to Pomar & Tropeano (2001)
settings, and no significant carbonate mud or
clay exists in these facies. Environments range
from beachface to offshore and developed in
a wave-abraded coastal system; this setting
is suggested by the abundance of erosion
terraces (shore platforms) excavated into the
intensely fractured limestone bedrock, and by
the lack of significant alluvial/fluvial systems on
the small calcareous paleoisland.
Respectively from the shoreline toward the
basin, four main depositional zones were
differentiated in the Matera example (Pomar &
Tropeano, 2001) (fig 2):
- (a) the beachface: it was the zone affected by
breaking waves and wave-swash processes;
this zone is recorded by cobble-pebbly clastsupported facies organized in a few decimetres
thick beds which are horizontally to gently
seaward dipping (5° up to 10°). (a’) boulder
wedges replaced the beachface on cliffed
coasts.
- (b) the shoreface: it was a gently inclined
zone dominated by wave traction and where,
during large wave activity, sediments were
swept seaward; this zone is recorded by
pebble to granule clast-supported facies which
fig 3 - Parasequences and simple sequences, according to Pomar & Tropeano (2001)
38
pass seaward to granule and coarse-sand
facies; shoreface deposits are organized in
subhorizontal to gently seaward dipping thin
beds (1°-2° up to 5°).
- (c) the transition slope: it was an up to 35°
steep zone located to the seaward of the
shoreface, just below the major wave-base
level; it is recorded by laterally extensive and
parallel to the paleoshoreline seaward dipping
large clinoforms mainly made up of granule and
sand facies.
- (d) the offshore: it was the area dominated by
low water-energy conditions and progressive
seaward sediment starving, in which
bioturbation was significant; it is recorded by
fine-grained sediments (medium to fine sands)
containing rhodoliths, bryozoan, brachiopods
and echinoids.
The most conspicuous and volumetrically
important facies related to this depositional
system are the transition-slope deposits which
form large-scale, high-angle, cross-bedded
lithosomes. They derived from avalanches
of sediment, swept onto a depositional slope
below wave-base from the shoreface zone by
storm waves and wind-driven currents. The
transition slope represented one sector of
the coastal-equilibrium profile and migrated
according to evolution of the depositional
system; its deposits cannot be confused
as a result of bedforms migration (i.e. large
sandwaves).
Stratigraphic architecture and sequence
stratigraphy
Three types of building blocks are recognized:
embryonic
parasequences,
mature
parasequences and simple sequences (Pomar
& Tropeano, 2001) (fig 3). Parasequences
formed during stillstands of sea level and
simple sequences during high-frequency cycles
of relative change of sea level. Embryonic
parasequences represent thin accretional
units which lack transition-slope deposits.
Base level for the depositional system was the
wave base which governed the position of the
shoreface zone. During slow relative sea-level
rises (still-stand + subsidence) also the base
level rose, and there was space both for the
aggradation of the shoreface deposits and for
the progradation of transition-slope deposits
with the growth of sigmoidal bodies (mature
parasequence). During relative sea-level falls
(fall > subsidence) also base level went down,
and the shoreface zone became an eroded and
bypassed zone of the system; progressively,
former shoreface deposits and the top of
former clinobeds were cancelled while a
steeper transition-slope prograded (FSST of
simple sequence); an internal downlap surface
fig 4 - Wheeler diagrams referred to Matera accretional units, according to Pomar & Tropeano, (2001)
39
inside the foreset deposits put in evidence this
base-level fall (fig 4).
Beneduce P., Festa V., Francioso R., Schiattarella
M. & Tropeano M. (2004) - Conflicting drainage
patterns in the Matera Horst area, Southern Italy.
Phys. and Chem. of the Earth, 29, 717-724.
Ciaranfi N., Ghisetti F., Guida M., Iaccarino G.,
Lambiase S., Pieri P., Rapisardi L., Ricchetti
G., Torre M., Tortorici L. & Vezzani L. (1983) Carta neotettonica dell’Italia Meridionale. C.N.R.,
Pubbl. n.515 del Prog. Final. Geodin.: 62pp.
Coe A.L. (ed.) (2003) - The sedimentary record of
sea-level changes. Cambridge University Press,
pp 288
Doglioni C., Mongelli F. & Pieri P. (1994) - The
Puglia uplift (SE Italy): an anomaly in the foreland
of the Apenninic subduction due to buckling of a
thick continental lithosphere. Tectonics, 13, 5,
1309–1321.
Emery D. & Myers K.L. (eds.) (1996) - Sequence
stratigraphy. Blackwell, 297.
Iannone A. & Pieri P. (1979) - Considerazioni
critiche sui “Tufi calcarei” delle Murge. Nuovi dati
litostratigrafici e paleoambientali. Geog. Fis. e
Din. Quat., 2, 173–186.
Plint A. G. (1988) - Sharp-based shoreface
sequences and “offshore bars” in the Cardium
Formation of Alberta: their relationship to relative
changes in sea level. In: C. K. Wilgus, B. S.
Hasting, C. G. St. C. Kendall, H. W. Posamentier,
C. A. Ross, and J. C.Van Wagoner, eds., Sealevel changes: an integrated approach: SEPM
Sp. Publ. 42, 357–370.
Posamentier H.V. & Allen G.P. (1993) - Varaibility of
the sequence stratigraphic model: effects of local
basin factors. Sed. Geol. 86, 91-109.
Tropeano M., Pomar L. & Sabato L (2001) - The
offlap break position versus sea-level: a
discussion. Relazione orale. Riassunti 1st annual
conference IGCP 464 “Continental shelves
during the last glacial cycle”, Hong Kong, 25-28
ottobre 2001. 53-54.
Tropeano M. & Sabato L. (2000) - Response of
Plio-Pleistocene mixed bioclastic-lithoclastic
temperate-water carbonate systems to forced
regression: the Calcarenite di Gravina Formation,
Puglia, SE Italy. In: D. Hunt and R. L. Gawthorpe,
eds., Sedimentary response to forced regression:
Geol. Soc. Sp. Publ. 172, 217–243.
Tropeano M., Sabato L. & Pieri P. (2002) - Filling
and cannibalization of a foredeep: the Bradanic
Trough, southern Italy. In: Jones S.J. & Frostick
L.E. (eds.) “Sediment flux to basins: causes,
controls and consequences”. Geol. Soc..Spec.
Publ., 191, 55-79.
Training of sequence stratigraphy
Between the end of the ‘80s and the beginning
of ‘90s, a series of works (led by Plint,
Posamentier, Vail, Van Wagoner and Walker,
among others) described marginal-basin
successions and provided models to apply
sequence-stratigraphic concepts to sedimentary
cycles induced by high-frequency relative sealevel changes. Definitions of parasequences
and simple sequences, which now represent
key words for sequence stratigraphy concepts,
originated both from those works and models
(for historical overviews see: Emery & Myers,
1996; Coe, 2003). These models became
the working base for metre-scale sequencestratigraphy studies referred either to
outcropping or subsurface deposits.
Many of these sequence stratigraphy concepts
may be applied in the Matera example both to
each building block (accretional units) and to
their stacking. Comparisons/contrasts between
sequences and parasequence boundaries,
maximum flooding and transgressive surfaces,
still-stand and falling-stage systems tracts,
represent some of the arguments which may
be discussed in the field. Internal downlap
surfaces inside transition-slope deposits permit
to discriminate the presence of “attached”
FSST-LST (sensu Ainsworth & Pattison, 1994)
and to discuss alternative models regarding the
origin of the “sharp based sequences” (sensu
Plint, 1988) and the nature of the “healing
phase” deposits (sensu Posamentier & Allen,
1993).
Moreover, the retrogradational stacking pattern
(backstepping), which characterizes the
Calcarenite di Gravina Formation in Matera,
simulates an amplified and well developed TST
of a 3rd order cycle.
References
Ainsworth R. B. & Pattison S. A. J. (1994) - Where
have all the lowstands gone? evidence for
attached lowstand systems tracts in the Western
Interior of North America. Geol., 22, 415–418.
40
Thirty years of Sequence Stratigraphy:
Applications, Limits and Prospects
POSTER PROGRAMME
TST - HST
HST
TST
incised valley
fills
HST
HST TST
FSST
LST
SMST
TST
LST
sb1
older sequence
FSST
sb2
sb1
sb1
Thirty years of Sequence Stratigraphy: Applications, Limits and Prospects - 2 October 2006 - Bari - Italy
CYCLICITY IN THE LOWER AND MIDDLE PLEISTOCENE SAN LORENZO
LACUSTRINE SUCCESSION OF THE SANT’ARCANGELO BASIN (SOUTHERN
APENNINES, ITALY): MAGNETIC, PALYNOLOGIC AND SEDIMENTARY SIGNALS
Andrea Albianelli1, Adele Bertini1, Claudia Lombardi2, Massimo Moretti3,
Giovanni Napoleone1 and Luisa Sabato3
1
Dipartimento di Scienze della Terra, Università di Firenze
2
Dipartimento di Geologia, Università di Siena
3
Dipartimento di Geologia e Geofisica, Università di Bari
The Sant’Arcangelo Basin is an Apennines
satellite basin, containing four depositional
sequences, late Pliocene to middle Pleistocene
in age (Pieri et al., 1996). Each sequence
is bounded by unconformities (mainly
progressive in origin), and shows evidence
of synsedimentary tectonics (Caldara et al.,
1988; Pieri et al., 1994; Vitale, 1996; Zavala,
2000; Moretti & Sabato, 2006). The lower two
sequences are mainly composed of deltaic to
shelf systems; the third sequence developed in
two different and adjacent sectors of the basin
and comprises deltaic to shelf systems in the
eastern sector and fluvio-lacustrine systems
in the western one (San Lorenzo Sequence).
The fourth sequence unconformably overlies
the older ones and is composed of alluvial
sediments.
The lacustrine deposits of the San Lorenzo
Sequence provide detailed records of
magnetic and pollen signals that reveal the
history of both magnetic reversals and orbital
variations, together with the vegetational and
climatic changes. Vital to the reconstruction
of this history has been the establishment of
a high resolution chronology in the Apennines
intramontane basins, based on the magnetic
reversal stratigraphy tied to the geomagnetic
polarity time scale (Sabato et al., 2005). These
dates fix critical boundaries that, aided here
by accumulation rates higher than 0.5 m/ky,
provided 2 ky resolution to the timing of climate
changes around the early-middle Pleistocene
boundary. In fact, the lacustrine succession
here examined also recorded variations in all
magnetic parameters measured, within which
the magnetically defined precessional units, with
mean thicknesses of 30 m, seem modulated in
amplitude by the eccentricity cycles since the
Jaramillo chron. We demonstrate the cyclicity
in the susceptibility of a more than 200 m
thick profile extending from shortly before the
Jaramillo to the onset of Brunhes. The pollen
record shows a cyclical pattern too as testified
by the alternations between forest and open
vegetation communities which in turn reflect
moister and drier climate oscillations. Also the
lithologic variations seem to record the same
fluctuations related to humid and dry intervals.
The examined interval represents a window
through a long gap in the history of the climate
changes in the Apennines intramontane basins
between the record of 1.5 my measured in the
Northern Apennines, mainly in the lower Upper
Valdarno profile and complemented by that of
the Colfiorito basin up to the Jaramillo, and
the late mid-Pleistocene ones in the Southern
Apennines (e.g. Bertini, 2003; Napoleone et
al., 2003).
References
Bertini A. 2003. Early to Middle Pleistocene changes
of the Italian flora and vegetation in the light of
a chronostratigraphic framework. Il Quaternario,
16 (1bis): 19-36.
Caldara, M., Loiacono, F., Morlotti, E., Pieri, P.,
Sabato, L. 1988. I depositi pliopleistocenici della
parte Nord del Bacino di S. Arcangelo (Appennino
lucano): caratteri geologici e paleoambientali.
Mem. Soc. Geol. It., 41, 391-410.
Moretti M., Sabato L. 2006. Recognition of trigger
mechanisms for soft-sediment in the Pleistocene
lacustrine deposits of the Sant’Arcangelo Basin
(south Italy): seismic shock vs. overloading.
Sedimentary Geology.
Napoleone G., Albianelli A., Azzaroli A., Bertini A.,
Magi M., Mazzini M. 2003. Calibration of the
Upper Valdarno Basin to the plio-Pleistocene for
correlating the Apennine continental sequences.
Il Quaternario, 16 (1bis): 131-166.
Pieri, P., Sabato, L., Loiacono, F., Marino, M.
1994. Il bacino di piggyback di Sant’Arcangelo:
evoluzione tettonico-sedimentaria. Boll. Soc.
Geol. It., 113 (2), 465-481.
Pieri, P., Sabato, L., Marino, M. 1996. The PlioPleistocene piggyback Sant’Arcangelo Basin:
tectonic and sedimentary evolution. Notes et
Mémoires du Service géologique du Maroc, 387:
195-208.
Sabato L., Bertini A., Masini, M., Albianelli A.,
Napoleone G. Pieri P. 2005. The lower and
middle Pleistocene geological record of the San
Lorenzo lacustrine sequence in Sant’Arcangelo
41
Basin (Southern Apennines, Italy). Quaternary
International, 131: 59-69.
Vitale, G. 1996. Evoluzione tettonica e stratigrafica
dal passaggio Miocene-Pliocene all’attuale
del sistema catena-avanfossa lungo il fronte
bradanico-ionico. Unpublished Ph.D. Thesis,
Bari University, Italy: 159pp.
Zavala, C. 2000. Stratigraphy and sedimentary
history of the Plio-Pleistocene Sant’Arcangelo
Basin, Southern Apennines, Italy. Rivista Italiana
di Paleontologia e Stratigrafia, 106 (3): 399-416.
42
Thirty years of Sequence Stratigraphy: Applications, Limits and Prospects - 2 October 2006 - Bari - Italy
STRATIGRAPHIC ARRANGEMENT OF THE “REGRESSIVE COASTAL DEPOSITS” OF
THE BRADANIC TROUGH (BASILICATA, SOUTHERN ITALY): SUBSIDENCE, UPLIFT,
AND HIGH-FREQUENCY SEA-LEVEL CHANGES
Antonietta Cilumbriello1, Luisa Sabato1, Marcello Tropeano1, Salvatore
Gallicchio1, Antonio Grippa2 and Piero Pieri1
1
Dipartimento di Geologia e Geofisica, Università di Bari. Via Orabona 4, BARI (Italy)
2
Dipartimento di Scienze Geologiche, Università della Basilicata, POTENZA (Italy)
middle of the Bradanic Trough near the chain
border (Banzi-Genzano area), are Emilian in
age and prograde towards the E-NE (fig. 1),
whilst younger deposits prograde either to
the N (towards the central Adriatic coast), or
to the E (towards the Manfredonia Gulf), or to
the SE (towards the Taranto Gulf) (Tropeano
et al., 2002). The present work regards the
stratigraphic arrangement of the “Regressive
coastal deposits” which, starting from the
Banzi-Genzano area, progressively develop
towards the Taranto Gulf.
In the Banzi-Genzano area the “Regressive
coastal deposits”, up to 150 meters thick, are
represented by a mainly conglomeratic unit
The outcropping part of the in-fill succession of
the Bradanic Trough (the Southern Appennines
foredeep) is represented by a Pleistocene
regressive succession made up of silt-clay
deposits (Argille subappennine Formation)
followed by mainly sandstone-conglomerates
sediments. These latter named “Regressive
coastal deposits” by Pieri et al. (1996),
represent the top of the foredeep successions
and their thickness varies from a few metres
up to over 100 metres; facies belong to
paralic, deltaic and/or alluvial environments
(Tropeano et al., 2002). According to Pieri
et al. (1994; 1996), the highest and oldest
“Regressive coastal deposits”, located in the
Fig. 1 - Paleogeographic maps showing the development of the “Regressive coastal deposits”
(Tropeano et al., 2002).
43
Fig. 2 - Schematic stratigraphic configuration observed in the “Regressive coastal deposits” of the Bradanic Trough.
in the northwestern sector which interfinger
whit a mainly sandy unit, better developed
in the southeastern sector of the area. The
conglomeratic unit is made up of subhorizontal
beds, continental in origin, passing to
wedging and clinostratified bodies, deltaic
in origin, which alternate with sandy bedset
toward the SE. The sandy unit is made up of
subhorizontal beds, shallow marine (shoreface)
in origin. Development of gravelly beds is
considered linked to depositional systems
prograding and aggrading during relative
lowstand stages, while sandy marine deposits
represent depositional systems replacing the
previous ones during relative trasgression and
highstand of the sea-level. The “Regressive
coastal deposits” of the Banzi-Genzano area
show an aggradational stratigrafic pattern
induced by high-frequency sea-level changes
in a sector of the Bradanic Trough where the
rate of sedimentation compensated the rate of
subsidence (Cilumbriello, 2004; Cilumbriello et
al., 2005; 2006).
Toward the SE of the Banzi-Genzano area,
in the adjacent Irsina-Grassano area, the
outcropping “Regressive coastal deposits”
(physically separated from those previously
described) are arranged into prograding wedges
whose top depositional surface progressively
falls in elevation along the progradation dip
(Tropeano et al., 2002). Erosionally based
wedges, commonly characterized by gravelly
delta deposits, alternate with transitionally
based ones, characterized mainly by aggrading
deposits which from bottom to top pass
from offshore-transition facies of the Argille
subappennine Formation up to shoreface,
beach and, in some places, to alluvial facies
(Sabato, 1996; Sabato et al., 2004). This
stratigraphic arrangement is considered the
result of sandy and sandy-gravelly deposition
during relative highstand of the sea-level, and
gravelly deposition during relative falls and
lowstands of the sea-level; the downwardshifting configuration that characterizes the
“Regressive coastal deposits” in Irsina and
Grassano area is interpreted as deriving
from high-frequency sea-level changes in an
uplifting context (Tropeano et al., 2002; Sabato
et al, 2004).
In the southern part of the Bradanic Trough the
“Regressive coastal deposits” are represented
by the well-known “marine terraced deposits”
of Metaponto (Vezzani, 1967; Bruckner, 1980)
which correspond to wedges with a complex
internal stratigraphic arrangement of sandy and
gravelly facies (shallow-marine to continental in
origin) induced by very high-frequency relative
44
sea-level changes. Wedges shifted during time
up to the present-day coastal area in responce
to the interference between high-frequency
sea-level changes and uplift of the area. A
downward-shifting configuration produced
but it differs from that observed in the IrsinaGrassano area since each wedge is dethached
from the others.
Tesi di Laurea, Università della Basilicata, 90pp.
CILUMBRIELLO A., SABATO L., & TROPEANO M. (2005) – I
depositi infrapleistocenici di avanfossa nelle aree
di Banzi e Genzano di Lucania: vincoli stratigrafici
sull’evoluzione del sistema catena-avanfossa
in Appennino lucano. Giornata di Studio in
memoria di Alfredo Jacobacci: Evoluzione delle
conoscenze geologiche dell’Appennino apulocampano e tosco-umbro-marchigiano, Roma, 7
novembre 2005.
CILUMBRIELLO A., SABATO L., & TROPEANO M. (2006)
– Evidenze stratigrafiche delle ultime fasi di
subsidenza della Fossa bradanica prima del
sollevamento quaternario: la serie sabbiosoghiaiosa nell’area di Banzi e Genzano di
Lucania (Basilicata). Convegno: Il sollevamento
quaternario nella penisola italiana e nelle aree
limitrofe, Roma 6-8 febbraio 2006.
COE A. (2003) – The sedimentary Record of sealevel change. Cambridge, University press.
LAZZARI M. & PIERI P. (2002) – Modello stratigraficodeposizionale della successione regressiva
infrapleistocenica della Fossa bradanica nell’area
compresa tra Lavello, Genzano e Spinazzola.
Mem., Soc., Geol., It., 57, 231-237.
MASSARI F. & PAREA G. C. (1988) – Progradational
gravel beach sequences in a moderate-to
high-energy, microtidal marine environment.
Sedimentology, 35, 881-913.
PIERI P., SABATO L. & TROPEANO M. (1994) – Evoluzione
tettonico-sedimentaria della Fossa bradanica
a sud dell’Ofanto nel Pleistocene. In: Guida
alle escursioni. Congresso Soc. Geol. It., Bari.
Quaderni Bibl. Prov. Matera, 15, 35-54.
PIERI P. SABATO L. & TROPEANO M. (1996) – Significato
geodinamico dei caratteri deposizionali e
strutturali della Fossa bradanica nel Pleistocene.
Mem., Soc.,Geol.,It., 51, 501-515.
POSAMENTIER H. W. & MORRIS W. R. (2000) – Aspects
of the stratal architecture of regressive deposits.
Sedimentary Responses to Forced Regressions
172, 19-46.
SABATO L. (1996) – Quadro stratigraficodeposizionale dei depositi regressivi nell’area
di Irsina (Fossa bradanica). Geologica Romana,
32, 219-230.
SABATO L. (2004) – Problemi di cartografia geologica
relativa ai depositi quaternari del F°471 “Irsina”.
Il Conglomerato di Irsina: mito o realtà? Il
Quaternario, Italian Journal of Quaternari
Sciences, 17 (2/1), 391-404.
TROPEANO M., SABATO L. & PIERI P. (2002) – Filling and
cannibalization of a foredeep: Bradanic Trough,
southern Italy. Geological Society of London,
Special Publications, 191, 55-79.
VEZZANI L. (1967) – I depositi plio-pleistocenici del
litorale ionico della Lucania. Atti Accademia
Gioenia Scienze Naturali, 18, 159-180.
A preliminary interpretation about the three
different stratigraphic configuration observed
in the Bradanic Trough (aggradation/
backstepping, downward-shifting of attached
wedges, and downward shifting of detached
wedges) is that they produced in responce
of variation in the geodynamic trend (fig.
2). Aggradation/backstepping configuration
produced during a gentle relative sea-level
rise (TST-HST) when depositional systems
developed due to the interference between
high-frequency
sea-level
changes
and
(probably) slow rate of subsidence. Downwardshifting of attached wedges produced during
a gentle relative sea-level fall (a low order
late HST towards FSST) when depositional
systems developed due to the interference
between high-frequency sea-level changes
and (probably) slow rate of uplift. Downwardshifting of detached wedges produced during
a stronger relative sea-level fall (FSST) when
depositional systems developed due to the
interference between high-frequency sealevel changes and high rate of uplift. The two
described downward-shifting configurations
simulate respectively an attached FSST and
a detached FSST, the first being produced by
higer rate of sediment supply or a slower rate of
relative sea-level fall (according to Coe, 2003,
after Posamentier & Morris, 2000). It cannot
be excluded that differences in the two FSST
configurations could have been produced also
by variation in amplitudes of high-frequency
sea-level changes.
References
BRUCKNER H. (1980) – Marine terrasen in Süditalien.
Eine quartärmorphologische. Studie über das
Kustentiefland von Metapont. Düsseldorfer
Geographische Schriften, 14, 235pp.
CILUMBRIELLO A. (2004) – Caratteri stratigrafici dei
depositi regressivi pleistocenici della Fossa
bradanica nell’area di Banzi e Genzano di
Lucania(Basilicata). Università della Basilicata.
45
46
Thirty years of Sequence Stratigraphy: Applications, Limits and Prospects - 2 October 2006 - Bari - Italy
THE INTERPLAY AMONGST TROPHIC REGIME, CARBONATE FEEDBACK SYSTEM
AND CHANGES IN STRATIGRAPHIC ACCOMMODATION SPACE: AN INVESTIGATION
BASED ON THE PALAEOECOLOGICAL ANALYSIS OF THE MICROBENTHIC
ASSEMBLAGES IN TWO CASE STUDIES OF THE EARLY CRETACEOUS SHALLOWWATER CARBONATES
Dario De Benedictis
Dipartimento di Geologia e Geofisica, Università degli Studi di Bari
Benthic foraminifera and calcareous algae
(especially dasycladaceans) played a very
important role during the Early Cretaceous
time as suppliers of large volumes of
carbonate material in shallow-water platform
settings within the carbonate factory system.
The latter is defined as the totality of the
carbonate-producing organisms (fauna and
flora) that provides sediments to platform
top environments. Changes in climatic and
oceanographic conditions strongly control type
and development of such a complex system by
influencing environmental factors of organisms’
life habitats. In other words, environmental
factors are the input data of the carbonate
system or the framework within which
sedimentary succession (the output) forms.
on the M.te Faito and a 270-m thick section
nearby Pietraroja) (De Castro, 1962, 1964a,
b; D’Argenio, 1967; Cherchi et al., 1978;
Robson, 1987; D’Argenio et al.,1987, 1988; De
Benedictis, 2005); both were deposited in the
carbonate platform-top settings of the southern,
continental Western Tethys margin.
An integrated sedimentological/palaeontological
study showed that the successions deposited
within the infralittoral belt of the carbonate
platform, which was characterized by a mosaic
of sub-settings: protected/restricted lagoons,
subtidal channels, protected mud plains, sand
shoals and bars, and secondarily low-relief
supratidal highs and intertidal banks.
The palaeoecological analysis of the
microbenthic assemblages, whose definition
was based on the determination of the
component specimens (foraminifera, algae,
ostracods, ?corals, mollusc shell fragments)
and their relative abundance, allowed to
determine the environmental factors affecting
benthic habitats (oxygen, food, water
clearness, salinity, water depth, sedimentation
rate and hydrodynamic energy) in space
and time. Facies-breaking and facies-related
microbenthic assemblages (the record of the
microbenthic communities) characterize the
restored depositional scenario.
Since
microbenthic,
calcareous-shelled
organisms, living onto or within the substrate
and being part of the sediment itself,
microbenthic fossil assemblages are the direct
link between the input environmental factors
and the carbonate sedimentary succession
– that is, the output of the carbonate feedback
system.
The palaeoecological analysis (mainly based
on the foraminiferal functional morphology;
e.g. Hottinger, 1987, 1997, 2000a, b) of the
recognized microbenthic assemblages as
well as the sedimentological and microfacies
study may help the stratigraphers to identify
the environmental factors, and their changes
in space and time, that controlled the life of the
original communities within the depositional
environment. This allowed to understand the
interplay among the microbenthic communities,
their controlling factors and the carbonate
feedback system, as well as the mechanisms
that drove their changes through the studied
stratigraphic interval.
Field work was carried out on a number of
two Barremian-Aptian (Early Cretaceous)
carbonate successions, cropping out in
southern Apennines (a 90-m thick section
Palaeoecological analyses demonstrated that
in both of the studied successions the variation
in trophic regime was the main mechanism
controlling the succession of the microbenthic
communities (De Benedictis, 2005), and,
therefore, the carbonate feedback system.
Such a variation is firstly caused by changes
of relative sea-level since they influence water
circulation on the carbonate platform and
nutrient transport (from the basin and from the
subaerially-exposed areas) (e.g., Homewood,
1996; Pittet et al., 2000, 2002) together with
wave base depth, subaerial weathering and
photic zone depth.
47
Bibliography
Homewood, P.W., 1996. The carbonate feedback
system: interaction between stratigraphic
accommodation, ecological succession and the
carbonate factory. Bull. Soc. géol. France, 167:
701-715.
Hottinger, L.C., 1987. Conditions for generating
carbonate platforms. Mem. Soc. Geol. It., 40:
265-271.
Hottinger, L.C., 1997. Shallow benthic foraminiferal
assemblages as signals for depth of their
deposition and their limitations. Bull. Soc. géol.
France, 168: 491-505.
Hottinger, L.C., 2000a. Functional morphology of
benthic foraminiferal shells, envelopes of cells
beyond measure. Micropaleontology, 46: 57-86.
Hottinger, L.C., 2000b. Adaptations of the
foraminiferal cell to life in shallow carbonates
environments. In: Crisi biologiche, radiazioni
adattative e dinamica delle piattaforme
carbonatiche, Accad. Naz. Sci. Lett. Arti di
Modena, Collana di Studi, 21 (2000): 135-140.
Pittet, B., Strasser, A., and Mattioli, E., 2000.
Depositional
sequences
in
deep-shelf
environments: a response to sea-level changes
and shallow-platform carbonate productivity
(Oxfordian, Germany and Spain). J. Sed. Res.,
70: 392-407.
Pittet, B., van Buchem, F.S., Hillgärtner, H., Razin,
P., Grötsch, J., and Droste, H., 2002. Ecological
succession, palaeoenvironmental change, and
depositional sequences of Barremian-Aptian
shallow-water carbonates in northern Oman.
Sedimentology, 49: 555-581.
Cherchi, A., De Castro, P., and Schroeder, R., 1978.
Sull’età dei livelli a Orbitolinidi della Campania e
dell Murge Baresi (Italia meridionale). Boll. Soc.
Natur. Napoli, 87: 363-385.
D’Argenio, B., 1967. Le facies litorali mesozoiche
nell’Appennino Meridionale. Boll. Soc. Nat.
Napoli, 75: 497-552.
D’Argenio, B., Ferreri, V., and Ruberti, D., 1987.
Cyclic versus episodic deposition in a carbonate
platform sequence. Lower Cretaceous of Matese
Mountains, southern Apennines. Mem. Soc.
Geol. It., 40: 375-382.
D’Argenio, B., Ferreri, V., and Ruberti, D., 1988. Cicli,
ciclotemi e tempestiti nei depositi carbonatici
aptiani del Matese (Appennino campano). Mem.
Soc. Geol. It., 41: 761-773.
De Benedictis, D., 2005. Palaeoecology of benthic
foraminiferal assemblages of Barremian-Aptian
(Early Cretaceous), shallow-water platform
carbonates in southern Apennines (Campania
district, southern Italy). Unpublished PhD Thesis.
University of Bari. 127 pp.
De Castro, P., 1962, Nuove osservazioni sul livello
ad Orbitolina in Campania. (Nota preliminare).
Boll. Soc. Nautr. Napoli, 71: 103-135.
De Castro, P., 1964a. Cuneolina scarsellai n.sp. del
Cretaceo dell’Appennino meridionale. Boll. Soc.
Nat. Napoli, 72: 71-76.
De Castro, P., 1964b. Su di un nuovo foraminifero del
Cretacico inferiore dell’Appennino meridionale.
Boll. Soc. Nat. Napoli, 73: 55-71.
48
Thirty years of Sequence Stratigraphy: Applications, Limits and Prospects - 2 October 2006 - Bari - Italy
SOME FEATURES OF THE PLIOCENE – LOWER PLEISTOCENE SEQUENCE OF THE
SOUTHEASTERN SALENTO.
Marco Delle Rose
CNR, IRPI, via G. Amendola 122/i, 70126 Bari
Tel. 080 5929581; Fax 0805929611; e-mail: [email protected]
During Pliocene, the Mediterranean Sea was
affected by large scale geodinamic events and
a number of periods of sub-polar conditions
presaging the entry of northern fauna. Pliocene
is probably the most questionable series of the
whole Salento geological record. Although the
main lithological features have been recognized
by DE GIORGI (1922), its sedimentological
arrangement has not been well defined. Two
lithostratigraphic units have recognized: Leuca
Formation and Uggiano la Chiesa Formation.
Nevertheless, their chronostratigraphic context
as well as their relationships with younger
Quaternary deposits, are object of several
interpretations (BOSSIO et alii, 1987; BOSELLINI
et alii, 1999; MASSARI & D’ALESSANDRO, 2000;
D’ALESSANDRO et alii, 2004; DELLE ROSE, 2006).
Geological surveys performed through the
southwestern Salento peninsula allow us to
recognize five lithological facies (unformal units
or stratigraphic levels) linked to Mediterranean
paleo-environmental and paleo-climatology
events (table 1 and figure 1).
Chaotic assemblage consists of blocks,
breccias and pebbles within calcarenitic or
calciruditic matrix and includes thin limestone
lens. Marlstones are massive and contain
coarse clasts, whereas glauconitic siltstones
consist of bioturbated calcareous silty-sand
beds. They are truncated by an erosive surface
showing holes filled by phosphatized clasts.
Phosphatized calcirudite contains a number
of squashed marly inclusions and shows
a three-folded partition (reverse grain-size
grading basal portion; middle one contains
a dense detritus component; normal grainsize grading upper portion) which suggest
intra-platform grain flow re-sedimentation
processes. Calcarenites and calcilutites consist
of fossiliferous intensively bioturbated coarse
to fine-grained beds bounded by diastems,
containing Arctica islandica at the top.
The sedimentological features of the chaotic
assemblage indicate final Miocene exposed
ridges
dismantling
and
post-Messinian
Salinity Crisis shallow marine deposition.
The interbedded lens of limestones could
represent deposits of a transitional continentsea environment subject to intense evaporation
under warm and dry climate (MASSARI &
D’ALESSANDRO, 2000). The Early Pliocene
Inundation (IACCARINO et alii, 1999) deepened
the Salento shelf and leaded to the marlstones
deposition probably at epibathyal paleo-depth.
Glauconitic siltstones attest a relatively long
phase of very low rate of sedimentation, in
accordance with the general Mediterranean
depositional setting during the lower-middle
Pliocene (CITA et alii, 1999); the deposition of
the aforementioned facies could be stopped not
before than the upper Piacenzian.
The encrustations of the clasts forming the
Table 1 - Salento Pliocene lithological facies
FACIES
LITERATURE NAMES
Calcarenites and Uggiano la Chiesa Fm (BOSSIO et alii, 1987);
calcilutites
subunit 2a (D’ALESS ANDRO et alii, 2004)
phosphatized
basal conglomerate (BOSSIO et alii, 1987;
calcirudite
BOSELL INI et alii, 1999); terrestrial conglomerate
(MASSARI & D’ALESSANDRO , 2000)
Glauconitic
Leuca Fm (BOSSIO et alii, 1987); glauconitic
siltstones
mudstone (BOSELL INI et alii, 1999); glauconitic
silty sand (MASSARI & D’ALESSANDRO, 2000)
Marlstones
Leuca Fm (BOSSIO et alii, 1987); Trubi Fm
(BOSELLINI et alii, 1999)
Chaotic
Leuca Fm (BOSSIO et alii, 1987, 2001); Leuca
assemblage
Breccia (BOSELL INI et alii, 1999); subunit 1a
(D’ALESSANDRO et alii, 2004)
49
AGE
GelasianSanternian
Gelasian
ZancleanPiacenzian
ZancleanPiacenzian
Zanclean
Fig. 1 - Stratigraphic sections of the investigated areas. A - pre Pliocene; B - paleosol; C - Chaotic
assemblage; D - undulated calcarenite beds; E - limestone and calcarenite lens; F - Marlstones; G
- Glauconitic siltstones; H - Phosphatized calcirudite; I - squashed marly inclusions; L - bioturbated
calcarenites and calcilutites; M - Arctica islandica; N - Strombus coronatus; O - Terebratula scillae; P
- sands; Q - pelites. Biostratigraphic markers tentatively positioned after BOSSIO et alii (1987, 2001),
RIO et alii, (1998), MASSARI & D’ALESSANDRO (2000), PATACCA & SCANDONE (2004), DELLE ROSE (2006).
skeleton of the phosphatized calcirudite
probably developed below the euphotic zone
and above the thermocline depths, i.e. between
the deepest inner shelf and the shallowest
middle shelf. The calcarenites and calcilutites
were supplied from an expansive source area
located to the north west of Salento as far as
the Murge (DELLE ROSE, 2006). Sediments
were piled toward Salento, reworked, sorted
and transported by currents within the shelf.
During the Gelasian, the flat land between
Salento and Murge have been probably a
inner shelf/ramp where erosion and off shore
sediment transport was higher than carbonate
production. Thin inner shelf/ramp successions
draped local depressions, such as the Novoli
graben (D’ALESSANDRO et alii, 2004).
Calcarenites and calcilutites was deposited
within a middle shelf/ramp, where the
sediments derived from the inner zone and
relict ones were bioturbated and reworked by
waves. They can be related to the Calcarenite
di Gravina Fm, widespread all over Murge and
Bradanic Trough (TROPEANO & SABATO, 2000).
The results carried out by southeastern Salento
surveys, can be probably extended also at NW
and NE sectors of the Lecce province (figure
1), where the occurrence of Arctica islandica
shell concentrations and the presence of a
phosphatized calciruditic level have been
respectively detected (DELLE ROSE & MEDAGLI, in
press; DELLE ROSE et alii, 2006).
In conclusion, the southeastern Salento
Pliocene
forms
a
sequence
which
records five stratigraphic levels related to
Mediterranean events such us: the late
Messinian Mediterranean drawdown; the
early Pliocene paleo-depth inundation; the
lower-middle Pliocene stage of very low rate of
sedimentation; the about 2.5 My cooling interval
and/or the southern Apennines middle-upper
Pliocene tectonic phase and, at the boundary
with the Pleistocene, the arrival of the “northern
guests” (DELLE ROSE, 2006). At least along the
southeastern Salento, Pliocene is not formed by
two sedimentary cycles as reported in literature
(BOSSIO et alii, 1987). The chaotic assemblage
represents the Transgressive System Tract
relative to the fast early Pliocene sea level
rise; marlstones and glauconitic siltstones are
the condensed deposits linking the maximum
flood surface, whereas the overlying erosional
surface represents an unconformity marking
a gap in the sequence. Finally, calcarenites
and calcilutites constitute the High Stand Tract
relative to the sea level dropping.
50
References
Thalassia Salentina, 29, 77-99.
DELLE ROSE M., PAPPAFICO G., RESTA F. (2006) –
Problematiche stratigrafiche e cartografiche del
Pliocene ad est di Lecce. Riassunti 83° Congr.
Soc. Geol. It., Chieti, settembre 2006, 12-16
117-120.
IACCARINO S., CASTRADORI D., CITA M.D., DI STEFANO
E., GABOARDI S., MCKENZIE J.A., SPEZZAFERRI S.,
SPROVIERI R. (1999) - The Miocene-Pliocene
boundary and the significance of the earliest
Pliocene flooding in the Mediterranean. Mem.
Soc. Geol. It., 54, 109-131.
MASSARI F., D’ALESSANDRO A. (2000) - Tsunamirelated scour-and-draper undulations in Middle
Pliocene restricted-bay carbonate deposits
(Salento, south Italy). Sedimentary Geology,
135, 265-281.
PATACCA E., SCANDONE P. (2004) - The PlioPleistocene thrust belt-foredeep system in the
Southern Apennines and Sicily (Italy). IGC 32
Soc. Geol. It. sp. vol., 93-129.
RIO D., SPROVIERI R., CASTRADORI D., DI STEFANO
E. (1998) - The Gelasian stage (Upper
Pliocene): A new unit of the global standard
chronostratigraphic scale. Episodes, 21, 82-87.
TROPEANO M., SABATO L. (2000) - Response of
Plio-Pleistocene
mixed
biclastic-lithoclastic
temperate-water carbonate systems to forced
regression: the Calcarenite di Gravina Formation,
Puglia, SE Italy. In: HUNT D., GAWTHORPE R.L.,
Sedimentary Responses to Forced Regression.
Geological Soc. London, sp. Publ., 172, 217243.
BOSELLINI A., BOSELLINI F.R., COLALONGO M.L., PARENTE
M., RUSSO A., VESCOGNI A. (1999) - Stratigraphic
architecture of the Salento coast from Capo
d’Otranto to S. Maria di Leuca (Apulia, southern
Italy). Riv. It. Paleont. Strat., 105, 397-416.
BOSSIO A., GUELFI F., MAZZEI R., MONTEFORTI B.,
SALVATORINI G. (1987) - Precisazione sull’età della
Formazione di Uggiano la Chiesa nella zona di
Otranto (Lecce). Quad. Ric. Centro St. Geotec.
Ing., 11, 175-194.
BOSSIO A., MAZZEI R., MONTEFORTI B., SALVATORINI G.
(2001) - Note illustrative alla carta geologica
della zona di S. Maria di Leuca. Soc. Tosc. Sc.
Nat., 107, 97-163.
CITA B.M., RACCHETTI S., BRAMBILLA R., NEGRI M.,
COLOMBAROLI D., MORELLI L., RITTER M., ROVIRA E.,
SALA P., BERTARINI L., SANVITO S. (1999) - Changes
in sedimentation rates in all Mediterranean
drillsites document basin evolution and support
starved basin condition after early Zanclean
flood. Mem. Soc. Geol. It., 54, 145-159.
D’ALESSANDRO A., MASSARI F., DAVAUD E., GHIBAUDO
G. (2004) - Pliocene-Pleistocene bounded by
subaerial unconformities within foramol ramp
calcarenites and mixed deposits (Salento, SE
Italy). Sedimentary Geology, 166, 89-144.
DE GIORGI C. (1922) - Descrizione geologica ed
idrografica della Provincia di Lecce. Ed. L.
Salomi, Lecce, 263 pp.
DELLE ROSE M. (2006) – Mediterranean Pliocene
events in the Salento geological record.
51
52
Thirty years of Sequence Stratigraphy: Applications, Limits and Prospects - 2 October 2006 - Bari - Italy
STRATIGRAPHIC AND SEDIMENTOLOGICAL INSIGHTS ABOUT THE CAPO SAN
GREGORIO BRECCIAS AND CONGLOMERATES (SOUTH SALENTO)
Marco Delle Rose1 and Fernando Resta2
CNR, IRPI, via G. Amendola 122/i, 70126 Bari
Tel. 080 5929581; Fax 0805929611; e-mail: [email protected]
2
via G. Toma 42, 73100 Lecce
1
The geological literature of the south Salento
peninsula (around Capo S. M. di Leuca) shows a
number of chrono- and lithostratigraphic setting
reconstructions surprisingly high, regarding both
the Cretaceous-Tertiary platform carbonates
and the Quaternary marine-continental clastic
deposits. As an example, the eastern well
exposed coastal cliff has been considered
belonging to: a Paleocene-Oligocene Calcari
di Castro formation (SERVIZIO GEOLOGICO D’ITALIA,
1968); an undifferentiated succession of preNeogene formations (BOSSIO et alii, 1987);
a Oligocene-Miocene clinostratified slope
systems including reef tracts (BOSELLINI et
alii, 1999, 2001). Moreover, the outcropping
carbonate substratum of the west ionian coast
up to the Pesculuse littoral has been referred
entirely to the Cretaceous (SERVIZIO GEOLOGICO
D’ITALIA, 1968) or locally made up by Miocene
formations (BOSSIO et alii, 1987; CIARANFI et alii,
1988). Along this shore tract, the breccias and
conglomerates overlying the above mentioned
platform carbonates at Capo San Gregorio
(fig. 1), have been referred to: weathering
continental slope deposits (SERVIZIO GEOLOGICO
D’ITALIA, 1968); shoreface deposits linked to a
3-4 m a.s.l. paleo-shoreline (COTECCHIA et alii,
1969); a marine conglomeratic lithostratigraphic
unit named Leuca formation (BOSSIO et alii,
1987, 2001).
Preliminary stratigraphic and sedimentological
observations carried out at Capo San Gregorio
allow us to distinguish the main features of
breccias and conglomerates and to delineate
their outcropping extensions, as briefly
summarized. Some units have been observed:
1) weathering continental slope deposits
characterized by a medium-coarse breccia
(clasts of limestones, dolomitic limestones and
calcarenites) within a well cemented reddish
matrix spread all around the area. Frequently
are present well cemented interlayered reddish
hard crusts. The whole deposit is characterized
by terrace shaped morphology; 2) debris-mud
flow deposits showing embricated structures,
wide sorted and rich in bauxite pisolites; they
are usually associated to the aforementioned
slope deposits; 3) well smoothed conglomerates
(mainly limestones and calcarenites content)
within a well cemented yellowish carbonate
matrix, characterized by a wide sorting with
clasts ranging from some centimetres up to
some decimetres; 4) coarse conglomeratic
level at the base of cross-bedding reddish
calcarenites which shows a thickness of about
of 0.5 m; more or less rounded pebbles are
randomly present also within the overlying
calcarenites 5) intraclastic breccia layers
interbedded
within
carbonate
platform
succession; the best outcrop is located in
point number 3 in the attached map, where the
succession is thick about 15 meters.
More considerations must be done regarding
the evidences of the litological features above
described. Here we preliminary approach
some questions. The weathering continental
slope deposits are widespread along the
Salento southwest coast between Pesculuse
and Leuca. Its well cemented reddish matrix
could emphasize continental or transitional
diagenetic processes during paleo-climatic
favourable
conditions,
meanwhile
their
terraced morphologies seems to be undergone
to erosion processes of shoreline retreat.
Moreover, breccias in reddish matrix, containing
terrestrial fossil bones, are described along the
east Salento coast as the result of interglacial
processes (DI STEFANO et alii, 1992).
The well smoothed conglomerates (1 of fig.1)
are evidently shoreface deposits. According to
the literature, they can indicate a Tyrrhenian
high stand (COTECCHIA et alii, 1969; DAI PRA
& HEARTY, 1988). At Pesculuse area (about
5 km far from Capo San Gregorio towards
North-West), D’ALESSANDRO & MASSARI (1997)
have been recognized shoreface limestone
conglomerates, whereas along the present
shoreline, coarse clastic deposits in reddish
matrix can be observed.
Tacking into account that the platform
carbonates of Capo San Gregorio are partially
referred to the pre-evaporitic Messianian
(BOSSIO et alii, 1987; CIARANFI et alii, 1988), a
working hypothesis is to consider the strata
53
Fig. 1 – Some outcrops of Capo San Gregorio breccias and conglomerates managed by GIS. 1, well
smoothed conglomerates; 2, terraced breccia in reddish matrix; 3, intraclastic level within platform
carbonates; A, B and C, Leuca formation according to BOSSIO et alii (1987); A, weathering continental
slope deposits according to SERVIZIO GEOLOGICO D’ITALIA (1968); C, shoreface reddish breccia according
to COTECCHIA et alii (1969).
containing the intraclastic breccia layers as
part of the aforementioned deposits. Following
this suggestion, the intraclastic breccias could
be related to the analogous deposits contained
within a reef complex of the south-east Salento
coast, which is truncated by a erosion surfaces
interpreted as indicator of relative fourth order
sea-level fluctuation (BOSELLINI et alii, 2001).
If the so called Leuca formation can be found at
Capo San Gregorio, it hasn’t the considerable
extensions reported by BOSSIO et alii (1987)
especially along the south-west side of Capo
San Gregorio itself, where are mainly present
both the weathering continental slope deposits
and the intraclastic breccia layers (see 3 and B
in fig. 1). We have also to mention that a detailed
geological mapping of Est of Lecce zone (DELLE
ROSE et alii, 2006), has carried out the presence
of a decimetres breccias underling a centimetres
phosphatized calcirudite in place of some tens
of metres thick “Leuca formation” mapped by
BOSSIO et alii (1999). As a consequence the
aforementioned unit cannot be considered a
formation according to the stratigraphic codes
(NORTH AMERICAN COMMISSION ON STRATIGRAPHIC
NOMENCLATURE, 1983; COMMISSIONE ITALIANA DI
STRATIGRAFIA DELLA S.G.I., 2003).
In conclusion, as suggest by some characteristics
of the Capo San Gregorio breccias and
conglomerates, multidisciplinary analyses
of these deposits can offer opportunities
to understand paleo-environmental and
climatic features of source areas as well as
sedimentation ones.
In order to optimize the management of all
existing and collected geological data, a GIS
data base will be implemented. The main
aim is the availability of a mean able also to
confront different geological interpretations and
to discern among those sites that need further
investigation. Not only maps can be introduced
in the GIS data base but also stratigraphic
54
sections, drill logs and all those not geological
map data geographically linkable (DELLE ROSE
et alii, 2006).
COTECCHIA V., DAI PRA G., MAGRI G. (1969)
– Oscillazioni tirreniane e oloceniche del livello
del mare nel Golfo di Taranto, corredate da
datazioni col metodo del radiocarbonio. Geol.
Appl. Idrogeol., 4, 93-147.
COMMISSIONE ITALIANA DI STRATIGRAFIA DELLA S.G.I.
(2003) – Giuda italiana alla classificazione e alla
terminologia stratigrafica, APAT, quad. s. III, 9.
DAI PRA G., HEARTY P.J. (1988) - I livelli marini
pleistocenici del Golfo di Taranto. Sintesi
geocronologica e tettonica. Mem. Soc. Geol. It.,
41, 637-644.
D’ALESSANDRO A., MASSARI F. (1997) - Pliocene and
Pleistocene depositional environment in the
Pesculuse area (Salento, Italy). Riv. It. Paleont.
Strat., 103, 221-258.
DELLE ROSE M., PAPPAFICO G., RESTA F. (2006) –
Problematiche stratigrafiche e cartografiche del
Pliocene ad est di Lecce. Atti 83a Riun. Est. Soc.
Geol. It., Chieti, 12-16 settembre 2006, 117-120.
DI STEFANO G., PETRONIO C., SARDELLA R., SAVELLONI
V., SQUAZZINI E. (1992) – Nuove segnalazioni di
brecce ossifere nella costa fra Castro Marina e
Otranto (Lecce). Il Quaternario, 5, 3-10.
NORTH AMERICAN COMMISSION ON STRATIGRAPHIC
NOMENCLATURE (1983) – North American
Commision on Stratigraphic nomenclature. The
American Association of Petroleum Bulletin, 67,
841-875.
SERVIZIO GEOLOGICO D’ITALIA (1968) – Carta geologica
d’Italia a scala 1:100.000, Foglio 223 – Santa
Maria di Leuca, II ed., Roma.
References
BOSELLINI A., BOSELLINI F.R., COLALONGO M.L., PARENTE
M., RUSSO A., VESCOGNI A. (1999) - Stratigraphic
architecture of the Salento coast from Capo
d’Otranto to S. Maria di Leuca (Apulia, southern
Italy). Riv. It. Paleont. Strat., 105, 397-416.
BOSELLINI F.R., RUSSOA., VESCOGNIA. (2001) - Messinian
reef-building assemblages of the Salento
Peninsula (southern Italy): palaeobathymetric and
palaeoclimatic significance. Palaeogeography,
Palaeoclimatology, Palaeoecology, 175, 7-26.
BOSSIO A., MAZZEI R., MONTEFORTI B., SALVATORINI G.
(1987) - Evoluzione paleogeografica dell’area di
Leuca nel contesto della dinamica Mediterranea.
Quad. Ric. Cent. St. Geot. Ing., 11, 31-54.
BOSSIO A., FORESI L.M., MARGIOTTA S., MAZZEI
R., MONTEFORTI B., SALVATORINI G. (1999)
– Carta geologica del settore nord orientale della
provincia di Lecce, scala 1:25.000; settori 7, 8,
10 scala 1:10.000, Università di Siena.
BOSSIO A., MAZZEI R., MONTEFORTI B., SALVATORINI G.
(2001) - Note illustrative alla carta geologica
della zona di S. Maria di Leuca. Soc. Tosc. Sc.
Nat., 107, 97-163.
CIARANFI N., PIERI P., RICCHETTI G. (1988) - Note
alla carta geologica delle Murge e del Salento
(Puglia centromeridionale), Mem. Soc. Geol. It.,
41, 449-460.
55
56
Thirty years of Sequence Stratigraphy: Applications, Limits and Prospects - 2 October 2006 - Bari - Italy
STRATIGRAPHIC ARCHITECTURE AND DEEP HYDROSTRATIGRAPHY IN THE
PLIOCENE TO HOLOCENE DEPOSITS OF THE WESTERN PO PLAIN
Andrea Irace1*, Natalicchio Marcello1, Clemente Paolo1, Trenkwalder Stefania1, Mosca
Pietro1, Polino Riccardo1 , Violanti Donata1,2 and De Luca Domenico Antonio1.
1
C.N.R., Istituto di Geoscienze e Georisorse, Sezione di Torino,
Via Valperga Caluso 35, 10125 Torino
*corresponding author; e-mail: [email protected]
2
Università di Torino, Dipartimento di Scienze della Terra,
Via Valperga Caluso 35, 10125 Torino
Introduction
The Western Po Plain represents the most
important and large fresh-water reserve of the
Piemonte region. This area is characterized
by km-scale accumulations of Pliocene to
Holocene deposits in two basins, namely the
Savigliano (SB) and the Alessandria (AB)
basins, separated by the interposed Asti
region of reduced thicknesses. The Savigliano
and Alessandria basins are bounded by the
Monferrato and Torino Hill to the north, the
Tertiary Piedmont Basin to the south and the
Alps to the west and SW (fig. 1).
Until now, the first 200 m of the Pliocene
to Holocene deposits were largely used for
hydrogeologic purposes giving a rich lithostratigraphic dataset. By the contrast, data
about the stratigraphic and hydrostratigraphic
settings beneath this depth, reached only by a
few exploratory wells, are quite fragmentary.
This contribution is the result of a still ongoing
project, financially supported by the CIPE, that
has been assigned by the Regione Piemonte to
the CNR-IGG (Sez. Torino) and Earth Sciences
Department of Torino University. The aim of
this project is to reconstruct a regional geologic
model in order to define the geometry of deep
fresh-water acquifers within the buried Pliocene
to Holocene successions of the Piemonte
region.
Stratigraphic Architecture
The reconstruction of the 3D-stratigraphic
architecture and facies distribution of the basin
fill represents the first step to define the presence
of aquifers in order to propose a hydrogeologic
model. The dataset used in this work consists of
new sedimentological and micropaleontological
data for the outcropping Neogene to Quaternary
successions, exploratory well-logs (AGIP, 1972;
1994) and available seismic reflection lines
(MOSCA, 2006). The analysis carried out for the
scope of this work comprises also the Upper
Messinian deposits in order to better define the
pre-Pliocene physiographic framework of the
basin areas.
In the SB and AB, six stratigraphic units have
been widespread recognized, bounded by
unconformities and correlative conformities.
The considered dataset allowed to identify
major depositional environments within the
identified units.
The Late Messinian unit (LM), that is the
Fig. 1 - Geological sketch map of the Western Po Plain. (after CNR, 1983)
57
lowermost unit here discussed, is floored by an
erosional surface associated with an angular
unconformity that cuts primary Messinian
evaporites in marginal settings. The LM consists
of resedimented evaporites (both chaotic and
stratified) and sand-rich successions that
reach a maximum thickness of about 600 m in
depocenters located in the SB and AB.
The Early Pliocene unit (eP1) consists of
marine facies correlated with outcrops of
clay-rich successions. It marks the MiocenePliocene boundary, that in previous marginal
settings corresponds to a sharp transgressive
transition to open-marine environments. Major
accumulations are on the order of 500-600 m in
depocenters roughly located in the central part
of the SB and AB.
The Early to Middle Pliocene unit (eP2) is
characterized by the development of prograding
basin-margin systems (seismically imaged by
clinoforms wedges) from the southern and
south-western sectors. This unit marks the
beginning of a regional regressive evolution.
Principal depocenters (corresponding to the
previous ones) accommodated thickness on
the order of 500-600 m.
The two overlying units, labelled as Late
Pliocene (LP) and Pleistocene p.p. (Ple),
are mainly represented by marginal-marine
and continental deposits respectively. These
units are separated in marginal settings by
an angular unconformity, associated to a
temporal gap spanning from Late Pliocene to
Early Pleistocene (CARRARO, 1996). Their total
thickness is about 900 m in depocenters stably
fixed in the SB and AB. In the depocenter of AB,
well-data suggest marine condition during the
Pleistocene p.p..
Fig. 2 – Block diagram of a sample area showing: the recognized stratigraphic units (fig. 2a), the
gross lateral and vertical arrangement of different depositional systems (fig. 2b), the 3D distribution
of principal lithologies (fig. 2c) and the spatial distributions of the aquifer complexes A to F (fig. 2d).
Location of the sample area is shown in fig. 1.
58
The Pleistocene p.p. to Holocene unit (PH)
widespread consists of continental deposits,
<100m thick. Along the Alpine margin this
unit is typically represented by alluvial fan
successions, progressively evolving into alluvial
plain environments toward the east.
The deposition of foredescribed units
underwent in a regional scenario dominated
since the Miocene by the development of northverging thrust systems (Mosca, 2006).
it physically crosses the different stratigraphic
units.
Conclusions
As a major result of present study, the
distribution of the identified acquifer complexes
is independent from the reconstructed
chronostratigraphic framework. In addition, the
position of the fresh-saltwater interface is largely
influenced by the kind and the distribution of
the depositional environments while it is totally
independent by the depositional ages of the
stratigraphic units.
Hydrostratigraphy
The recognized stratigraphic units (fig. 2a),
the gross lateral and vertical arrangement of
different depositional systems (fig. 2b) and
the 3D distribution of principal lithologies
(fig. 2c) have allowed to identify a number of
different aquifer complexes and their spatial
distributions (fig. 2d). Each complex, adopted
as basic hydrogeologic unit, groups more
aquifers with similar sedimentological features,
i.e. homogeneous facies association, referable
to analogous but diachronus depositional
environments.
Attention has been focused on the
distribution of fresh-saltwater interface and
its relationships with the hydrogeologic
complexes. This interface, that represents the
lower limit of freshwater reserves, has been
traced throughout both the AB and SB where
References
AGIP (1972) – Acque dolci sotterranee. Inventario
dei dati raccolti dall’Agip durante la ricerca di
idrocarburi in Italia, 914 pp.
AGIP (1994) – Acque dolci sotterranee. Inventario
dei dati raccolti dall’Agip durante la ricerca di
idrocarburi in Italia, 515 pp.
CARRARO F. (1996) - Revisione del Villafranchiano
nell’area-tipo di Villafranca d’Asti. Il Quaternario,
9 (1), 119 pp.
MOSCA P. (2006) – Neogene basin evolution in
the Western Po Plain (NW Italy). Insights from
seismic interpretation, subsidence analysis and
low temperature (U-Th)/He thermochronology.
Ph.D. Thesis. Vrije Universiteit, Amsterdam, The
Netherlands, 190 pp.
59
60
Thirty years of Sequence Stratigraphy: Applications, Limits and Prospects - 2 October 2006 - Bari - Italy
SEQUENCE STRATIGRAPHY OF THE POTENZA BASIN PLIOCENE COARSEGRAINED DELTAS (SOUTHERN ITALY): RECOGNITION OF MEDIUM- AND HIGHFREQUENCY RELATIVE SEA-LEVEL OSCILLATIONS DURING THE SEDIMENTATION
Sergio Longhitano
University of Basilicata, Department of Geological Sciences,
Campus di Macchia Romana, 85100, Potenza, Italy. E-mail: [email protected]
Introduction
This study deals with the depositional
sequences that occur within the uppermost
part of the Pliocene Potenza Basin (P.B.) fill,
a thrust-top depression located in the central
sector of the Lucanian Apennines, southern
Italy (Fig. 1, inset).
The location of the study corresponds with a
natural cliff (Ciciniello section) exposes along
the southern margin of the P.B.
The P.B. sedimentary fill is composed by two
lower-middle Pliocene units, known as Altavilla
and Ariano Units (Di Nocera et alii,1988;
Lazzari et alii, 1988). The Altavilla Unit consists
of lower Pliocene conglomerates and sands,
forming the northern part of the P.B., while
the middle Pliocene Ariano Unit forms the
southernmost deposits, mainly composed
by transgressive marine, shallow-water and
clinostratified conglomerates and sandstones,
passing upwards to shelf mudstones (Vezzani,
1967; D’Argenio et Alii, 1973).
The lowermost part of the Ariano Unit is
represented by a series of north-easterly
dipping clastic, coarse-grained wedges (40-50
m thick), unconformably lying on the deformed
pre- and lower-Pliocene bedrock (Fig. 1).
The succession shows an overall shallowing
trend from slope clays to shallow-marine and
non-marine deposits comprising two major
sequences (P1 and P2). Coarse-grained delta
systems represent a volumetric significant
part of the P.B. sedimentary fill (Longhitano &
Colella, 2004).
Vertical trends in the architecture of the
deltaic succession show changes in the
stratal stacking pattern related to the forcing
of different amplitudes of relative sea-level
changes. Overall, the middle-Pliocene coarsegrained deltas of the southern P.B. sedimentary
fill record a medium-term sea-level oscillations,
punctuated by repeated, high-frequency
eustatic sea-level changes.
Description
and
interpretation
of
sedimentary facies associations
The facies associations occurring within the
P1 and P2 sequences are representative
of inner-shelf to subaerial settings and are
distinguished mainly on the basis of physical
and biogenic sedimentary structures, grain size
and palaeontological content.
Facies association A: this facies association
comprises mudstones cropping out in small
scarps and represents the lowermost levels of
the P1 and P2 sequences. It consists primarily of
thoroughly bioturbated and massive grey clays
and silty clays with sparse shell fragments,
Fig. 1. Schematic
geological map of the
Potenza basin (see the
inset for regional position)
and location of the study
Ciciniello section. The
white arrows indicate the
progradation direction
of the main sedimentary
systems.
61
variably interbedded with thin, fine to very
fine sands. Sharp-based fine sand layers are
up to about 10 cm thick and normally graded
and contain relict horizontal planar lamination.
This facies association records deposition in
an open marine setting, below storm wave
base. Sand layers reflect the waning flow
deposits of storm-generated currents, while the
clayey portion resulted from fallout deposition
of suspended fine material as well as stormemplaced sediment (Fig. 2A).
Facies association B: this facies association
lies above the previous facies association, and
is characterized by fine to medium grained sand
beds, interbedded with massive, bioturbated
and fossiliferous silty clays. Sand beds are
characterized by a gently undulating low-angle
cross-lamination with the convex-upward part
the hummock and the concave-downward part
the swale. They are up to 50 cm thick, have
sharp bases and may pass upward into wave
rippled silty to very fine-grained silty sands (Fig.
2A).
This cross-stratification suggests deposition
during waning oscillatory flows and periodic
storm events. This facies association
represents the deposition of sediment fallout
occurring between fair-weather and stormwave base and reflects accumulation in an
offshore-transition environment under the
action of sporadic storms.
Facies association C: this facies association
consists mainly of thoroughly amalgamated
and intensely bioturbated fine- to mediumgrained sandstone with thin (up to 20 cm)
horizontal and discontinuous pebbly layers
composed of few centimeters of well-rounded
pebbles and granules, and sub-horizontal
erosional surfaces. Wave-ripple laminated
sands and rare lenticular gravel layers with
pronounced concave-up erosional base also
occur. Individual lenticular layers are 2-3 m
wide, up to 0.5 m in depth and have longshoreoriented axis (Fig. 2B).
This sandy facies characterized by swale
cross-stratification and hummocks indicates
a lower shoreface zone, characterized by
fair-weather waves reworking the tops of the
Fig. 2. Outcrop photographs showing the sedimentological characteristics of facies and facies
assemblages within the studied units. (A) Mudstones and siltsones of the facies association A and B.
The succession evolves upward to the sandstones of facies association C. (B) Swaley cross-stratified
sandstone in the lower shoreface facies association. (C) Clinostratified gravel/sand couplet of beds
of the P2 sequence downlapping onto the transgressive surface, bounding the top of the lower P1
sequence. (D) Detail of the previous photograph.
62
63
Fig. 3. (A) Photomosaic of the Ciciniello section. (B) Interpretative linedrawing. The deltaic succession of the lower P1 depositional sequence develops
according to alternating increase/decrease of thickness and aggradation/progradation of the clinoforms. Every progradational stage (high-frequency sea-level
falls) are marked by the formation of a basal, concave-up erosive surface (lower-rank SBs). The upper P2 sequence records a subsequent medium-frequency
rise of the sea level. (C) The P1 records the transition between the highstand and subsequent fall of the relative sea-level. The lowstand systems tract is NNE
out of this section (on the right). The P2 records the younger sea-level rise and consequent highstand.
storm deposits and formed wave ripples. The
coarser beds indicate the occurrence of storm
events, without the preservation of fairweather
deposits, whereas the lenticular gravel beds
record the infilling of longshore troughs.
Facies Association D: clinostratified sand and
gravel layers are the dominant feature of this
facies association. Each gravel-sand couplet
tends to wedge-out landward, decreasing the
dip seaward and forming bottomset geometries.
Gravel layers are usually sharp based, up to
few decimeters thick, and usually composed
of well rounded clasts of different size (Fig.
2C). This facies association records deposition
along a wave-reworked delta slope, where the
flux of sediment falls under the effect of gravity
but partially reworked by the wave action (Fig.
2D).
Facies association E: the coarse-grained
clinoforms pertaining to the previous facies
association are truncated at the top, throughout
a erosive surface bounding the base of
horizontal beds of sandy conglomerates,
characterized by erosive small channels
and overbank sandy deposits. This facies
association represents the topset part of a
deltaic sequence. It results rarely preserved in
all the sections measured and is absent in the
vast majority of the cases.
D vertical-stacked facies associations, and is
base-bounded by a transgressive condensed
succession, slightly onlapping onto the top of
the P1, and marking the base of a new highstand
NNE-prograding deltaic system (Fig. 3B).
Within the P1 sequence, depositional
architecture and facies arrangement allow to
discriminate high-frequency sea-level changes
during sedimentation. Along the Ciciniello
section, the clinoforms of the P1 sequence
occur prominently and show cyclical variation
in the foresets dipping angle (the inclination
ranges from 20° to 35° to 19-20° again). This
geometric repetition occur along the prograding
direction and realizes within a few tens of
metres (Fig. 3C).
Simultaneously, the variations in the
clinostratification
dip
corresponds
with
alternating increases and decreases of
clinoforms thickness, that realizes throughout
concave-up, erosive basal surfaces within the
pre-Pliocene muddy bedrock.
This
vertical-longitudinal
stratigraphic
arrangement suggests alternating stage of
aggradation and progradation of the deltaic
system, reflecting high-frequency sea-level
oscillations. The unpreservation of the topsets
is due to the sub-aerial exposure during the
stages of sea-level fall. Contemporaneously, the
system are constrained to develop downwards,
eroding the substrate and creating concave-up
lower surfaces of progradation (Fig. 3B). These
surfaces represent lower-rank SBs, separating
high-frequency deltaic minor sequences.
Sequence stratigraphy: from mediumto
high-frequency
relative
sea-level
oscillations.
In order to synthesize a framework of the
medium-frequency sequential arrangement of
the P.B. southern succession, is here presented
the interpretation of a single geological profile,
localized along the south-eastern side of the
Ciciniello hill (Fig. 3A).
The well exposed stratigraphic succession
cropping out along this natural cliff comprises
a series of vertical stacked, small deltaic
sequences, prograding toward NNE (basin
depocenter) onto a erosive surface (SB1).
The two depositional sequences (P1 and P2)
are formed by HST+FSST and TST+HST
respectively and are separated by a younger
transgressive surface (SB2) that abruptly
divides the deepest from the shallowest facies
associations. The first lower sequence P1 is
formed by highstand-to-falling stage NNEprograding, coarse-grained deltas. The top of
the P1 sequence is bounded by a surface of
relative sea-level fall, that moves basinward
the depositional system to form a new lowstand
deltaic system, pertaining to the younger
P2 depositional sequence (out of the study
section). The P2 is characterized by the A-B-C-
References
D’Argenio, B., Pescatore, T. e Scandone, P. (1973).
Schema geologico dell’Appennino meridionale
(Campania e Lucania). Atti del convegno
“Moderne vedute sulla geologia dell’Appennino.
Accademia Nazionale dei Lincei, 183, 49–72.
Di Nocera, S., Lazzari, S., Pescatore, T., Russo,
B., Senatore, M.R. e Tramutoli, M. (1988). Note
illustrative della carta geologica dell’Alta valle
del Basento (Appennino Lucano, Italia). Atti
del convegno Ambiente Fisico: uso e tutela del
territorio di Potenza. Regione Basilicata.
Lazzari, S., Pescatore, T., Russo, B., Senatore,
M.R., Tramutoli, M. (1988) Bacini pliocenici
nella zona di Potenza (Appennino meridionale).
Memorie della Società Geologica Italiana, 41,
363-371.
Longhitano S., Colella A., 2004. Gilbert-type deltas in
the thrust-top Potenza Basin (Pliocene, southern
Apennines). Atti della Riunione GeoSed “La
geologia del sedimentario nella ricerca di base
e nelle sue applicazioni. Roma 22-28 settembre
2004.
Vezzani, L. (1967). Il bacino plio-pleistocenico di S.
Arcangelo (Lucania). Atti dell’Accademia Gioenia
Scienze Naturali, Catania, VI, 18, 207–227.
64
Thirty years of Sequence Stratigraphy: Applications, Limits and Prospects - 2 October 2006 - Bari - Italy
CONTINENTAL SEQUENCES IN SAHARA DOMINATED BY CLIMATIC CHANGES
Gian Gabriele Ori
International Research School of Planetary Sciences, Universita’ d’Annunzio,
Viale Pindaro 62, 40135 Pescara
Adrar des Iforhas and Air. The upper part of
this southwards flowing system is now dry
and correspond to the paleovalley of Azaouak
and adjacent paleovalleys. The Sahara during
wetter climatic periods was covered by lakes
and swamps in the deepest parts of the
inland basins. These lakes were supplied by
exotic rivers forming deltas at their mouths.
These rivers formed paleovalleys that are now
inactive or occupied by ephemeral streams
with episodic floods. Terminal fans replace
the deltaic systems. Aeolian deposits and ergs
have been generated during the driest period
and are interbedded with fluvial and lacustrine
deposits. The interactions between these
deposits are dominated by the changes of
climate and form sequences that are bounded
by erosional or not-depositional surfaces.
River systems in desert regions are, basically,
of two types: ephemeral streams and exotic (or
allogenic) rivers. In contrast to the ephemeral
streams, exotic rivers are perennial and survive
hydrological crisis. Unique features of this type
of rivers are the inland deltas where they form
intricate patterns of small channels and lose a
large part of the water. Exotic rivers flowed in
Sahara during wet climatic periods and they
left a number of dry streams and paleovalleys.
Most of these ancient courses are at present
time ephemeral streams or they are totally
inactive. During the wet climatic periods,
the Niger river was split in two unconnected
reaches: the upper reach was flowing to the
north forming a large inland delta in the area
of Azouad (north of Timbuktu), whereas the
distal reach was flowing to the south from the
65
66
Thirty years of Sequence Stratigraphy: Applications, Limits and Prospects - 2 October 2006 - Bari - Italy
ARCHITETTURA DEPOSIZIONALE DEGLI ACCUMULI A MINERALI PESANTI
(PLACERS): ESEMPIO NELL’ORDOVICIANO DELLA SARDEGNA E DELLA
BRETAGNA
STACKING PATTERN OF HEAVY MINERALS ENRICHMENT (PLACERS):EXAMPLE OF
THE ORDOVICIAN OF SARDINIA AND BRITTANY
Marco Pistis1, Alfredo Loi2, Francesco Leone2, Egidia Melis3, Anna Maria Caredda2
and Marie-Pierre Dabard4
Via S.Avendrace, 209, 09122 Cagliari, Italy; E-mail: [email protected]
Dip. di Scienze della Terra - Università di Cagliari - Via Trentino, 51, 09127 Cagliari, Italy
3
Progemisa - Agenzia Governativa Regionale - via L. Contivecchi 7, 09122 Cagliari, Italy
4
Géosciences UPR4661 - Campus de Beaulieu, 35042 Rennes Cedex, France
1
2
Lo scopo di questo lavoro é di fornire un modello
predittivo
dell’architettura
deposizionale
degli accumuli a placers nelle sequenze di
piattaforma terrigena, ad altissima e media
frequenza.
Gli accumuli di minerali pesanti nelle piattaforme
terrigene si mettono in posto in ambienti di
shoreface e offshore superiore a causa di eventi
idrodinamici ad alta energia come le tempeste
(CLIFTON, 1969; FAURE, 1978; KOMAR & WANG,
1984; MACDONALD & ROZENDAAL, 1995; DE MEIJER,
1998). La composizione dei depositi terrigeni
e la relativa abbondanza di minerali pesanti
dipendono sia dalle condizioni autocicliche sia
dai fattori allociclici, come variazioni del flusso
terrigeno, velocità di subsidenza ed eustatismo
in quanto l’analisi stratigrafica di una stessa
sezione geologica mostra che identiche facies
di shoreface e offshore superiore possono
contenere valori da nulli a molto elevati di
minerali pesanti. Inoltre, fattori locali come
la composizione dell’area sorgente e le
condizioni paleoclimatiche possono controllare
la presenza e l’abbondanza di tali fasi minerali
lungo il profilo di deposito. Per poter proporre
un modello stratigrafico indipendente dalle
condizioni locali, sono state prese in esame
tre formazioni geologiche di età e posizione
paleogeografica differenti: le Formazioni del
Grès Armoricain e di Postolonnec (Fig. 1,
2) dell’ Ordoviciano inf-medio (CHAUVEL & LE
CORRE, 1974; MÉLOU & PLUSQUELLEC, 1979) nella
Penisola di Crozon in Bretagna (NW Francia) e
la Formazione di Punta Serpeddì (Fig. 3) dell’
Ordoviciano sup. (Barca & Di Gregorio, 1979;
1979; LOI et alii, 1992 ; LOI, 1993) del Sarrabus
in Sardegna (Italia).
Lo studio petrografico (supportato da analisi
diffrattometriche ai raggi x e microanalisi al
S.E.M, in base alle quali è stata effettuata
l’identificazione delle fasi mineralogiche
presenti ed una valutazione semiquantitativa
delle stesse), ha mostrato che, sia in Sardegna
che in Bretagna, i minerali pesanti sono
rappresentati da titaniferi (rutilo, pseudorutilo,
anatasio,ecc), zirconi e monaziti. In identiche
facies sono state riscontrate concentrazioni
variabili da 0 a 40% di minerali pesanti totali
(titaniferi=22%; zirconi=14%; monaziti=3%).
Misure di radioattività spontanea sono state
effettuate in maniera pressoché continua lungo
tutte le sezioni tramite il contatore Geiger
“RR66 DV-46/49 Radiometer” e lo spettrometro
portatile “Exploranium GR-320 enviSpec”.
Quest’ultimo è un contatore di impulsi a
scintillazione fornito di uno standard al 137Cesio
che permette di discriminare dallo spettro della
radiazione totale i picchi del 40K, 238U, 232Th. I dati
radiometrici sono stati riportati lungo le sezioni
stratigrafiche in forma di diagrafie, le quali
mostrano valori di radioattività relativamente
alti in corrispondenza degli accumuli a minerali
pesanti, mentre dove questi sono assenti
si rilevano valori prossimi a quelli del fondo
naturale.
Lo studio delle sezioni e delle diagrafie ha
permesso di quantificare in maniera agevole
la distribuzione verticale dei minerali pesanti e
distinguere 4 facies radiometriche corrispondenti
ad altrettante facies sedimentarie (Fig. 1) :
-FACIES 1. (ETEROLITICA E BANCHI
ARENACEI A BASSA RADIOATTIVITÀ)
Questa facies di gamma ray è caratterizzata
da valori in cpm totali relativamente bassi
(2.000-3.000 cpm); inoltre U e Th si
mantengono bassi (50-200 cpm), mentre
il K varia da valori minimi di 250 cpm, nei
banchi arenacei, a valori massimi di 600
cpm in corrispondenza dei livelli argillosi.
67
Fig. 1- Sezione stratigrafica di “Le Corrèjou” (passaggio tra la Formazione del Grès Armoricain e la
Formazione di Postolonnec nella Presqu’ île de Crozon in Bretagna). Interpretazione sequenziale,
diagrafia Gamma Ray in “counts per minute” (cpm) e “Röentgen all’ ora” (R/h), e concentrazioni di
minerali pesanti totali (M.P).
La presenza di minerali pesanti è scarsa,
(0.5%).
valori in cpm totali medi (4.000-6.000 cpm)
e valori bassi di U e Th (100-300 cpm). Il
K assume in questa facies i valori massimi
(900-1.300 cpm).
-FACIES
2.
(ARENARIE AD ALTA
RADIOATTIVITÀ). Questa facies presenta
valori alti in cpm totali (sino a 88.000 cpm).
Il Th e l’U assumono valori elevati con
massimi rispettivamente di 9.600 e 6000
cpm. I minerali pesanti sono particolarmente
abbondanti con concentrazioni massime
del 40%.
Lo studio sequenziale basato sull’ analisi di
facies ha permesso di costruire una curva di
impilamento verticale di sequenze genetiche
(Homewood et alii, 1992). Questa curva
mostra l’evoluzione verticale delle facies in
un diagramma con duplice tendenza: verso il
polo marino e verso quello continentale. Alla
scala delle sequenze genetiche questa curva
può essere considerata come direttamente
influenzata dall’eustatismo.
-FACIES 3. (ETEROLITICO A MEDIA
RADIOATTIVITÀ).
Questa
facies
è
caratterizzata da valori in cpm totali medi
(4.000-5.000 cpm) e da valori bassi di U e
Th (100-200 cpm). Il K segue l’andamento
della radioattività totale assumendo i valori
massimi (1.000 cpm) in corrispondenza
dei livelli argillosi. La presenza di minerali
pesanti è molto scarsa o nulla.
Lo studio delle diagrafie Gamma Ray, associato
all’analisi sequenziale, ha messo in evidenza
che le più importanti concentrazioni a minerali
pesanti si mettono in posto durante i periodi
di massima accelerazione di risalita eustatica
delle sequenze di media frequenza (3° Ordine?)
e in coincidenza di ambienti deposizionali di
-FACIES
4.
(ARGILLE
A
MEDIA
RADIOATTIVITÀ). Questa facies possiede
68
69
Fig. 2- Rapporti stratigrafici degli orizzonti a minerali
pesanti e correlazione su basi biostratigrafiche e
sequenziali delle sezioni musurate nella Presqu’ île
de Crozon in Bretagna.
alta energia (Fig. 2, 3).
Questa architettura deposizionale può essere
spiegata tramite la partizione volumetrica degli
ambienti sedimentari (CROSS & LESSENGER,
1998). Nelle fasi di risalita eustatica il flusso
sedimentario proveniente dal continente
si
riduce
fortemente,
producendo
la
retrogradazione dei corpi sedimentari litorali.
Inoltre durante una risalita eustatica a
media frequenza lo stock sedimentario della
zona sottoposta alla dinamica litorale viene
rimaneggiato ripetutamente dalle continue
oscillazioni del livello marino a più alta
frequenza.
Fig. 3- Sezione di “Sa Murta” (Formazione di Punta Serpeddì in Sardegna).
70
Contrariamente, nei periodi di discesa
eustatica il flusso sedimentario è abbondante,
producendo forte progradazione e diluizione
continua dello stock sedimentario negli
ambienti prossimali.
I depositi studiati possono essere perciò
considerati
come
l’espressione
della
condensazione in ambienti di altissima
energia prodotta dalla variazione del tasso
di sedimentazione durante i periodi di
accelerazione di risalita eustatica.
FAURE P.-P. (1978) - Les Grès à rutile et zircon
du Massif Armoricaine. Thèse de Doctorat,
Paris.293 p Inedita.
HOMEWOOD P., GUILLOCHEAU F., ESCHARD R. & CROSS
T. A. (1992) - Corrélations haute résolution et
stratigraphie génétique: une démarche intégrée.
Bulletin du Centre de Recherche ExplorationProduction Elf-Aquitaine, 16: 357-381, Pau.
KOMAR P. D. & WANG C. (1984) - Processes of
selective grain transport and the formation of
placers on beaches. J. Geol., 92: 637-655,
Chicago.
LOI A. (1993) - Sedimentological-Petrographical
study and paleogeographical approach of
the Upper Ordovician of the central southern
Sardinia. European Journal of Mineralogy
“Plinius”, 9: 81-86, Stuttgart.
LOI A., BARCA S., CHAUVEL J. J., DABARD M. P. &
LEONE F. (1992 a) - Analyse de la sédimentation
post-phase sarde: les dépôts initiaux à placers
du SE de la Sardaigne. C. R. Acad. Sci., 315(2):
1357-1364, Paris.
MACDONALD W. G. & ROZENDAAL A. (1995) - The
Geelwal Karoo Heavy mineral deposit: a modern
day beach placer. Journal of African Earth
Sciences, 21(1): 187-200.
MÉLOU M. & PLUSQUELLEC Y. (1979) - Ordovicien de
la presqu’ île de Crozon. Les faciés mèridionaux
et septentrionaux. In: Babin et Courtessole.
Le Paleozoique du Massif Armoricain et de
la Montagne Noire. Bulletin de la Societé
Géologique et Minéralogique de Bretagne,
11(C): 99-102, Rennes.
Opere citate
BARCA S. & DI GREGORIO F. (1979) - La successione
ordoviciano-siluriana inferiore nel Sarrabus
(Sardegna sud orientale. Mem. Soc. Geol. It.,
20:189-202, Roma.
CHAUVEL J. J. & LE CORRE C. (1974) - Notice
explicative de la Carte Gèologique de France.
CLIFTON H. E. (1969) - Beach lamination: nature and
origin. Mar. Geol., 7: 553-559, Amsterdam.
CROSS T. A. & LESSENGER M. A. (1998) - Sediment
volume partitioning: rationale for stratigraphic
model evaluation and high-resolution stratigraphic
correlation, In: Gradstein, F. M.; Sandvuk, K. O.
& Milton, N. J. (Eds): Sequence stratigraphy
concepts and applications, Norvegian Petroleum
Society, S. P., 8:171-195.
DE MEIJER R. J. (1998) - Heavy minerals: from
‚Edelstein‘ to Einstein. Journal of Geochemical
Exploration, 62: 81-103, Amsterdam.
71
72
Thirty years of Sequence Stratigraphy: Applications, Limits and Prospects - 2 October 2006 - Bari - Italy
THE UPPER JURASSIC-LOWER CRETACEOUS CARBONATE PLATFORM
SUCCESSION OF THE WESTERN GARGANO PROMONTORY: DESCRIPTION
AND HIERARCHICAL ORGANIZATION OF HIGH-FREQUENCY DEPOSITIONAL
SEQUENCES
Luigi Spalluto
Dipartimento di Geologia e Geofisica. Università di Bari.
E-mail: [email protected]
Introduction
The sedimentary record of carbonate platform
development is represented by well-stratified
successions referred to lagoonal, intertidal and
supratidal depositional environments usually
ranging from normal-marine to hypersaline
or fresh waters. Carbonate lithofacies are
usually organized in small scale depositional
cycles, commonly correponding to an
individual bed, showing a well-recognizable
shallowing-upward tendency (James, 1984).
This latter is marked by the gradual evolution,
from bottom to top of each cycle, by subtidal,
intertidal and supratidal limestones forming
the world-wide known peritidal cycle. In spite
of this, many peritidal cycles diverge from
the basic model and show a more articulated
lithofacies organization with either deepeningup or shallowing-up trends (Strasser, 1994).
In addition, small scale cycles record and form
part of larger cycles showing transgressive
and regressive trends of lithofacies evolution
(Goodwin & Anderson, 1985). According to
the original definition of depositional sequence
stated by Vail et al. (1977) both elementary and
larger cycles may be assimilated to sequences
and their evolution and stacking pattern in the
sedimentary record may be described in terms
of sequence stratigraphy (Strasser, 1994;
D’Argenio et al., 1997; 1999; Strasser et al.,
1999). The hierarchical stacking of different
orders of sequences is commonly related to
climatically induced sea-level changes in the
Milankovitch frequency band (see D’Argenio et
al., 2004 and reference therein).
This study aims to describe different type
of elementary sequences occurring in the
Upper Jurassic-Lower Cretaceous succession
cropping out in the western part of the Gargano
Promontory. In addition a detailed stratigraphic
study of a nicely exposed section is reported
in order to highlight the hierarchical stacking
pattern of different orders of depositional
sequences.
Description of lithofacies assemblages
in small-scale cycles and hierarchical
organization of depositional sequences
Facies analysis allowed to distinguish in the
whole Upper Jurassic-Lower Cretaceous
platform succession cropping out in the
western part of the Gargano Promontory
the following four main types of small-scale
depositional sequences usually corresponding
to an individual bed:
a) Subtidal sequence (fig. 1A): This type of
sequence record only normal-marine subtidal
lithofacies without evidence of subaerial
exposure or early diagenetic features
superimposed on subtidal limestones. From
bottom to top bioclastic floatstones/rudstones
mostly made up of ostreids and requienids
debris gradually pass to bioturbated biopeloidal
wackestones/packstones
made
up
of
foraminifers and oncoids.
b) High energy shoal sequence (fig. 1B): this type
of sequence record mostly subtidal biocalstic
floatstones/rudstones made up of requienids,
gastropods and requienids gradually passing to
laminated biopeloidal packstones/grainstones
rich in Porostromata and to laminated oolitic
grainstones showing fenestral fabric and early
meteoric vadose cements (either gravitative or
meniscus ones) formed in periodally exposed
shoal environments.
c) Low-energy peritidal sequence (fig. 1C): this
type of sequence corresponds to the classic
peritidal cycle and, from bottom to top, shows
subtidal biopeloidal and oncoidal wackestones/
packstones gradually passing to intertidal
planar and/or wavy stromatolites. Desiccation
features (mud cracks) and early meteoric
vadose features are superimposed on intertidal
limestones.
d) Diagenetic peritidal sequence (fig. 1D): this
type of sequence show a deepening upward
tendency in lithofacies as suggested by the
gradual change from intertidal limestones to
subtidal ones analogues to those described
73
for the previous sequences. The top of subtidal
limestones is cutted by an erosive surface
forming decimetre-sized pockets filled by
residual greenish clays deposited in supratidal
environments.
The detailed stratigraphic study of a section
(Borgo Celano quarry) showed that: a)
diagenetic sequences are not randomly stacked
in the succession and usually repeat after a
discrete rock thickness (fig. 2); b) changes
in bed thickness usually reflect changes in
lithofacies assemblages (thicker beds contain
relatively deeper lithofacies and viceversa); c)
lithofacies stacking patterns allow to recognize
larger transgressive and regressive trends
characterizing system tracts of lower order
sequences.
More in detail, according to the previous
observations, the following sequences have
been recognized (fig. 3): 27 small-scale
sequences, 8 bundles formed by a variable
number (from 2 to 5) of small-scale sequences
and 3 superbundles (only one completely
outcropping from bottom to top) formed by 4
bundles (bundles and superbundles sensu
D’Argenio et al., 1997). Stacking pattern of
lithofacies in bundles and superbundles may be
described in terms of sequence stratigraphy. In
bundles: a) lowstand deposits (LST) correspond
to the residual greenish clay layers which fill
karstic depressions located at the top of smallscale diagenetic sequences; b) transgressive
deposits (TST) correspond to those smallscale sequences which gradually show
deeper lithofacies assemblages upward and a
prevailing early maine cementation (e.g. from
low-energy peritidal small-scale sequences to
fully subtidal ones); c) highstand deposits (HST)
corresponds to those small-scale sequences
which gradually show shallower lithofacies
assemblages upward (e.g. from subtidal
Fig. 1 - Vertical arrangement of lithofacies in
small-scale sequences: A) subtidal sequence;
B) high-energy shoal sequence; C) low-energy
peritidal sequence; D) diagenetic sequence.
Fig. 2 - Borgo Celano quarry: heavy and dashed lines mark sequence boundaries. Bundles and
superbundles boundaries are marked by erosive surfaces (heavy lines) and are covered by residual
greenish clays.
74
sequences to peritidal and diagenetic ones).
The boundary between transgressive and
highstand deposits (maximum flooding surface)
correspond to the most open-water lithofacies
associations usually developed in the thickest
small-scale sequence. In superbundles: a)
lowstand deposits (LST) correspond to thicker
greenish clay layers capping thinner bundles;
b) trangressive deposits (TST) correspond to
groups of bundles showing relatively deeper
lithofacies assembages upward (e.g from
bundles built mainly by peritidal small-scale
sequences to that ones built mainly by subtidal
small-scale sequences); c) highstand deposits
(HST) correspond to groups of bundles showing
relatively shallower lithofacies assemblages
upward (e.g. from bundles built mainly by
subtidal sequences to that ones built mainly
by peritidal or diagenetic ones). The boundary
between transgressive and highstand deposits
(maximum flooding surface) corresponds to
the most open-water lithofacies associations
normally developed in the thickest bundle.
Discussions and conclusions
Small-scale sequences represent the basic
building block of the whole Upper Jurassic-Lower
Cretaceous platform succession cropping out
in the western Gargano Promontory. They are
genetic units that form the smallest identifiable
cycle in facies variation with a regional
meaning. According to many authors their
formation may be explained either by autocyclic
processes (progradation of shallower facies
on deeper ones) or to allocyclic processes
due to tectonics or eustatism. In the studied
section the observed small-scale sequences
are not randomly present in the succession
and they usually repeat after a discrete rock
thickness. This is particularly true for diagenetic
sequences that are capped by residual clay
layers which formed during relatively longer
period of subaerial exposure preceeded by an
important sea-level fall. The stacking pattern
of small-scale sequences mark bigger-scale
trangressive and regressive trends in lithofacies
assemblages which allow to identify two
additional orders of sequences. Moreover, bed
thickness seems to mimic the amount of the
accomodation space on the platform because
usually thicker beds are formed by relatively
deeper lithofacies associations and viceversa.
All these elements suggest that the deposition
of the three orders of sequences was triggered
by allociclic processes which produced relative
Fig. 3 - Log of the Borgo Celano quarry with sequences and systems tracts interpretation. TST:
transgressive deposits. HST: highstand deposits: LST: lowstand deposits.
75
sea level changes of different frequency
and amplitude. The observed hierarchy of
sequences excludes that tectonic triggers
may have directly controlled the production
and deposition of carbonate sediment. On the
contrary, high-frequency eustatic processes
in the Milankovitch frequency band are
interpreted to be the most reliable triggers able
to produce the stacking pattern of different
orders of depositional sequences observed in
the studied section.
– Punctuated aggradational cycles: a general
hypotesis of episodic stratigraphic accumulation.
Journ. Of Geol., 93, 515-533.
JAMES N.P. (1984).- Shallowing-upward sequences
in carbonates. In: Walker R.G. eds. Facies
models. Geological Associationof Canada, St.
Johns, NF, 213-228.
STRASSER, A., (1994). Milankovitch cyclicity
and high-resolution sequence stratigraphy in
lagoonal–peritidal carbonates (Upper Tithonian–
Lower Berriasian, French Jura Mountains). In:
de Boer, P.L., Smith, D.G. (Eds.), Orbital Forcing
and Cyclic Sequences. Spec. Publ. Int. Assoc.
Sedimentol. 19, 285–301.
STRASSER, A., PITTET, B., HILLGARTNER,
H. & PASQUIER, J.-B., (1999). Depositional
sequences in shallow carbonate-dominated
sedimentary systems: concepts for a highresolution analysis. Sediment. Geol., 128, 201221.
VAIL P.R., MITCHUM R.M., TODD R.G., WIDMIER
J.M., THOMPSON S., SANGREE J.B., BUBB
J.N. & HATLELID W.G. (1977).- Seismic
stratigraphy and global changes of sea level.
In: PAYTON C.E. (Editor), “Seismic stratigraphy
- Applications to Hydrocarbon Exploration”.
A.A.P.G. Mem., 26, 49-212.
References
D’ARGENIO, B., FERRERI, V., AMODIO, S.,
PELOSI, N., (1997). Hierarchy of high-frequency
orbital cycles in Cretaceous carbonate platform
strata. Sediment. Geol. 113, 169–193.
D’ARGENIO, B., FERRERI, V., RASPINI, A.,
AMODIO, S. & BUONOCUNTO, F.P., (1999).
Cyclostratigraphy of a carbonate platform
as a tool for high-precision correlation.
Tectonophysics, 315, 357-385.
D’ARGENIO B., FISCHER A.J., PREMOLI SILVA
I., WEISSERT H. AND FERRERI V. (2004)
Cyclostratigraphy: approaches and case
histories SEPM Special Publication, 81, 311 pp.
GOODWIN P.W. & ANDERSON E.J. (1985)
76
Thirty years of Sequence Stratigraphy: Applications, Limits and Prospects - 2 October 2006 - Bari - Italy
BASE LEVEL VS SEA LEVEL IN SHALLOW-MARINE CLASTIC SYSTEMS:
CON”SEQUENCE” STRATIGRAPHY
Marcello Tropeano1, Piero Pieri1, Luis Pomar2 and Luisa Sabato1
1
Dipartimento di Geologia e Geofisica, Università di Bari, via Orabona 4, 70125 Bari, Italy.
<[email protected]> <[email protected]>
2
Departament de Ciences de la Terra, Universitat de les Illes Balears, 07071 Palma de
Mallorca, Spain. <[email protected]>
corresponds to the base of wave/tide traction;
the topset is mostly composed by shoreface/
nearshore deposits. Examples of these
bodies are high-destructive deltas (wave/tidedominated deltas) and infralittoral prograding
wedges (sensu Hernandez-Molina et al.,
2000). The offlap break corresponds to the
shelf edge (the shoreface edge in: Pomar &
Tropeano, 2001), which in depositional profile
is located at the transition between nearshore
and offshore settings, where a terrace prodeltaor a transition-slope may develop just below the
storm wave base.
Two main problems derive from the fact that the
offlap break may not coincide with the shoreline
(Tropeano et al., 2001):
1) both in ancient sedimentary shallow-marine
successions (showing seaward prograding
foresets) and in high-resolution seismic profiles
(showing shelf wedges), the offlap break is
commonly considered corresponding to the
sea-level (shoreline) and used to inferr paleo
sea-level positions and to construct sea-level
curves. Without a good facies control, this use of
the offlap break might cause a misinterpretation
Sedimentary outcropping lithosomes displaying
subhorizontal topset, basinward prograding
foreset and subhorizontal bottomset are
common in the geological record (i.e. Gilberttype deltas) (fig 1) and most of them show
bedding architectures similar to seismic
reflection patterns of buried bodies (i.e. shelf
wedges) (fig 1).
The position of the topset edge in basin-margin
depositional profiles (the offlap break in the
framework of sequence stratigraphy - Vail et
al., 1991) may vary from the shoreline up to the
shelf break, and it depends on the local base
level. Accordingly, two main groups of bodies
can be differentiated in these clastic systems
(fig 1):
- the base level of the first group is the sea level
(or lake level); the topset is mainly composed by
continental- or very-shallow-water sedimentary
facies and the offlap break practically
corresponds to the shoreline. Examples of
these lithosomes are high-constructive deltas
(river-dominated deltas) and prograding
beaches;
- the base level of the second group
shoreline
fluvial dominated delta
sea level = base level
offlap break
shelf edge
wave-dominated delta or
infralittoral prism
sea level
storm wave-base = base level
fig 1 - On the left, gravelly Gylbert-type delta (from Sabato, 1996); on the top, Quaternary sedimentary
wedge in the NW Mediterranean Sea (from Tesson et al., 1993); on the right, the two alternative
position of the offlap break (from Tropeano et al., 2001).
77
1st offlap break=
beach edge=shoreline
2nd offlap break=
shelf edge=strom wave base
relative sea level changes curve
sea level
storm wave-base
prograding beach lithosome
?
uncorrect relative sea level changes curve
storm wave base changes curve
coeval prograding transition-slope lithosome
fig 2 - Coexistence of two offlap break in the same depositional profile could led to misinterpret
relative sea-level changes recorded in their deposits (after Tropeano et al., 2001).
strandplain, Umiujaq, Hudson Bay, Canada.
Sedimentology, 52, 141-160.
Hernández-Molina F.J., Fernández-Salas L.M., Lobo
F., Somoza L., Diaz-del-Rio V. and Alverinho Dias
J.M. (2000): The infralittoral prograding wedge: a
new large-scale prograda-tional sedimentary
body in shallow marine environments. GeoMarine Letters, 20, 109-117.
Hill P.R., Longuépée H. and Roberge M. (1998). Live
from Canada: forced regression in action; deltaic
shoreface sandbodies being formed. Abstracts,
15th Int. Cong. IAS, Alicante (Spain), 427-428.
Pomar L. and Tropeano M. (2001). The Calcarenite
di Gravina Formation in Matera (southern Italy):
new insights for coarse-grained, large-scale,
cross-bedded bodies encased in offshore
deposits. AAPG Bull., 85 (4), 661-689.
Tropeano M., Pomar L. & Sabato L (2001) - The
offlap break position versus sea-level: a
discussion. Relazione orale. Riassunti 1st annual
conference IGCP 464 “Continental shelves
during the last glacial cycle”, Hong Kong, 25-28
ottobre 2001. 53-54.
Vail P.R., Audemard F., Bowman S.A., Eisner P.N. and
Perez-Cruz (1991). The stratigraphic signatures
of tectonics, eustasy and sedimentology - an
overview. In “Cycles and events in stratigraphy”
(Einsele G., Ricken W. and Seilacher A. eds.),
617-659.
of the ancient sea-level positions and the
inferred relative sea-level changes.
2) both baselevels, the sea level and the
wave/tide base, may govern sedimentary
accumulation in wave/tide dominated shelves
and, consequently, two offlap breaks may
coexist (beach edge and shoreface edge) in
shallow-marine depositional profiles (i.e. Carter
et al., 1991). In this setting, two seawardclinobedded lithosomes, separated by an
“intrasequential” unconformity, may develop
during relative still-stands or falls of the sealevel (Hill et al., 1998; Fraser et al., 2005). In
this case, the two stacked lithosomes could
be misinterpreted as two different systems
tracts, or sequences, and it could led to the
construction of an uncorrect curve of sea-level
changes (fig. 2).
References
Carter R.M., Abbott S.T., Fulthorpe C.S., Haywick
D.W. and Henderson R.A. (1991): Application
of global sea-level and sequence-stratigraphic
models in Southern Hemisphere Neogene strata
from New Zealand. Sp. Publ. IAS, 12, 41-65.
Fraser C., Hill P.R. and Allard M. (2005): Morphology
and facies architecture of a falling sea level
78
Thirty years of Sequence Stratigraphy: Applications, Limits and Prospects - 2 October 2006 - Bari - Italy
THE ‘AGGRADATIONAL HIGHSTAND SYSTEMS TRACT’ (AHST): DEFINITION AND
KEY CHARACTERISTICS
Massimo Zecchin
Istituto Nazionale di Oceanografia e di Geofisica Sperimentale – OGS,
Borgo Grotta Gigante 42/c, 34010 Sgonico (TS)
Recent studies demonstrate that local
factors, such as tectonics, sediment supply,
and basin physiography may produce an
extreme variability in the stratal architecture of
sequences and stacking patterns of systems
tracts. For example, the architecture of deposits
accumulated in growth fault-bounded basins
may be very different from that proposed by
classic sequence-stratigraphic models, which
have been developed for passive, divergent
continental margins (e.g. Posamentier et al.,
1988; Posamentier & Vail, 1988). An example
of these syntectonic successions is provided
by the lower Pliocene Zinga 2 and Zinga 3
stratal units in the Crotone Basin, southern Italy
(Zecchin et al., 2004).
The architecture of these nearshore to lagoonal
and locally continental Pliocene successions,
deposited within kilometer-scale half-graben
sub-basins, typically consists of a relatively
thick (up to 150 m) transgressive systems tract
(TST) in the lower part that grades upward into
a mostly aggradational package (up to 300 m
thick), which has been called ‘aggradational
highstand systems tract’ (AHST) (Zecchin
et al., 2006) (Fig. 1A). Locally, a thin forced
regressive systems tract (FRST) is present
near the top, whereas the lowstand systems
Figure 1. Sequence-stratigraphic models drawn from the stratal architecture of Zinga 2 and Zinga
3 stratal units. (a) A dominant retrogradational to aggradational stacking pattern and the lack of a
maximum flooding surface in the expanded succession that lies in the hanging wall should be noted.
The aggradational interval is called ‘aggradational highstand systems tract’ (AHST). (b) The TST
is locally absent, and the hanging wall succession is composed mostly of the AHST. FRST, forced
regressive systems tract; RS, ravinement surface; RSME, regressive surface of marine erosion; SB,
sequence boundary; TS, transgressive surface. (From Zecchin et al., 2006).
79
tract (LST) is absent (Fig. 1A). The TST may
be absent in some cases, and the resulting
succession is composed of the AHST and
locally of the FRST (Fig. 1B). As the sediment
supply typically kept pace with subsidence
within these fault-bounded basins, significant
fault scarps were not produced during the
deposition (Zecchin, 2005).
The AHST is defined as “an aggradational
package of small-scale cycles deposited above
a transgressive surface or a relatively thick
retrogradational succession interpreted as a
TST” (Zecchin et al., 2006). A distinct maximum
flooding surface is not recognized at the base
of the AHST (Fig. 1A). The AHST resulted
from balanced conditions between the rate of
sediment supply and the rate of creation of
accommodation (Zecchin et al., 2006).
The AHST, therefore, shows significant
differences with respect to a typical HST,
which is characterized by an aggradational to
progradational parasequence set, a shallowing
upward trend, and is marked at the base by
a maximum flooding surface (Van Wagoner,
1988). It is predicted that the AHST passes
laterally into a HST near the fault tips, where the
subsidence rate was lower. The development
of the AHST is favoured in contexts
characterized by relatively rapid fault-controlled
subsidence and a high rate of sediment
supply that compensates the rate of creation
of accommodation. A rapid compressional
or transpressional event that interrupts the
fault-controlled subsidence may lead to the
abrupt interruption of the sedimentation or the
deposition of thin forced regressive strata.
The present example provides interesting
implications
for
sequence-stratigraphic
analyses in extensional fault-controlled basins.
References
Posamentier, H.W. & Vail, P.R. 1988. Eustatic
controls on clastic deposition, II: sequence and
systems tract models. In: Wilgus, C.K., Hastings,
B.S., Kendall, C.G.St.C., Posamentier, H.W.,
Ross, C.A. & Wagoner, J.C. (eds) Sea-level
Changes: an Integrated Approach. SEPM,
Special Publications, 42, 125–154.
Posamentier, H.W., Jervey, M.T. & Vail, P.R.
1988. Eustatic controls on clastic deposition,
I: Conceptual framework. In: Wilgus, C.K.,
Hastings, B.S., Kendall, C.G.St.C., Posamentier,
H.W., Ross, C.A. & Van Wagoner, J.C. (eds)
Sea-level Changes: an Integrated Approach.
SEPM, Special Publications, 42, 110–124.
Van Wagoner, J.C., Posamentier, H.W., Mitchum,
R.M., Vail, P.R., Sarg, J.F., Loutit, T.S. &
Hardenbol, J. 1988. In: Wilgus, C.K., Hastings,
B.S., Kendall, C.G.St.C., Posamentier, H.W.,
Ross, C.A. & Van Wagoner, J.C. (eds) Sealevel Changes: an Integrated Approach. SEPM,
Special Publications, 42, 39–45.
Zecchin, M. 2005. Relationships between faultcontrolled subsidence and preservation of
shallow-marine small-scale cycles: example
from the lower Pliocene of the Crotone Basin
(southern Italy). Journal of Sedimentary
Research, 75, 300-312.
Zecchin, M., Massari, F., Mellere, D. & Prosser,
G. 2004. Anatomy and evolution of a
Mediterranean-type fault bounded basin: the
Lower Pliocene of the northern Crotone Basin
(Southern Italy). Basin Research, 16, 117–143.
Zecchin, M., Mellere, D. & Roda, C. 2006. Sequence
stratigraphy and architectural variability in
growth fault-bounded basin fills: a review of
Plio-Pleistocene stratal units of the Crotone
Basin, southern Italy. Journal of the Geological
Society, London, 163, 471-486.
80
Thirty years of Sequence Stratigraphy: Applications, Limits and Prospects - 2 October 2006 - Bari - Italy
SEQUENCE STRATIGRAPHY OF HOLOCENE DEPOSITS IN THE VENICE AREA
BASED ON HIGH-RESOLUTION SEISMIC PROFILES
Massimo Zecchin1, Giuliano Brancolini1, Federica Donda1, Federica Rizzetto2 and
Luigi Tosi2
Istituto Nazionale di Oceanografia e di Geofisica Sperimentale – OGS,
Borgo Grotta Gigante 42/c, 34010 Sgonico (TS)
2
Istituto di Scienze Marine – Consiglio Nazionale delle Ricerche, San Polo 1364, 30125
Venezia
1
High resolution seismic profiles, carried out
within the Co.Ri.La. 3.16 Research Line and
the CARG Project, have allowed a sequencestratigraphic analysis of the Holocene deposits
located off the Venice Lagoon. The sequence
is bounded at the base by an unconformity
(the sequence boundary) well recognizable in
seismic profiles (Figs. 1-3), which is up to 22
Figure 1. Transgressive and highstand deposits off the Lido barrier island. The red line represents the
sequence boundary of the Holocene sequence, whereas the blue line is a wave ravinement surface
that coincides with the downlap surface of the prograding marine clinoforms.
Figure 2. Inferred estuarine channel fill deposit forming part of the TST (lower part of the Holocene
sequence). Lateral accretion is well recognizable. The base of the channel is the sequence boundary.
In this relatively distal location, the HST of the Holocene sequence is absent.
Figure 3. Ebb tidal delta off the Chioggia inlet. This deposit is part of the HST of the Holocene
sequence. Note the downlap of clinoforms on the sequence boundary (red line) and the absence of
transgressive deposits. The dunes on the left are part of the fill of the Chioggia inlet.
81
m deep from ground surface in the southern
Venetian littoral and tends to outcrop landward
and seaward.
In the lower part of the Holocene sequence,
zones showing sub-horizontal and hummocky
reflectors are separated by channelized
deposits, interpreted as fluvial or estuarine
channel fills, and channel-levee systems,
interpreted as distributary channels (Figs.
1 and 2). Core data demonstrate that backbarrier strata overlie the sequence boundary in
correspondence of the Lido barrier island. The
lower part of the Holocene sequence has not
been recognized off the Chioggia inlet (Fig. 3).
A sharp surface, climbing landward, truncates
the lower Holocene deposits and is overlain by
a prograding marine wedge, which represents
the upper part of the sequence (Fig. 1). This
wedge is up to 10 m thick in landward locations,
and consists of a regressive shoreface-shelf
system and, locally, of ebb tidal deltas off the
lagoon inlets (Figs. 1 and 3).
The lower part of the Holocene sequence has
been interpreted as a transgressive systems
tract (TST), deposited during the high-amplitude
sea-level rise that followed the Last Glacial
Maximum (Figs. 1 and 2). A wave ravinement
surface (WRS) marks the marine ingression
during the late transgressive phase, and is
approximately coincident with the downlap
surface (DLS) in seismic profiles (Fig. 1).
The prograding marine wedge represents the
highstand systems tract (HST) of the sequence
(Figs. 1 and 3). During the latter phase, the rate
of sediment supply outpaced that of the creation
of accommodation. The variable thickness
distribution of the TST (Figs. 1-3) documents
important changes in the stratal architecture of
the sequence along both depositional strike and
dip, which may be in part due to the antecedent
basin physiography.
82
Thirty years of Sequence Stratigraphy:
Applications, Limits and Prospects
PARTICIPANTS - INDEX
TST - HST
HST
TST
incised valley
fills
HST
HST TST
FSST
LST
SMST
TST
LST
sb1
older sequence
FSST
sb2
sb1
sb1
Thirty years of Sequence Stratigraphy: Applications, Limits and Prospects - 2 October 2006 - Bari - Italy
Thirty years of Sequence Stratigraphy: Applications, Limits and Prospects - 2 October 2006 - Bari - Italy
Thirty years of Sequence Stratigraphy: Applications, Limits and Prospects - 2 October 2006 - Bari - Italy
A. Albianelli, A. Bertini, C. Lombardi, M. Moretti, G. Napoleone & L. Sabato Cyclicity in the lower and middle Pleistocene San Lorenzo lacustrine succession
of the Sant’Arcangelo Basin (Southern Apennines, Italy): magnetic, palynologic
and sedimentary signals.
41
A. Amorosi - Application of sequence stratigraphic concepts to a highly subsiding
basin: the example of the Po Plain.
29
R. Bersezio - Aquifer characterization and hydrostratigraphy of alluvial sediments:
taking advantage of sequence stratigraphy methods.
33
F. Chiocci - Depicting correlative conformities on high-resolution seismic data.
23
A. Cilumbriello, L. Sabato, M. Tropeano, S. Gallicchio, A. Grippa & P. Pieri Stratigraphic arrangement of the “Regressive coastal deposits” of the Bradanic
Trough (Basilicata, southern Italy): subsidence, uplift, and high-frequency sealevel changes.
43
B. D’Argenio & V. Ferreri - Cyclo- and sequence-stratigraphy: the case of shallow
water carbonates.
3
D. De Benedictis - The interplay amongst trophic regime, carbonate feedback
system and changes in stratigraphic accommodation space: an investigation
based on the palaeoecological analysis of the microbenthic assemblages in
two case studies of the Early Cretaceous shallow-water carbonates.
47
M. Delle Rose - Some features of the Pliocene – Lower Pleistocene sequence of the
southeastern Salento.
49
M. Delle Rose & F. Resta - Stratigraphic and sedimentological insights about the
Capo San Gregorio breccias and conglomerates (South Salento).
53
B. Haq - Hystorical development of sequence stratigraphy.
1
B. Haq - The new Global Cycles Chart.
1
A. Irace, M. Natalicchio, P. Clemente, S. Trenkwalder, P. Mosca, R. Polino, D.
Violanti & D.A. De Luca - Stratigraphic architecture and deep hydrostratigraphy
in the Pliocene to Holocene deposits of the Western Po Plain.
57
S. Longhitano - Sequence stratigraphy of the Potenza Basin Pliocene coarsegrained deltas (southern Italy): recognition of medium- and high-frequency
relative sea-level oscillations during the sedimentation.
61
Thirty years of Sequence Stratigraphy: Applications, Limits and Prospects - 2 October 2006 - Bari - Italy
D. Masetti - Upper Triassic and Lower Jurassic thickening-upward, subtidal cycles
in the Southern Alps: from the ramps to the lagoons.
9
A. Milia - Sequence stratigraphy in volcanic settings: examples from the Campania
Margin.
35
S. Milli - The sequence stratigraphy of the Quaternary successions: implications
about the origin and filling of incised valleys and the mammal fossil record.
27
G.G. Ori - Sequence stratigraphy of deltaic and shallow lacustrine deposits,
Juventae Chasma (Mars).
21
G.G. Ori - Continental sequences in Sahara dominated by climatic changes
65
M. Pistis, A. Loi, F. Leone, E. Melis, A.M. Caredda & M.P. Dabard - Architettura
deposizionale degli accumuli a minerali pesanti (placers): esempio
nell’Ordoviciano della Sardegna e della Bretagna - (Stacking Pattern of heavy
minerals enrichment (placers):example of the Ordovician of Sardinia and
Brittany).
67
L. Simone & G. Carannante - Foramol (temperate-type) vs chlorozoan (tropicaltype) carbonate platforms: depositional dynamics and architecture of the
related depositional systems.
19
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81