GS5 - Sedimentary and Biological Processes
TS5.3
Mediterranean Sea as natural laboratory for active processes at seabed
(fluid, mass waiting, seismicity)
CONVENERS
Jean Mascle (Geoazur, Observatoire de la Côte d’ Azur, Nice, France)
Silvia Ceramicola (OGS Trieste)
Rend. Online Soc. Geol. It., Vol. 21 (2012), pp. 946-947,1 fig.
© Società Geologica Italiana, Roma 2012
Recent mass-wasting processes and related geohazard at Stromboli
and Vulcano (Italy)
DANIELE CASALBORE (*), CLAUDIA ROMAGNOLI (**), ALESSANDRO BOSMAN (*), FRANCESCO LATINO CHIOCCI (°)
Key words: submarine landslide, multibeam, La Fossa caldera,
Sciara del Fuoco, Aeolian Islands.
INTRODUZIONE
Stromboli and Vulcano islands are two active volcanoes
located in the Aeolian Arc (Southern Tyrrhenian sea). Their
submarine portions account for about 98% and 80% of the whole
extent of volcanic edifice, respectively (BOSMAN et alii, 2009;
ROMAGNOLI et alii, 2012). The flanks of these volcanic edifices
are very steep and covered by volcaniclastic sediments due to a
large spectrum of mass-wasting processes, ranging from largescale sector collapses to small landslides (CASALBORE et alii,
2011; ROMAGNOLI et alii, 2012). The geohazard related to these
processes is very high, as demonstrated by the occurrence of a
medium-scale tsunamigenic landslide on 30 December 2002 at
Stromboli (Fig 1a; CHIOCCI et alii., 2008).
Fig. 1 – Residual map (scale bar units are in meters) obtained as difference between pre- and post-“2002 Stromboli landslide” draped over the shaded relief of
Sciara del Fuoco slope at Stromboli volcano; the red dashed line indicates the limit of the subaerial landslides; three pre- and post-landslide cross-section of
2002 landslide scar are also shown (modified from Casalbore et alii, 2012). b) La Fossa Caldera emerged and submerged sectors, with the indication of the 1988
tsunamigenic landslide and erosive gullies (white arrows, modified from Romagnoli et alii, 2012); the location maps of the Fig. 1a and b are reported in the inset
_________________________
(*) Istituto di Geologia Ambientale e Geoingegneria, CNR
(**) Dipartimento di Scienze della Terra e Geologico-Ambientali,
Università Alma Mater di Bologna
(o) Dipartimento di Scienze della Terra, Università Sapienza di Roma
This reseach has been partially funded by MaGIC (Marine Geohazard
along the Italian Coast) project
The aim of this work is to depict recent mass-wasting and
erosive processes that affect the submarine flank of these
volcanic edifices, with particular reference to the areas offshore
two very active sectors, i.e. the Sciara del Fuoco at Stromboli
(Fig. 1a) and La Fossa caldera at Vulcano, where a small
tsunamigenic landslide occurred in April 1988 (Fig. 1b; TINTI et
alii, 1999). This task has been realized through the integration of
multibeam, long-range side scan sonar and seismic data collected
in the last 20 years from IGAG-CNR of Rome and the
Universities of Rome (Sapienza) and Bologna.
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REFERENCES
BOSMAN, A., CHIOCCI, F.L., ROMAGNOLI, C., (2009) - Morphostructural setting of Stromboli volcano, revealed by highresolution bathymetry and backscatter data of its submarine
portions. Bullettin of Volcanology, 71, 1007-1019.
CASALBORE, D., ROMAGNOLI, C., BOSMAN, A., CHIOCCI, F.L.
(2011) - Potential tsunamigenic landslides at Stromboli
Volcano (Italy): Insights from marine DEM analysis.
Geomorphology, 126, 42-50.
CASALBORE D., BOSMAN A., CHIOCCI F.L. (2012) - Study of
recent small-scale landslides in geologically active marine
areas through repeated multibeam surveys: examples from
the Southern Italy. In: Y. Yamada, et alii (Eds.) - Submarine
Mass Movement and Their Consequences, "Advances in
Natural and Technological Hazards Research" Series, 31,
573-582. Doi: 10.1007/978-94-007-2162-3_51.
CHIOCCI, F.L., ROMAGNOLI, C., TOMMASI, P., BOSMAN, A.,
(2008) - The Stromboli 2002 tsunamigenic submarine slide:
characteristics and possible failure mechanisms. Journal of
Geophysical Research, 113, B10102.
ROMAGNOLI C., CASALBORE D., CHIOCCI F.L (2012) - La Fossa
Caldera breaching and submarine erosion (Vulcano Island,
Italy). Marine Geology, 303-306, 87-98.
TINTI, S., BORTOLUCCI, E., ARMIGLIATO, A., (1999) - Numerical
simulation of the landslide induced tsunami of 1988 on
Vulcano Island, Italy. Bullettin of Volcanology, 61, 121-137.
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© Società Geologica Italiana, Roma 2012
Size Distribution of Submarine Landslides along the Gioia Basin.
Tyrrhenian Sea (Italy)
D. CASAS (*), F. CHIOCCI, D. CASALBORE (**) & G. ERCILLA (°)
Key words: Geohazard, Gioia Basin, Statistical distribution,
Submarine slides .
INTRODUCTION
The magnitude-frequency relationship of sedimentary
instabilities is essential for a proper hazard assessment at regional
scale. The distribution of sedimentary instabilities, their
recurrence of certain sizes, and triggering mechanisms are
variables for determining their potential hazard. Regional
inventories that incorporate these variables represent the first step
to establish the probability of triggering a sedimentary instability,
with certain dimensions, and during a period of time.
For subaerial landslides, it has been suggested the cumulative
number-area and cumulative number-volume relationships can be
described by inverse power-law distributions based on the
dimensions of the failure scar, slide deposits or headwall length
(GUZZETTI et alii, 2002; DUSSAUGE et alii, 2003, Guthrie and
Evans, 2004, MALAMUD et alii, 2004). In the marine
environment, those relationships have resulted successful for a
few studied cases (TEN BRINK et alii, 2006; MICALLEF et alii,
2008). In most of those studies the inverse power law distribution
only explained a truncated portion of mapped inventories, and the
size distribution appeared to fit a log-normal distribution. In these
cases, normal distribution was often attributed to an
undersampling of landslides with a given size range.
The distribution based on the inverse power law results from
a self-organized critical behavior. This implies that from
equivalent initial conditions, a series of events resulting from
additive processes can be generated. This is explained, in terms
of instability processes, by the fact that the metastable region on
which the instability is propagated once initiated, can grow by
coalescence of smaller regions. By contrast a log-normal
distribution implies that the metastable region is destabilized
instantly. Then, the final size of a landslide depends on the
characteristics of the trigger (e.g. magnitude) and adjusts for
local variations such as slope, strength etc.
_________________________
(*) Instituto Geológico y Minero de España, IGME. Tres Cantos 28760,
Madrid
(**)Universita de Roma “La Spienza”. Pz. Aldo Moro 5. 00185 Roma.
(°)ICM-CSIC. P. Marítim de la Barceloneta 08003. Barcelona.
This work has been developed in the framework of the MAGIC project and
the “José Castillejo” program (JC010-134).
The work here presented is based on the analysis of
geological and geomorphological characteristics of a large area
of Gioia Basin, in the Tyrrhenian Sea (Fig. 1), in order to
generate interpretive maps that allow the identification and
characterization and spatial distribution of sedimentary
instabilities.
GEOLOGICAL FRAMEWORK
The Gioia Basin is an intra-slope basin located between the
NE margin of Sicily and S Calabria, and is divided into two subbasins (N and S) by the Acquarone structural high. In the
southern margin of Calabria, this structural high separates also
another intra-slope basin called Palmi (Fig. 1). The continental
shelf is practically absent along the margin of Calabria, although
locally it is about 5 km wide along the northeast coast of Sicily,
facing the structural high Acquarone. The N Gioia Basin (NGB),
limited laterally by structural highs, shows as a main
morphological feature the Gioia-Mesima canyon/channel system
(GMS). This system is characterized by a double head defining
the canyons Gioia and Mesima that evolve to channels with the
same name beyond the foot of slope (COLANTONI et alii, 1992).
The GMS system is tributary of Stromboli valley (CASALBORE,
2009, 2011).
METHODOLOGY
The development of this work has been done on the basis of
bathymetric data acquired in the framework of the MAGIC
project (Map of Geohazard-related features of the seafloor of
Italy) which aims to make the mapping of geological hazards
along the Italian margins. The methodology for this study is
based on the characterization and mapping of each of the
instabilities as well as the definition of their headwalls. This has
allowed calculating the position and length of the scars, their
area, and the volume of sediment mobilized.
The volume of sediment has been calculated using Digital
Elevation Model and GIS tools. The protocol is based on 4 key
steps: 1) definition of the boundaries of the headwalls, 2) export
of those limits (x, y, z) for generation a surface simulating the
initial seafloor conditions, 3) extraction of the surface that
defines the post-slide area, and 4) calculation of volume by
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Fig. 1 – Bathymetry of the study area (dashed line). (B) Detail of the instabilities mapped on the margins of Gioia and Mesima channels.
superimposing the two surfaces.
The minimum size of an identifiable instability is a function
of resolution bathymetric. This resolution is higher in shallow
areas. For this reason the instabilities defined by a perimeter of
less than 0.10 km have been dismissed.
the smallest one is located at 19 m depth, and has a scar of 50 m
long. The headwall area covers 171 m2 and involves a sediment
volume of 200 m3.
DISCUSSION AND CONCLUSIONS
RESULTS
We have studied the geology and geomorphology
characteristics of an area of about 3350 km2 in the Gioia Basin
which has allowed the identification and characterization of 420
landslides. These landslides affect an area over 87 km2 and are
responsible for the mobilization of about 1.5 km3 of sediment.
The 59% of instabilities are located in the heads and sidewalls of
the canyons and channels, like MSG and Acquarone (Fig. 1). The
remaining 41% are located in the open slope and the walls of
structural
highs
bounding
the
the
Gioia
Basin.
The largest landslide occurs in the slope at 1500 m water depth
and is defined by a scar of 7 km long. The headwall area covers
11 km2 and involves a sediment volume of 0.4 km3. By contrast,
Bibliographic compilation about the Mediterranean Sea
published by CAMERLENGHI et alii, 2010, indicates that the
mapped instabilities in this sea are relatively small in size with
respect others, for example from N Atlantic. That inventory
identifies a total of 532 sedimentary instabilities. Most of them
(419) have a size between 10 and 103 km2 and only 77 display
sizes less than 10 km2. However that inventory lacks of
observations of smaller sedimentary instabilities. By contrast, the
inventory carried out in this work represents an opportunity to
improve the statistical significance of the frequency distribution
at different spatial scales. This is because it incorporates a large
number of measurements in small landslides (<10km2) which are
often unrepresented or undersampled. Likewise, our observations
practically equal to the total number of instabilities described in
the Mediterranean covering only a small area of the Tyrrhenian
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Sea (420 vs. 532).
The cumulative number-volume distribution of the
instabilities described in this work, can be described by a lognormal distribution (Fig. 2). This would reinforce the findings of
other authors in the marine environment (TEN BRINK et alii, 2006
among others). Confirmation of this distribution should be made
by the individual analysis of each different populations observed
in the different environments defined (channel / canyon, slope,
structural highs). This analysis in different geological
environments can provide valuable information not only on the
dynamics of the landslide processes but also on the impact on the
evolution of a particular environment such as the evolution of a
channel / canyon.
Fig. 2 – Cumulative number-volume distribution of the total instabilities
described in this work. Red line represents the log-normal distribution
(R2=0.9734).
REFERENCES
CASALBORE (2009) - Studio di fenomeni d’instabilità gravitativa
sui fondali marini, con particolare riferimento all’isola di
Stromboli. PhD Thesis. University of Bolonia.
CASALBORE, D., ROMAGNOLI, C., BOSMAN, A. & CHIOCCI, F.
(2011)- Potential tsunamigenic landslides at Stromboli
Volcano (Italy): Insight from marine DEM analysis.
Geomorphology, 126. 42-50.
CAMERLENGHI A, URGELES R, FANTONI L (2010 )- A database on
submarine landslides of the Mediterranean Sea. In: DC
Mosher, L Moscardelli, RC Shipp, JD Chaytor, CDP Baxter,
HJ Lee, R Urgeles (eds)- Submarine mass movements and
their consequences, advances in natural and technological
hazards research. Springer. 28 491–501.
COLANTONI, P., GENNESSEAUX, M., VANNEY, J.R., ULZEGA, A.,
MELEGARI, G. AND TROMBETTA, A. (1992) - Processi
dinamici del canyon sottomarino di Gioia Tauro (Mare
Tirreno). Giorn.Geol., 54, 199–213.
DUSSAUGE, C., GRASSO, J., HELMSTETTER, A., (2003) - Statistical
analysis of rockfall volume distributions: implication for
rockfall dynamics. J. Geophys. Res. 108 (B6), 2286.
doi:10.1029/2001JB000650.
GUTHRIE, R.H., EVANS, S.G., (2004) - Analysis of landslide
frequencies and characteristics in a natural system, coastal
British Columbia. Earth Surf. Process. Landf. 29, 1321–1339.
GUZZETTI, F., MALAMUD, B., TURCOTTE, D., REICHENBAC, P.
(2002) - Power-law correlations of landslide areas in central
Italy. Earth and Planetary Science Letters, 195, 169-183.
MALAMUD, B.D., TURCOTTE, D.L., GUZZETTI, F., REICHENBACH,
R., (2004) - Landslide inventories and their statistical
properties. Earth Surf. Process. Landf. 29, 687–711.
MICALLEF, A., BERNDT, C., MASSON, D.G., STOW, D.A.V.,
(2008) - Scale invariant characteristics of the Storegga Slide
and implications for large-scale submarine mass movements.
Mar. Geol. 247, 46–60.
TEN BRINK, U.S., GIEST, E.L., ANDREWS, B.D., (2006) - Size
distribution of submarine landslides and its implication to
tsunami hazard in Puerto Rico. Geophys. Res. Lett. 33,
doi:10.1029/2006GL026125.
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Seabed mapping for geohazard in the Gulf of Taranto, Ionian Sea
(Southern Italy)
S. CERAMICOLA (*), M. R. SENATORE (**), M. COSTE (*), A. MEO (**), M. BOSCAINO (**), A. COVA (*)
Key words: Geohazard, Gulf of Taranto, seabed morphology.
sedimentary processes
The seabed features of the Gulf of Taranto are the
morphological expression of the geological processes that have
occurred in this area during the Calabrian Arc subduction, where
the Adria, European and African plates converge, in the NE side
of the Ionian Sea. This area is characterized mainly by three
different adjacent geomorphological domains: 1) the Calabrian
margin, characterized by the deformations of the southern
prolongation of the Appennines Chain (to the west) the Taranto
valley, the seabed morphologic expression of the Bradanic
foredeep (in the center) and 3) the Apulian margin, characterized
by the western termination of the Apulian Ridge.
This area have been the object of several new geophysical
investigations in the last years and the results have been used to
carry out the first seabed mapping of the Gulf of Taranto seabed
features in order to assess geohazards and risk related to
geological processes for the coastal areas. This work has been
carried out under the framework of the Magic Project (Marine
Geohazards Along The Italian Seas), funded by the department of
the Civil Protection of Italy.
We here present the first high-resolution seafloor and
geohazard maps of the Gulf of Taranto obtained integrating
swath-bathymtry, side-scan sonar, subbottom data, seismic
reflection profiling and literature information from previous
studies. Main geomorphological seabed features and domains
have been defined, and they have been associated to main
geological processes (sedimentary and tectonic) occurred in this
area. Canyons at different stages of development -some of them
showing important retrogressive activity, diffuse erosional alongslope features, faults depicting the seafloor at different locations,
gas seepage and landslide scars are some of the most prominent
features identified that could present an hazard for coastal areas.
All these active features observed in the Gulf of Taranto seafloor
may seriously endanger human society especially in coastal areas
where most of the population reside, but also in deeper sea,
where oil/gas pipelines and cables are located; our results are
relevant to both monitoring of these features through time and to
gain a good knowledge of their functioning.
REFERENCES
Figura 1 Seabed mapping of the Apulian margin. Color lined indicate
major morphological lineaments. Contours are marked every 50m.
_________________________
(*) Istituto Nazionale di Oceanografia e Geofisica Sperimentale – OGS,
Borgo Grotta Gigante 42/c, 34010 Sgonico (TS) Italy
([email protected])
(**) Dipartimento di Scienze per la Biologia, la Geologia e l’Ambiente
Palazzo Inarcassa, Università degli Studi del Sannio, Via dei Mulini, 59/A
Benevento – Italy
This work has been carried out in the framework of the MAGIC Project
(Marine Geohazards along the Italian Coasts) funded by the Italian
Department of the Civil Protection.
BELFIORE A., BONADUCE G., GARAVELLI G., MASCELLARO P.,
MASOLI M., MIRABILE L., MONCHARMONT M.,MORETTI M.,
NUOVO G., PENNETTA M., PESCATORE T., PLACELLA B.,
PUGLIESE N., RUSSO B., SENATORE M.R., SGARRELLA F.,
SANSONE E., SPEZIE G., THOREZ J., TRAMUTOLI M. &
VULTAGGIO M. (1981) - La sedimentazione recente del Golfo
di Tranto (Alto Ionio, Italia). Ann. Ist. Univ. Navale, Napoli,
49-50, 3, 1-196.
CERAMICOLA, S., CABURLOTTO, A., COSTE, M., COVA A,
MIGEON, S., FORLIN, E. PRAEG, D., DIVIACCO, P., COTTERLE,
D., ROMEO, R., FACCHIN, L., CIVILE, D., RAMELLA, R.,
CRITELLI, S. & CHIOCCI, F. L. (2010) - Seabed features in
relation to geohazards on the Ionian Calabrian margin:
results from the MAGIC Project. IN: 39TH CIESM CONGRESS.
ISSN: 0373-434X
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COSTE M., MIGEON S., CERAMICOLA S., MASCLE J., FORLIN E., &
PRAEG D. (2010).- Processus de formation et d’évolution des
canyons sous-marins sur la marge ouest du bassin ligure.
23ème Réunion des Sciences de la Terre (RST), 25-29 octobre
2010, Bordeaux, France. Abstract Poster n° 160, 2 ème Prix du
concours du meilleur poster, in Livre des Résumés, pp. 73-74.
COVA A. S. CERAMICOLA A. CABURLOTTO, L. SORMANI, I.
TOMINI & F. ZGUR (2009) - MAGIC 0409 Expedition report.
OGS internal report 120pg.
FARANDA M.G. (2005) - SEGNALI CLIMATICI E VARIAZIONI
AMBIENTALI NEI SEDIMENTI DI CAROTAGGI NELL’OFFSHORE DI
METAPONTO (GOLFO DI TARANTO). Aspetti sedimentologici e
analisi isotopiche. Tesi di Dottorato, Università degli Studi
del Sannio, pp.211.
PESCATORE T. & SENATORE M.R. (1986) – A comparison
between a present-day (Taranto Gulf) and Miocene (Irpinian
Basin) foredeep of the Southern Apennines (Italy). Spec.
Publs int. Ass. Sediment., 8, 169-182.
SELLI R. & ROSSI S., (1975) – The main geologic features of
Ionian sea. Rapp. Comm. Int. Mer. Medit., 23, (4a), 115-116.
SENATORE M.R. (1987)- CARATTERI SEDIMENTARI E TETTONICI
DI UN BACINO DI AVANFOSSA. Il Golfo di Taranto. Boll. Soc.
Geol. It., 38, 177-204.
SENATORE M.R., NORMARK W.R., PESCATORE T., & ROSSI S.
(1988) – Structural framework of the gulf of Taranto (Ionian
Sea). Mem. Soc. Geol. It., 41, 533-539.
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© Società Geologica Italiana, Roma 2012
Reconstruction of a submarine landslide and related tsunami from
morpho-bathymetry and sub-bottom data on the Ionian Calabrian
margin (Mediterranean Sea)
S. CERAMICOLA (*), S. TINTI (**), F. ZANIBONI (**), D. PRAEG (*), P. PLANINSEK (***)
Key words: Ionian Calabrian Margin, morpho-bathymetry
sub-bottom data, submarine slide, tsunami modelling
Submarine landslides are natural phenomena that transport
marine sediment down continental slopes into deep-marine
environments. Landslides can be triggered by a number of
different causes, either internal (such as changes in physical
chemical sediment properties) or external (e.g. earthquakes,
volcanic activity, salt movements, sea level changes etc.).
Landslides may mobilize sediments in such a way as to form
an impulsive vertical displacement of a body of water,
originating a wave or series of waves with long wavelengths
and long periods called tsunamis (‘harbor waves’).
The aim of this work is to reconstruct the volume and
dynamics of a submarine landslide on the tectonically active
Ionian Calabrian margin (ICM). The study is based on
geophysical data - morpho-bathymetry (Reson 8111, 8150) and
sub-bottom profiles (7-10KHz) - collected aboard the research
vessel OGS Explora in the framework of the MAGIC Project
(Marine Geohazard along the Italian Coasts), funded by the
Italian Civil Protection
Morpho-bathymetric data reveal headwall scars up to 50 m
high across water depths of 700 1400 m, while sub-bottom
profiles indicate stacked slide deposits at and near seabed. We
estimate that the failure mobilized ca. 2 km3 of sediment, over
at least 15 km from the headwall. Together the data enable the
reconstruction of the landslide dynamic considering two
possible scenarios: 1) the landslide mobilized in two steps
(conservative scenario); 2) the landslide mobilized all the
sediment in a single step (most dramatic scenario). On the
basis of these two scenarios we attempt to mathematically
model the failure and simulate the tsunami that would have
been generated by the considered volume of sediment.
Fig 2 . Tsunami propagation at different time steps, over the
near field computational domain G1. The positive signal,
meaning sea ingression is marked with the yellow-red scale, the
negative measure, accounting for sea withdrawal, with the
cyan-blue scale
.
Fig 1 - Reconstructions of the Assi failure dynamic.
The geophysical data provide evidence that the ICM has
been exposed during recent time to multiple failure events.
_________________________
(*) Istituto Nazionale di Oceanografia e Geofisica Sperimentale – OGS,
Borgo Grotta Gigante 42/c, 34010 Sgonico (TS), Italy
([email protected])
(**) Settore di Geofisica, Dipartimento di Fisica, Università di Bologna, via
Carlo Berti Pichat 8, 40127 Bologna, Italy
(***) Via Doberdò 26/2 Opicina, Trieste, Italy
This work has been carried out in the framework of the MAGIC Project
(Marine Geohazards along the Italian Coasts) funded by the Italian
Department of the Civil Protection in Collaboration with the University of
Trieste (Engineering Department)
Numerical simulations have been performed using the
numerical codes developed by the University of Bologna
research team. We have computed the motion of the mass, the
tsunamigenic effects of the motion on the sea water and the
propagation of the tsunami waves. We have assessed the main
tsunami features such as travel times, main wave period,
polarity of the first arrival, maximum wave elevation,
providing a complete picture of the coastal hazard associated to
such event. It has been found that the area most affected in this
tsunami scenario is the stretch of coast about 25 km long
between Roccella Jonica and Monasterace on the eastern side
of Calabria. Even if the resulting waves have limited amplitude
they can cause relevant damage to the infrastructures located
close to the shoreline.
Assessments of tsunami arrival time in adjacent coastal
areas, period and wavelength of the tsunami and implication
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for coastal geohazards have been formulated for the Calabrian
margin (small scale) and extrapolated to adjacent margins of
the Mediterranean basin (large scale).
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FANUCCI. & S. CRITELLI. (2010) - Submarine mass wasting
on the Ionian Calabrian margin. Poster presentation at the
AGU Fall Meeting, S. Francisco. 13-17 December 2010.
Abstract OS13E-1295
PLANINSEK (2011) - Analisi morfobatimetrica e sismica di una
frana sottomarina nel margine calabro ionico e
simulazione numerica del conseguente tsunami. Thesis
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PLANINSEK P., S. CERAMICOLA, I. MARSON, F. ZANIBONI, S.
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and related tsunami from morpho-bathymetry and subbottom data on the Ionian Calabrian margin (Medit. Sea)
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TINTI S., CHIOCCI F.L., ZANIBONI F., PAGNONI G., & DE
ALTERIIS G. (2011) - Numerical simulation of the tsunami
generated by a past catastrophic landslide on the volcanic
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for Geohazard Assessment, Marine Geophysical
Researches, 32, 287-297.
TONINI R., ARMIGLIATO A., PAGNONI G., ZANIBONI F. & TINTI
S. (2011) - Tsunami hazard for the city of Catania, eastern
Sicily, Italy, assessed by means of Worst-case Credible
Tsunami Scenario Analysis (WCTSA), Nat Hazards Earth
Syst Sci, 11, 1217–1232.
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© Società Geologica Italiana, Roma 2012
Different morpho-structural canyon systems observed on the Ionian
margin (Calabria, Italy)
COSTE M. (1,2), CERAMICOLA S. (1), MIGEON S. (2), FORLIN E. (1) & COVA A. (1)
Key words: Canyon maturity, Ionian Calabrian margin,
Ramification degree, Seabed morphology and morphometric
analysis, Sub-botton data, Swath-bathymetry
INTRODUCTION
Sediment transfer from the continental shelf to the deepbasin is a great interest as it partially controls the morphological
and architectural evolution of continental margins. Downslope
transfer of sediments via processes of erosion and deposition
result in the construction of typical features such as submarine
canyons. Because they strongly erode the continental slope,
canyons contribute significantly to its morphological evolution
through time.
This study aims to better understand the processes of
formation and evolution of nine canyon systems identified on the
Ionian Calabrian margin. In particular, two systems of canyons,
the Corigliano system (in the north) and the Squillace system (in
the south) have been taken as example to show the differences of
their morpho-structural characteristics. Analyses of seabed
morphology and morphometry have been carried out using swath
bathymetry data and sub-bottom profiles, acquired by the OGS
Explora vessel, along the Ionian Calabrian margin, in the frame
of the Italian project MAGIC (MArine Geohazards along the
Italian Coasts) funded by the Department of Civil Protection.
This work is also part of a larger study which aims to compare
canyon dynamics in the Calabrian and the Ligurian continental
margins.
Main morphometric characteristics of the canyons
(ramification degree, length, width, depth, incision shape, slope
gradient, sinuosity index) have been analyzed in order to better
understand their origin, construction mechanisms and evolution
in relation to the regional geological context. We also studied the
main characteristics of the fluvial system that could be associated
to each canyon (area drainage, main slope gradient, length,
theorical suspended sediment concentration and monthly
discharge), to better understand what are the relations between
rivers and submarine canyons.
In this work we show how submarine canyons adjust to
the general evolution of the margin topography and could be used
as markers of its deformation. The northern example; the
Corigliano system; exhibits a poorly ramification gradient, a
longitudinal thalweg convex-trend and low incision parameters
(i.e. incision depth and incision width). Corigliano shows poorly
branched and dendritic heads which are associated to relative
large watersheds. On the contrary the southern example; the
Squillace system; exhibits a higly ramification degree, a concavetrend longitudinal profile and relative high incision parameters
(i.e. incision depth and incision width). Squillace heads are
highly branched and are associated to smaller watersheds.
The overall objective, once analyzed all the nine
canyons systems will be to bring new insights on the canyon
degree of maturity and being able to discriminate between
“juveniles” and “matures” canyons along the Ionian Calabrian
margin. The information provided by the canyon morphometry of
the Calabrian Margin are used to speculate on which factors
controlled their formation and evolution, in relation to the
regional geological context of this tectonically active margin.
FIGURE
_________________________
(1) OGS (Istituto di Oceanografia e di Geofisica Spreimentale) (Borgo
Grotta Gigante, 42/c 34010 Sgonico (TS) Italia)
(2) GéoAzur (villefranche-sur-mer France) / OGS (Borgo Grotta GiganteItalie) (observatoire Océanologique UMR6526 GéoAzur Port de la Darse
06235 Villefranche-sur-Mer
Fig. 1 – ID card of the Corigliano and the Squillace systems, presenting
morphometric characteristics.
Lavoro eseguito bell’ambito del progetto ... con il contributo finanziario
della Protezione Civile Italiana
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18-20 SETTEMBRE 2012, ARCAVACATA DI RENDE (CS)
Fig. 2 – The Corigliano and the Squillace system of canyons, presenting different evolution of their heads morphology (poorly branched in the Corigliano sytem,
and highly branched in the Squillace system), a different ramification degree and a different longitudinal profile of the main thalwegs, and different
characteristics of the watersheds associated.
REFERENCES
CERAMICOLA S., CABURLOTTO A., COSTE M., COVA A., MIGEON
S., FORLIN E., PRAEG D., DIVIACCO P., COTTERLE D., ROMEO
R., FACCHIN L., CIVILE D., RAMELLA R., CRITELLI S. &
CHIOCCI F. L.. (2010) – Seabed features in relation to
geohazards on the Ionian Calabrian margin: results from the
MAGIC Project. In: 39th CIESM Congress. ISSN: 0373434X.
COVA A., CERAMICOLA A., CABURLOTTO L., SORMANI L.,
TOMINI I. & ZGUR F. (2009) – MAGIC 0409 Expedition
Report. OGS Internal report 120pg.
MORELLI D., CUPPARI A., COLIZZA E. & FANUCCI F. (2011) –
Geomorphic setting and geohazard-related features along the
Ionian Calabrian margin between Capo Spartivento and Capo
Rizzuto (Italy). Mar. Geophys. Res., 32 (1-2), 139-149.
MULDER T. & SYVITSKI J. P. M. (1995) – Turbidity currents
generated at river mouth during exceptional discharges to the
world ocean. J. Geol., 103, 285-299.
REBESCO M., NEAGU R. C., CUPPARI A., MUTO F., ACCETELLA
D., DOMINICI R., COVA A, ROMANO C. & CABURLOTTO A.
(2009) – Morphobathymetric analysis and evidence of
submarine mass movements in the western Gulf of Taranto
(Calabria margin, Ionian Sea). Int. J. Earth Sci., 98 (4), 791805.
ROMAGNOLI C. & GABBIANELLI G. (1990) – Late quaternary
sedimentation and soft-sediment deformation features in the
Corigliano Basin, north Ionian sea (Mediterranean).
Giornale di Geologia, 52 (1-2), 33-53.
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© Società Geologica Italiana, Roma 2012
Processes of formation and evolution of submarine canyons on the
western margin of the Ligurian margin
COSTE M. (*,**), MIGEON S., (**) & CERAMICOLA S. (*)
Key words: Bathymetry, Ligurian margin, Submarine canyons,
Regressive erosion, Seismic profiles, Side‐scan sonar system,
Slope failure.
INTRODUCTION
Sediment transfer from the continental shelf to the deep
basin is of great interest as it partially controls the morphological
and architectural evolution of continental margins. Transfer of
particles on the continental slope associates with processes of
erosion and deposition that control the construction of typical
features such as submarine canyons. Because they strongly erode
the continental slope, canyons contribute significantly to its
morphological evolution through time. Canyon heads, which
have generally amphitheatre‐like morphologies, commonly incise
into the continental shelf and connect directly or indirectly with
subaerial river systems. However, a number of studies have
evidenced submarine canyons that do not connect with sub‐aerial
channelized systems, questioning their processes of formation
and evolution.
This study aims to better understand the processes of
formation and evolution of 6 submarine canyons identified on the
western margin of the Ligurian Basin, along an offshore area
extending from Nice (France) to Imperia (Italy). Processes of
slope failure are analyzed in the same zone in order to investigate
a wider range of sediment gravitytransfer processes. From
morphometric and structural analyses based respectively on
bathymetric and seismic‐reflexion (24‐channel profiles) data
acquired during the MALISAR 1 and 2 surveys, we constrained
the main geometric characteristics of canyons and failure scars
(width, depth, incision shape); and we analyzed their internal
structure in order to better understand their origin, construction
_________________________
(*) OGS (Istituto di Oceanografia e di Geofisica Spreimentale) (Borgo
Grotta Gigante, 42/c 34010 Sgonico (TS) Italia)
(**) GéoAzur (villefranche-sur-mer France) / OGS (Borgo Grotta
Gigante-Italie) (observatoire Océanologique UMR6526 GéoAzur Port de
la Darse 06235 Villefranche-sur-Mer
Fig. 1 – Structural map of the studied zone (Ligurian Margin), modified
after Courboulex et al., 1998 ; Calais et al., 2000 ; Bigot-Cormier et al.,
2004 ; Larroque et al., 2009).
mechanisms and evolution in relation with the regional
geological context.
The 6 canyons are characterized by a morpho‐structural
variability: 1/ from west to east along the studied
margin‐segment, and 1/ from the top to the base of the
continental slope. In the context of moderate tectonics, the
construction and evolution of canyons is most likely controlled
by: 1/ the topography inherited from the messinian erosion, 2/
active faulting that extended during the plio‐quaternary, 3/
margin deformation influenced by the uplift increasing eastward,
4/ the slope gradients, and 5/ the size of sub‐aerial drainage
basins.
This work also allowed us to propose two hypotheses
for the origin of canyons: canyons connected to the sub‐aerial
river system depend directly to river sedimentary discharge,
which strongly adjust to eustatic variations; whereas
slope‐confined canyons, disconnected from the shelf and river
systems, result from regressive erosion related to repetitive
small‐scale failures at their head.
We demonstrated that submarine canyons adjust to the
general evolution of the margin topography. Processes of
adjustment include for instance regressive erosion and deviation
of the thalweg axis. Canyons can therefore be used as markers of
the margin deformation in the Ligurian Basin.
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Fig. 2 – Bathymetry of the studied zone and localization of seismic profiles, and planform pattern and internal architecture of two very different canyons, the
western Var canyon and the eastern Verde canyon, the 3D diagram of the paleo-messinian surface mapped with seismic interpretation and table summarizing the
canyons morpho-structural characteristics.
REFERENCES
BETHOUX N., TRIC E., CHERY J. & BESLIER M. O. (2008) – Why
is the Ligurian Basin (Mediterranean Sea) seismogenic ?
Thermomechanical modelling of a reactivated passive
margin.
Tectonics,
27
TC5011,
16,
doi:10.1029/2007TC002232.
BIGOT-CORMIER F., SAGE F., SOSSON M., DEVERCHERE J.,
FERRANDINI M., GUENNOC P., POPOFF M. & STEPHAN J. F.
(2004) – Déformations Pliocènes de la marge nord-Ligure
(France): Les conséquences d’un chevauchement crustal
sudalpin. Bull. Soc. Géol. Fr., 175, 197-211.
MIGEON S., MULDER T., SAVOYE B. & SAGE F. (2006) – The Var
turbidite system (Ligurian Sea, northwestern Mediterranean)
Morphology, sediment supply, construction of turbidite levee
and sediment waves: Implication for hydrocarbon reservoirs.
Geo-Marine Letters., 26, 361-371.
MIGEON S., MULDER T., SAVOYE B. & SAGE F. (2012) –
Hydrodynamic processes, velocity structure and stratification
in natural turbidity currents: Results inferred from field data
in the Var Turbidite System. Sedimentary Geology,
doi:10.1016/j.sedgeo.2011.12.007.
COSTE M., MIGEON S., CERAMICOLA S., MASCLE J., FORLIN E. &
PRAEG D. (2010) – Processus de formation et d’évolution des
canyons sous-marins sur la marge oust du Bassin Ligure.
23ème Réunion des Sciences de la Terre (RST), 25-29
octobre 2010, Bordeaux, France. Abstract Poster n°160, 2ème
Prix du concours du meilleur poster. In : Livre des Résumés,
73-74.
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Rend. Online Soc. Geol. It., Vol. 21 (2012), pp. 959-961, 2 figs.
© Società Geologica Italiana, Roma 2012
Composition and depositional architecture of late Quaternary
sediments in the deep-water northern Ionian Basin, southern Italy
SALVATORE CRITELLI (*), ROCCO DOMINICI (*), FRANCESCO MUTO (*), FRANCESCO PERRI (*) &
VINCENZO TRIPODI (*)
Keywords: composition, detrital modes, fluvial systems, Ionian
Basin, northern Calabria, provenance.
INTRODUCTION
The Calabrian continental margin lies at the SE tip of the
arcuate Apennine–Maghrebide accretionary system (e.g.
SARTORI, 2003). The structural setting of this area is the result
of an interplay between the south-eastward migration of the
Calabria–Peloritani Arc since the late Miocene and the rapid
uplift of onshore and shallow shelf areas since the middle
Pleistocene. The Calabria–Peloritani Arc migra-tion resulted in
a strong dissection along several NW-trending regional shearzones, characterized by left lateral movement in the central and
northern parts and right-lateral movement in the south (KNOTT
& TURCO, 1991).
The sedimentary fill of basins is related to several factors
concerning relationships between source areas and sedimentary
basins.
This study provides insight into the petrology of modern
marine sediments, based upon the coupling of both climatic
and physio-graphic controls. Furthermore, the chemical and
mineralogical varia-tions provide additional constraints on the
behavior of the element distribution during the continental
weathering. Knowledge of such coupling is important for the
interpretation of analogous clastic deposits in the geological
record.
Italy. Two seabed structural settings can be recognized here,
the southern Apennine fold-and-thrust belt in the north and the
Crotone and Spartivento fore-arc basins in the south.
In the northern part of the study area, the Crati River and
some minor streams (Trionto, Nicà and Lipuda) feed several
wedge-top basins (e.g. Amendolara and Corigliano basins)
separated by E–Wand NW–SE trending structural ridges (e.g.
Amendolara Ridge and Rossano–Cariati High).
In the southern area the Neto and Esaro Rivers are the most
important drainage basin that feed into the Ionian deep Basin
through the Neto and Esaro Canyons separated by Hera
Lacinia–Luna High.
GEOLOGICAL SETTING
The structural setting of the study area (Fig.1) is the result
of an interplay between the south-eastward migration of the
Calabria–Peloritani Arc since the late Miocene and the rapid
uplift of onshore and shallow shelf areas since the middle
Pleistocene.
The present northern Ionian Calabrian Basin is a wedge-top
basin within the modern foreland-basin system of southern
_________________________
(*) Dipartimento di Scienze della Terra, Università della Calabria, 87036
Arcavacata di Rende (CS) – e.mail: [email protected]
Fig. 1-General sketch map of the investigated area in the Gulf of Taranto.
COMPOSITIONAL AND DEPOSITIONAL FEATURES
The exploration of the seafloor during the last three decades
has illustrated the widespread occurrence of submarine
depositional systems.
Alluvional/fluvial and deltaic systems of the Ionian side of
northern Calabria generate dominantly quartzofeldspathic sand,
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Neto River and delta; local contributions are from quartzolithic
sand of the Lipuda and Nicà Rivers, or from carbonate sand of
local intrabasinal highs and eroded late Quaternary terraces, at
the southern end of the studied area (e.g., PERRI et alii, 2012).
DISCUSSION AND CONCLUDING REMARKS
Fig. 2-Ternary plots for the sand studied samples. Qm (monocrystalline
quartz), F (feldspars) and Lt (aphanitic lithic fragments); Qm
(monocrystalline quartz), F (K-feldspar) and Fp (plagioclase); Rg (plutonic
rock fragments), Rs (sedimentary rock/lithic fragments) and Rm
(metamorphic rock fragments); Lm (metamorphic), Lv (volcanic) and Ls
(sedimentary) lithic fragments. See the text for more details.
reflecting the dominantly plutoniclastic and metamorphiclastic
nature of the key source massif of the area, the Sila Mountains.
Other local sources are the south-eastern flank of the
Southern Apennines and Neogene sequences of the Peri-Ionian
piedmont.
Sediment composition, mud geochemistry and mineralogy
identifies four main source areas for late Quaternary turbidites
of the Ionian margin. The turbidites originate from fluvial
sources of northern Calabria and are introduced through
moderate to small canyons. Deep-marine sands of the Ionian
margin are quartzofeldspathic, which reflects the dominant
mainland sources of the Crati (northern) and Neto (southern)
rivers, with lesser contributions from small drainage systems
such as the Trionto and Nicà rivers (e.g., PERRI et alii, 2012).
The Gulf of Sibari, is sedimentologically and
compositionally dominated by the Crati Fan, a sand–mud
turbidite system represented by quartzofeldspathic sand quite
similar in composition to the mainland source of the Crati
River main-channel and its river-mouth. Local contributions to
the deep marine environment are derived from the (a) Trionto
River, generating quartzofeldspathic sand turbidites, and the
(b) intrabasinal source from the Amendolara bank, generating
intrabasinal carbonate sand. In the southern studied area,
canyons and gullies dominate morphologically, and themain
source for turbidites was the Neto River. Sand– mud turbidites
are compositionally quite similar to the quartzofeldspathic
The northern Calabria along the eastern coast provides a
favorable setting in which to study complete transects from
continental to deep-marine environments.
Petrography studies of coarse-grained fraction coupled to
chemical and mineralogical analyses of the fine-grained
fraction represent an important tool for the investigations of the
processes occurred from sediment generation on the uplands to
the final accommodation on bathyal plain.
Detrital modes of sand reflect the cumulative effects of
source rock composition, chemical weathering, hydraulic
sorting and abrasion (SUTTNER, 1974; BASU, 1985; JOHNSSON,
1993). The correlation of sand composition with weathering
intensity (BASU, 1976; SUTTNER et alii, 1981) and duration of
weathering (FRANZINELLI & POTTER, 1983; GRANTHAM &
VELBEL, 1988; JOHNSSON & STALLARD, 1989; LE PERA &
SORRISO VALVO, 2000) has long been established. The
distribution ofmajor and trace elements related to the
mineralogical composition of fine-grained sediments is a
pivotal factor to reconstruct the source-area composition and
the weathering and the diagenetic processes (e.g. CONDIE et
alii, 1992, BAULUZ et alii, 2000; PERRI et alii, 2005, 2008,
2011; MONGELLI et alii, 2006; CRITELLI et alii, 2008;
CARACCIOLO et alii, 2011). By combining the information
deduced from the evolution of the X-ray diffraction (XRD)
patterns and the elemental analyses formajor and trace
elements concentrations obtained by X-ray fluorescence
spectrometry (XRF) for the mud samples and the petrographic
studies for the sand fraction, it is possible to explain and
predict the sedimentary evolution and geological processes
affecting the studied sediments and, thus, the relationship
developed between source area and sedimentary basin.
The Ionian margin of Calabria is an exceptional area in
which sedimentation and sediment composition can be
examined in the total environmental context.
The northern studied area, the Gulf of Sibari, is
sedimentologically and compositionally dominated by the Crati
Fan, a sand–mud turbidite system represented by
quartzofeldspathic sand quite similar in composition to the
mainland source of the Crati River main-channel and its rivermouth. Local contributions to the deep marine environment are
derived from the (a) Trionto River, generating
quartzofeldspathic sand turbidites, and the (b) intrabasinal
source from the Amendolara bank, generating intrabasinal
carbonate sand.
In the southern studied area, canyons and gullies dominate
morphologically, and themain source for turbidites was the
Neto River. Sand– mud turbidites are compositionally quite
similar to the quartzofeldspathic Neto River and delta; local
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contributions are from quartzolithic sand of the Lipuda and
Nicà Rivers, or fromcarbonate sand of local intra basinal highs
and eroded late Quaternary terraces, at the southern end of the
studied area.
The Ionian Calabrian margin is a typical tectonically active
siliciclastic continentalmargin,with canyon-fed sources
supplemented by smaller scale failures coming off steep slopes
adjacent to the coastline. Identification of source areas and
flowpathways has revealed single sources for sand and mud
turbidites; nonetheless, northeastward-flowing bottom currents
may have some influence on the widespread distribution of
muddy deposits.
REFERENCES
BASU, A., 1976. Petrology of Holocene fluvial sand derived
from plutonic source rocks: implications to paleoclimatic
interpretation. J. Sed. Petrol., 46, 694–709.
BASU, A., 1985.
QUARTZ. IN: ZUFFA,
READING PROVENANCE FROM DETRITAL
G.G. (ED.), Provenance of Arenites. D.
Reidel Publishing, Boston, 231–247.
BAULUZ, B., MAYAYO, M.J., FERNANDEZ-NIETO, C.,
GONZALEZ LOPEZ, J.M., 2000. Geochemistry of Precambrian
and Paleozoic siliciclastic rocks from the Iberian Range (NE
Spain):implications for source-area weathering, sorting,
provenance, and tectonic setting. Chem. Geol., 168, 135–150.
CARACCIOLO, L., LE PERA, E., MUTO, F., PERRI, F., 2011.
Sandstone petrology and mudstone geochemistry of the Peruc–
Korycany Formation (Bohemian Cretaceous Basin, Czech
Republic). Int. Geol. Rev., 53, 1003–1031.
CONDIE, K.C., NOLL, P.D.J., CONWAY, C.M., 1992.
Geochemical and detrital mode evidence for two sources of
early Proterozoic sedimentary rocks from the Tonto Basin
Super group, central Arizona. Sed. Geol., 77, 51–76.
CRITELLI, S., MONGELLI, G., PERRI, F., MARTIN-ALGARRA,
A., MARTIN-MARTIN, M., PERRONE, V., DOMINICI, R.,
SONNINO, M., ZAGHLOUL, M.N., 2008. Compositional and
geochemical signatures for the sedimentary evolution of the
Middle Triassic–Lower Jurassic continental redbeds from
western-central Mediterranean Alpine chains. J. Geol., 116,
375–386.
FRANZINELLI, E., POTTER, P.E., 1983. PETROLOGY,
chemistry and texture of modern river sand, Amazon River
system. J. Geol., 91, 23–39.
GRANTHAM, J.H., VELBEL, M.A., 1988. The influence of
climate and topography on rockfragment abundance in modern
fluvial sands of the southern Blue Ridge Mountains, North
Carolina. J. Sed. Petrol., 58, 219–227.
KNOTT, S.D., TURCO, E., 1991. Late Cenozoic kinematics of
the Calabrian Arc, southern Italy. TECTONICS 10, 1164–1172.
LE PERA, E., SORRISO VALVO, M., 2000.Weathering and
morphogenesis in a Mediterranean climate, Calabria, Italy.
Geomorphology, 34, 251–270.
MONGELLI, G., CRITELLI, S., PERRI, F., SONNINO, M.,
PERRONE,V., 2006. Sedimentary recycling, provenance and
paleoweathering from chemistry and mineralogy of Mesozoic
continental redbed mudrocks, Peloritani Mountains, Southern
Italy. Geochem. J., 40, 197–209.
PERRI, F.,MONGELLI, G., SONNINO,M., CRITELLI, S.,
PERRONE, V., 2005. Chemistry andmineralogy of Mesozoic
continental redbed mudrocks from the Calabrian Arc, Southern
Italy: im plication for provenance, paleoweathering and burial
history. Atti Tic. Sci. Terra, 10, 103–106.
PERRI, F., CIRRINCIONE, R., CRITELLI, S., MAZZOLENI, P.,
PAPPALARDO, A., 2008. Clay mineral assemblages and
sandstone compositions of the Mesozoic Longobucco Group
(north-eastern Calabria): implication for burial history and
diagenetic evolution. Int. Geol. Rev., 50, 1116–1131.
PERRI, F., CRITELLI, S., MONGELLI, G., CULLERS, R.L.,
2011. Sedimentary evolution of the Mesozoic continental
redbeds using geochemical and mineralogical tools: the case
of Upper Triassic to Lowermost Jurassic M.te di Gioiosa
mudstones (Sicily, Southern Italy). Int. J. Earth Sci., 100, 1569–
1587.
PERRI, F., CRITELLI, S., DOMINICI R., MUTO F., TRIPODI V.
& CERAMICOLA S., 2011. Provenance and accommodation
pathways of late Quaternary sediments in the deep-water
northern Ionian Basin, southern Italy. Sed. Geo., (in press.).
SARTORI, R., 2003. The Tyrrhenian back arc basin and
subduction of the Ionian lithosphere. Episodes, 2683, 217–221.
SUTTNER, L.J., 1974. Sedimentary petrographic province:
an evaluation. Society of Economic Paleontologists and
Mineralogists Special Publication, 21, 75–84.
SUTTNER, L.J., BASU, A.,MACK, G.H., 1981. Climate and
the origin of quartz arenites. J. Sed. Petrol., 51, 1235–1246.
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Preliminary results of the Marlboro and SARAS surveys: Past and
present active sedimentation and tectonics in the South Alboran Sea
ELIA D’ACREMONT1-2*, CHRISTIAN GORINI1-2, BELEN ALONSO3, ABDELLAH AMMAR4, MOHAMMED EL ABBASSI4,
MARC DE BATIST5, SILVIA CERAMICOLA6, DAMIEN DO COUTO1-2, GEMMA ERCILLA3, MARC-ANDRÉ GUTSCHER7,
SYLVIE LEROY1,2, BERNARD MERCIER DE LÉPINAY8, SÉBASTIEN MIGEON1-2, BOUCHTA EL MOUMNI9, JEFFREY
POORT1-2, LAETITIA LE POURHIET1-2, ALAIN RABAUTE1-2, PASCAL LE ROY7, JEROEN SMIT1-2, ABDELILAH
TAHAYT10, GABRIEL TEURQUETY1-2, JUAN TOMAS VAZQUEZ11 AND THE MARLBORO & SARAS TEAMS
Key words: Alboran Sea, Active faults, Contourites, growthfaults, Mud volcano, seismic reflection, swath bathymetry.
The MARLBORO-1, -2 and SARAS cruises acquired mid,
high and ultra-high resolution seismic reflection and swath
bathymetry data in 2011-2012 (Actions Marges and Eurofleets
funding). Since the Tortonian the thinned continental crust and
the overlying sedimentary cover of the Alboran Sea have been
inverted due to the convergence between Eurasia and Africa.
Fig. 1 – Structural map of the Alboran Basin and surrounding areas (MartínezGarcía, et al., 2010) drawn on the multibeam bathymetry (from (Ballesteros, et
al., 2008). Black dots: ODP Leg 161 sites, large arrows direction of plate
convergence according to NUVEL-1A model (DeMets et al. 1994). AB Algerian
Basin, AIF Al Idrisi fault zone, ARF Alboran Ridge fault zone, CB Cabliers
Bank, CF Carboneras Fault, DP Djibouti Plateau, EAB East Alboran Basin, JF
Jebha Fault, MF Maro-Nerja Fault, NF Nekor Fault, PB Pytheas Bank, PF
Palomares Fault, SAB South Alboran Basin, TB Tofiño Bank, WAB. West
Alboran Basin, XB Xauen Bank, YF Yusuf fault zone. Red box: the proposed
study area.
_________________________
(1) ISTEP, UPMC Université Paris 06, France.
(2) ISTEP, CNRS-UMR7193, France.
(3) Departament de Geologia Marina, ICM, CSIC, Barcelona, Spain.
(4) Mohammed V-Agdal Univ., Rabat, Morocco.
(5) WE13, Gent University, Belgium.
(6) OGS, Trieste, Italy. (7) IUEM, UBO, UMR6538, France.
(8) CNRS-Géoazur Université de Nice-Sophia Antipolis, France.
(9) Université Abdelmalek ESSAADI, Larache, Morocco; France.
(10) CNRST, Rabat, Morocco.
(11) IEO, Malaga, Spain.
([email protected])
We infer that the deformation along the Moroccan margin has
been significant and is still ongoing. Our study area, on the
Xauen/Tofino banks, the South Alboran ridge and the Al
Hoceima area, off Morocco, shows signs of ancient and active
strike-slip and thrust-related deformation with associated massmovement deposits and contourites. Sedimentary processes and
their interaction with tectonics are inferred from stratal
geometries and isopachs.
Fig. 2 – Cruise plans for the Marlboro-1, Marlboro-2 and SARAS cruises
(R/V Côtes de la Manche TethysII, CNFC, INSU and Ramon Margalef IEO,
Eurofleets). Topography and Bathymetry from Gebco database and bathymetric
compilation (Medimap Group, et al., 2005) in the Alboran Sea. Contour interval
is 100m
In the distal margin depositional features have been affected
by tectonic events since at least the Messinian, e.g., the
contourites along the Xauen/Tofino bank and South Alboran
ridge have been extensively involved in growth-faulting. The
seismic reflection data from southern Alboran Sea bathymetric
steep slopes show numerous slides linked to active growth-faults
as well as thrusts. Tectonic inversion is recorded since the late
Tortonian with an acceleration of uplift and compression
evidenced since the Messinian. The Xauen/Tofino and Alboran
highs have a strong internal complexity showing tight folds,
thrusts, unconformities, and intruded magmatic and mud bodies
reflecting different stages and styles of deformation. Offshore Al
Hoceima Bay a network of active normal faults and strike-slip
faults have been imaged in the bathymetric and high-resolution
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seismic reflection data. Two distinct sets of faults are observed,
one set striking north-south through the Al Hoceima Bay and the
second west of Al Hoceima Cap, striking northeast-southwest.
The latter could have been responsible for the Al Hoceima
earthquakes in 1994 and 2004.
DEMETS C., GORDON R.G., ARGUS D.F. & STEIN, S. (1994) Effect of recent revisions to the geomagnetic reversal time
scale on estimate of current plate motions. Geophys. Res.
Lett., 21, 2191-2194.
MARTÍNEZ-GARCÍA P., SOTO J.I. & COMAS M.C. (2010) - Recent
structures in the Alboran Ridge and Yusuf fault zones based on
swath bathymetry and sub-bottom profiling: evidence of active
tectonics. Geo-Mar. Lett., 31, 19-36.
REFERENCES
BALLESTEROS M., RIVERA J., MUNOZ A., MUNOZ-MARTIN A.,
ACOSTA J., CARBO A. & UCHUPI, E. (2008) - Alboran Basin,
southern Spain--Part II: Neogene tectonic implications for
the orogenic float model. Mar. Pet. Geol., 25, 75-101.
MEDIMAP GROUP, LOUBRIEU, B., MASCLE, J. et al (2005) Morpho-bathymetry of the Mediterranean Sea, 2 maps at
1/2000000. CIESM/Ifremer edition.
.
963
Rend. Online Soc. Geol. It., Vol. 21 (2012), pp. 964-966, 1 fig.
© Società Geologica Italiana, Roma 2012
Recent contourites in the Alboran Sea
ERCILLA (*), JUAN (*), ESTRADA (*), CASAS (*,°), ALONSO (*), GARCÍA (*, ^^), FARRAN (*), PALOMINO (**),
VÁZQUEZ (**), LLAVE (°), HERNÁNDEZ-MOLINA (°°), MEDIALDEA (°), GORINI (+), D’ACREMONT (+), EL
MOUMNI (++), AMMAR (^), CONTOURIBER & MONTERA TEAMS
Key words: Alboran Sea,
Mediterranean water masses.
contourites,
oceanography,
INTRODUCTION
Critical reviews of the available seismic records and analyses
of CTD data in the Alboran Sea have changed the previous
interpretations about the types of deposits making up the
nearsurface sediments of the Alboran Sea. During the last 20
years many studies about sedimentation in the Alboran Sea
suggested that turbiditic fans, gravitative deposits and
hemipelagites characterized the slopes and sub-basins of the
Alboran Sea. The new results suggest the dominance of
contourites interrupted by submarine fans and sedimentary
instabilities in those physiographic domains (Fig. 1). In this
work, we’ll focus in the contourites and the water masses
responsible of their shaping.
GEOLOGICAL SETTING
The Alboran Sea, that is located in the southwesternmost
Mediterranean Sea, is about 150 km, 350 km long, has maximum
water depths of about 1800 m and can be divided into three major
morpho-structural sub-basins, the West Alboran Basin, East
Alboran Basin, and South Alboran Basin, delimited by the East
_________________________
(*) Institut de Ciències del Mar, CSIC. C.M. Group. Passeig Marítim de la
Barceloneta, 37-49. 08003, Barcelona, Spain
Alboran Ridge, a major structural high that divides the region
obliquely and conditions a complex physiography. The
physiography of the Alboran Sea consists of four physiographic
provinces: shelf (down to 100-115m) slope (575 to 1000 m),
base-of-slope (575 to 945 m), and basins (400 to 1800 m).
Physiographic domains are affected by several seamounts that
vary in nature, being composed of volcanic rocks, basement
blocks and mud diapirs. The Alboran Sea is characterized by
siliciclastic sedimentation, the rivers being the main sources
supplying terrigenous sediments. The late Pleistocene-Holocene
stratal arquitecture is typically characterized by seismic units
whose seismic facies, nature of boundaries, geometry and
distribution are variable (ALONSO & MALDONADO, 1992;
ERCILLA et alii, 1992; ERCILLA & ALONSO, 1996, ALONSO et
alii, 1999; ERCILLA et alii, 2002).
Traditionally it was said that the general present-day
circulation in the Alboran Sea is defined by three water masses:
the surficial Atlantic Water (AW) down to 150–200 m water
depth; the Levantine Intermediate Water (LIW), which extends
down to 500-600 m water depth, and the Western Mediterranean
Deep Water (WMDW) (below 500-600 m water depth) restricted
largely to the Moroccan margin and basins. A recent study by
MILLOT (2009) in the Gibraltar Strait and surroundings, has
considered a more complex structure and dynamic, becoming to
consider five Mediterranean water masses that are grouped as
light and dense water masses. In this sense, the present day
circulation consists of an alongslope displacement of the light
MWs (Winter Intermediate Water –WIW-, LIW, upperTyrrhenian Deep Water –TDW-), located along the northern
slope, and a quite motionless displacement of the dense MWs
(lower-TDW, WMDW) along the southern slope (MILLOT,
2009).
(**) Instituto Español de Oceanografía. C.M. Group. Puerto Pesquero s/n,
Fuengirola, Málaga, Spain
METHODOLOGY
(°) Instituto Geológico y Minero de España, Ríos Rosas 23, 28003, Madrid,
Spain
More than 1000 seismic profiles have been reviewed. They
were
downloaded
from
the
ICM-CSIC
(http://www.icm.csic.es/geo/gma/SurveyMaps/) and SIGEOF
(http://www.igme.es/internet/sistemas_infor/BASESINTERNET/
sigeof.htm) databases. These data comprise multi- and singlechannel seismic records offering different degrees of resolution,
from low to very high, of the nearsurface sediments. All seismic
profiles were integrated in a Kingdom Suite project.
Hundreds of CTDs have been analyzed in order to define the
(°°) Facultad de Ciencias, Universidad de Vigo, 36200-Vigo, Spain
(+) Université Pierre et Marie Curie-Paris 6. C.M. Group. 75252 Paris
cedex 05, France
(++) Université Abdelmalek ESSAADI, Doyen de la FP – Larache,
Morocco
(^) Université Mohammed V-Agdal Rabat, Morocco
This work has been developed thanks to the CONTOURIBER (REF.
CTM2005-08071-C03-02/MAR) and MONTERA (REF. CTM-14157-C0202/MAR) projects, and Action Marges Program.
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water masses circulating throughout the Alboran Sea. The CDT
information was downloaded from the Sea Data Net website
(http:// www.seadatanet.org) and the software ODV (Ocean Data
View, http://odv.awi.de) has been used for the water masses
definition. Most of the analyzed measures of the CTDs were
during the following years: 1975, 1986, 1990, 1992, 1993, 1997.
RESULTS AND DISCUSSION
The contourite features mostly comprise plastered, sheeted,
elongated separated, confined, and channel-related drifts (Fig. 1).
They have variable sizes ranging from few km to several tens of
km in length. The plastered drifts mainly characterize the
Spanish and Moroccan slopes. Both are affected by a striking
erosive terrace (up 28 km wide), between 235 and 365 m water
depth in the Spanish margin, and between 330 and 510 m in the
Moroccan margin. Toward the base of slope, this plastered drift
connects by a steep scarp to another plastered drift in the western
Spanish margin which shows a low-mound to subtabular
geometry. Plastered drifts are also locally identified on the
seamount walls. The sheeted drifts occur from about 500 m
water depth on the central Spanish base of slope and on the
Western and Southern sub-basins. These drifts display a
subtabular geometry that makes up a smooth seafloor. The
elongated separated drifts are locally identified in the
westernmost Moroccan upper and lower slope, and at the foot of
structural seamounts and diapirs, and are easily recognized by
their low to high mound geometry. The confined drifts have also
a local presence, in the surroundings of the Alboran Ridge and
between highs in the narrow passages formed by steep structural
walls. This type of drift has a striking monticular morphology.
The channel-related drift has been mapped on the floor of the
Alboran Trough, and is characterized by discontinuous and
irregular bodies of stratified facies surrounded by a seafloor
surface of high reflectivity.
In addition to the above mentioned depositional features,
several types of erosive contourite features are also characterized;
moats, terraces, steep surfaces, and furrows are identified. The
moats are mapped associated to the elongated separated drifts
and to some plastered drifts, mainly that occurring on the walls of
the structural highs. The terraces are erosive surfaces playing a
major role in shaping the plastered drift of the continental slopes.
They connect to the shelf-break and base-of-slope by narrow
steep and erosive scarps (respectively, between 100 to 235 m,
and 365 to 600 m water depth), both roughly parallel to the
margins. These scarps play a major role in shaping the transition
between the physiographic provinces. Furrows represent linear
features eroding mostly drift deposits between both margins and
the distal erosive steep scarp in the Moroccan margin, both close
to the Gibraltar Strait. Likewise, some furrows have been
mapped in the shelf-break of the Spanish margin, also close to
the Strait of Gibraltar.
The CTDs analyses give new insights into the water masses
making up the circulation model in the Alboran Sea. Our study
confirms that the five Mediterranean water masses defined
previously by Millot (2009) in the Gibraltar Strait and
surroundings occur throughout the Alboran Sea. The surficial
AW (< 36-26.2 psu; 10 ºC) mostly extends down to 100–200 m
water depth. The WIW (37-37.7 psu; 12.9-13 ºC) is defined in
Fig1.- Geomorphologic map of the Alboran Sea.
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the slope of the Spanish margin, between 100 and 300 m, and its
occurrence is not permanent. The LIW (13.1-13.2 psu; 38.5 ºC)
has been defined between 200 and 600 m, and mostly circulates
along the Spanish margin and central basin. The TDW (38.4-38.5
psu; 13ºC) shows a core not-well defined, showing similar
characteristics to the overlying LIW and underlying WMDW.
Because of that, its definition is not an easy task. It is mainly
characterized in the Spanish margin (400 to 550 m) and basin,
and locally and/or sporadically to shallower water depths ( 275 to
400 m) in the Moroccan margin. The WMDW (12.7-12 psu;
38.4-38.52 ºC) moves troughout the basin of the Alboran Sea and
Moroccan slope, and their water depths are very variable
according to the margins it sweeps, being identified below 540 m
in the Spanish margin and mostly below 300 m in the Moroccan
slope, although here it has been characterized shallower, below
180 m.
sediment distribution of the plastered and sheeted drifts in the
Moroccan slope and base-of-slope and erosive scarps. The
WMDW also would favor the shaping of the sheeted drift in the
basins and furrows. The interaction of the mentioned water
masses with highs and corridors favor the formation of elongated
separated at the break of slope, plastered on the walls, confined
and channel-related drifts in the passages and corridors.
CONCLUSIONS
ERCILLA, G. & ALONSO, B. (1996). Quaternary siliciclastic
sequence stratigraphy of western Mediterranean passive and
tectonically active margins: the role of global versus local
controlling factors. From: Geology of Siliciclastic Shelf Seas
(De Batist, M. & Jacobs, P. eds). Geological Society Special
Publication, 117, 125-137.
The recognized morphosedimentary features indicate that
contourites dominate the slope, base-of-slope and basin
sedimentary settings in the Alboran Sea.
Likewise, the
recognized water masses suggest: 1) the presence of four
Mediterranean water masses, WIW, LIW, TDW and WMDW;
their presence is unequal in the Spanish and Moroccan margins,;
2) the mentioned water masses are responsible of the contourites
deposits and features; and 3) due to the action of different water
masses shaping the margins and basins, the contourites, both
deposits and features, make up a sedimentary complex, named
the Alboran contourite sedimentary complex. The action of the
WIW and LIW is particularly marked in the Spanish margin,
being responsible of the plastered drift with erosive terrace and
scarps. The LIW and WMDW would have controlled the
REFERENCES
ALONSO, B. & MALDONADO, A. (1992). Plio-Quaternary Margin
Growth Patterns in a Complex Tectonic Setting: Northeastern
Alboran Sea. Geo-Marine Letters, 12, 137-143.
ERCILLA, G., ALONSO, B. & BARAZA, J. (1992). Sedimentary
Evolution of the Northwestern Alboran Sea during the
Quaternary. Geo-Marine Letters, 12, 144-149.
ERCILLA, G., BARAZA, J., ALONSO, B., ESTRADA, F., CASAS, D. &
FARRÁN, M. (2002). The Ceuta Drift, Alboran Sea,
southwestern Mediterranean. From: Deep-Water Contourite
Systems: Modern Drifts and Ancient Series, Seismic and
Sedimentary Characteristics (Stow, D. A. V., Pudsey, C.J.,
Howe, J.A., Faugères, J.-C. & Viana, A.R., eds). Geological
Society, London, Memoirs, 22, 155-170.
MILLOT, C. (2009). Another description of the Mediterranean Sea
outflow. Progress in Oceanography, 82, 101-124.
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Rend. Online Soc. Geol. It., Vol. 21 (2012), pp. 967-969.
© Società Geologica Italiana, Roma 2012
A Messinian analogue for the subsurface plumbing of marine oil
seeps (Maiella foreland basin, Central Apennine)
ANNALISA IADANZA (*), GIANLUCA SAMPALMIERI (*), PAOLA CIPOLLARI (*,**), DOMENICO COSENTINO (*,**),
MARCO MOLA (**)
Key words: hydrocarbon-charged fluids, Maiella
Messinian, microchimneys, neoformed channels.
basin,
limestone-bearing unit (the Brecciated Limestones informal unit).
THE FLUID MIGRATION PATHWAYS AND THE
BRECCIATED LIMESTONES IN THE MAIELLA BASIN
INTRODUCTION
Processes of hydrocarbon-charged fluid migration and the
related products have been increasingly reported in the geological
literature both in present-day and ancient settings (HOVLAND et
alii, 1987; CAMPBELL et alii, 2002; CAMPBELL, 2006; HUUSE et
alii, 2010). The major seep-related features revealed in active or
subrecent settings include: mud volcanoes, pockmarks,
authigenic seep carbonates, chimneys, gas hydrates and cold seep
communities (KOPF, 2002; JUDD & HOVLAND, 2007). The
precipitation of authigenic carbonates takes place at hydrocarbon
seeps as a result of the increase in alkalinity produced by the
release of HCO3- during the anaerobic oxidation of methane
(AOM) and higher hydrocarbons (RITGER et alii, 1987; PAULL et
alii, 1992). The identification of palaeo-cold seeps is chiefly
inferred by the occurrence of δ13C-depleted seep limestones
(concretions and slabs) and cemented chimneys, interpreted to
act as fluid migration pathways.
If compared to the extensively reported seafloor examples (e.g.
CAMPBELL et alii, 2002; PECKMANN et alii, 2002; MAZZINI et
alii, 2003; SCHWARTZ et alii, 2003; CONTI et et alii, 2004, CONTI
& FONTANA, 2005; HOVLAND et alii, 2005; GAY et alii, 2006 a,b;
CAMPBELL et alii, 2008), the subsurface counterparts of
hydrocarbon seeps are poorly documented, even in
correspondence to the easily accessible points offered by
outcrops of palaeoseeps (AIELLO et alii, 2001; CLARI et alii,
2004; DE BOEVER et alii, 2006; CLARI et alii, 2009; NYMAN et
alii, 2010).
The Messinian succession of the Maiella foreland basin
(Abruzzo, Central Apennines) offers an interesting example of a
seep plumbing system: fluid migration pathways occur at
different scales and are associated to an extensively brecciated
_________________________
(*) Dipartimento di Scienze Geologiche, Università degli Studi Roma Tre
([email protected])
(**) Istituto di Geologia Ambientale e Geoingegneria (IGAG-CNR), Area
della Ricerca Roma 1, Montelibretti
The Brecciated Limestones of the Maiella Basin belong to the
early post-evaporitic phase of the Messinian Salinity Crisis
(MSC) of the Mediterranean Basin: they overlay the Lower
Evaporites through the well known regional unconformity
(Messinian Erosional Surface, MES).
In this study the field work was addressed to the detection and
the typification of structures referable to channelways and to the
identification of main facies associated to them.
Sedimentological and fabric observations, performed with optical
and electronic microscopic devices, were integrated with stable
isotopes analyses (δ18O and δ13C).
The Brecciated Limestones mostly consist of widely brecciated
carbonate buildups and minor concretions laterally embedded or
passing to an anoxic host sediment (marly-pelitic fraction). Tar
plugs, brown concretioned patches and minor pelites trapped in
are at places associated to the main geobodies. The massively or
broadly stratified limestones, brecciated and cemented to
different degrees, are accompanied by both mesoscale
channelways and micro-chimneys collected
from the
surrounding sediment.
The major fluid migration pathways are extremely localized.
The channels attain even several meters in height in outcrop,
cutting the MSC-related stratigraphic succession at different
levels. They show irregular but sharp pipe walls, often
accompanied by secondary tortuous fluid channels, branching out
laterally, and mushroom-like tops. According to the glossary
proposed by DIÁZ-DEL-RÍO et alii (2003), the chimneys are
generally mounded, with bended trajectories and lateral auxiliary
vent orifices. Dark brown, finely contorted and wispymicrofolded pelites with subordinate carbonate concretions
constitute the main facies association. Beside the concretions,
secondary carbonatic components are represented by fibrous
aragonitic fans and vuggy scoria-like limestones.
Micro-scale fluid channels were also observed in thin section,
in terms of extremely fluidal textures and locally microbrecciated
microbialite. Furthermore, collected from the barren host
sediment, hollow cylindrical carbonate precipitates occur,
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86° CONGRESSO SOCIETÀ GEOLOGICA ITALIANA
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inferred to represent micropipes on the basis of their depletion in
δ13C and their strikingly resemblance to (sub)recent counterparts
(PECKMANN et alii, 2001, 2005; JONES et alii, 2009). From a
morphological point of view, they are cylindrical and typified by
broadly circular cross-sections, displaying a variety of enigmatic
morphologies (single, double, bifurcated, dumb-bell shaped or
even multiple composite microtubes).
Together with the fluid migration features detected at any scale
(outcrop-scale pathways, microchimneys, fluidal microtextures),
a number of seep settings markers were also encountered: 1) at
the mesoscale: patchiness and knotted fabrics, widespread
brecciation; 2) at the microscale: tar impregnations, framboidal
pyrite, celestite and barite, botryoidal aragonite; 3) in the
geochemical dataset: wide ranges of negative δ13C data.
The detection of tar-bearing facies and the geochemical dataset in
fact, showing wide ranges both in δ18O (~ +5 down to -10 ‰
PDB) and δ13C values (~ +5 down to -40 ‰ PDB), point to fluids
charged by hydrocarbons, at least to some extent.
Interstingly, two end members in the carbon stable isotopes
record are represented by: a) the carbonates yielding the less
depleted δ13C values, associated to the mesoscale fluid migration
pathways and to higher brecciation degrees, pointing to focused
fluid flow with high flux rates and subsequent low fluid-rock
interaction (AOM secondarily involved in authigenesis); b) the
most δ13C-depleted carbonates, i.e. chaoticized patchy
limestones associated to the host sediment, the microchimneys
and the carbonates yielding lower brecciation degrees, testifying
the occurrence of pervasive fluid flow, low flux rates (seepage)
and subsequent high fluid-rock interaction (AOM directly
involved in authigenesis).
Similar phenomena are known also from modern counterparts,
where hydrocarbon emissions, for instance, range from slow and
diffuse - forming seep-carbonates - to fast and vigorous,
developing chimneys and mud volcanoes (RITGER et alii, 1987;
AHARON, 1994).
CONCLUSIONS
The presumable origin of the Brecciated Limestones of the
Maiella Basin from the subsurface, within the sedimentary
column, is inferred by the occurrence of widespread
autobrecciation accompanied by fluid channels, together with the
absence of chemosynthesis-based paleocommunities. In view of
that, the Brecciated Limestones of the Maiella Basin, with their
fluid migration pathways and microchimneys, are interpreted to
represent possible vestiges of a mud volcano feeder system. The
proposed scenario for the late Messinian Maiella Basin depicts an
upward hydrocarbon-rich fluid migration through the Messinian
succession, developed with major fluxes along giant neoformed
channels and seepage through the host sediment via cemented
microchimneys. In the upper Miocene of Italy, a similar case is
known from the Tertiary Piedmont Basin (NW Italy) (CLARI et
alii, 2009; MARTIRE et alii, 2010; DELA PIERRE et alii, 2010).
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AIELLO I.W., GARRISON R.E., MOORE J.C., KASTNER M. &
STAKES D.S. (2001) - Anatomy and origin of carbonate
structures in a Miocene cold-seep field. Geology, 29, 1111–
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CAMPBELL K. A. (2006) - Hydrocarbon seep and hydrothermal
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CAMPBELL K.A., FRANCIS D.A., COLLINS M., GREGORY M.R.,
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Coast Basin), North Island, New Zealand. Sedimentary
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FIORONI C. & FREGNI P. (2004) - A multidisciplinary study of
middle Miocene seep-carbonates from the northern Apennine
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-FRIAS J., MATA M.P.,
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the past occurrence of gas hydrates in the sediment column.
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HURST A. (2003) - Fluid escape from reservoirs: implications
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tubular concretions in East Coast Basin, New Zealand:
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PAULL C.K., CHANTON J.P., NEUMANN A. C., COSTON J.A.,
MARTENS C.S., SHOWER W. (1992) - Indicators of methanederived carbonates and chemosynthetic organic carbon
deposits: examples from the Florida Escarpment. Palaios, 7,
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© Società Geologica Italiana, Roma 2012
The Plio-Quaternary stratigraphy in the Eastern Alboran Sea
JUAN (*), ERCILLA (*), ESTRADA (*), CASAS (*,°), ALONSO (*), GARCÍA (*, ^^), FARRAN (*), PALOMINO (**),
VÁZQUEZ (**), LLAVE (°), HERNÁNDEZ-MOLINA (°°), MEDIALDEA (°), GORINI (+), D’ACREMONT (+), EL
MOUMNI (++), AMMAR (^), CONTOURIBER & MONTERA TEAMS
Key words: Alboran Sea, contourites, paleoceanography, PlioQuaternary, stratigraphy.
INTRODUCTION
The Alboran Sea is a Neogene extensional basin developed in
a convergence tectonic setting that generates a complex
physiography. The SW-NE-trending Alboran Ridge separates
three main basins, Western, Eastern and Southern.
The filling of the Alboran Basin is composed of Early
Miocene to Quaternary deposits (CAMPILLO et alii, 1992). The
Plio-Quaternary deposits lies over a strongly erosive surface (the
Messininan surface -M reflector-) with three major types of
features: the Zanclean Channel, several terraces, and canyons
(ESTRADA et alii, 2011). The Plio-Quaternary sedimentary
evolution has been controlled mainly by the interplay of
tectonics, sea-level changes, and a complex ocean circulation
(ERCILLA et alii, 1994).
Most of the geological studies done since the 80’s in the
Alboran Sea suggested that downslope processes were dominant,
(ERCILLA et alii, 1992). Locally, contourite features had been
defined in the westernmost slope of the Moroccan margin
(ERCILLA et alii, 2002).
Critical reviews of the available seismic records and of our
previous
literature
allowed
us
re-interpreting
the
_________________________
morphosedimentary features that characterize the Alboran Sea.
We propose the dominance of alongslope processes in the
Alboran Sea, that are locally modified by the downslope
processes at the margins, submarine fans, and walls of the
Alboran Ridge and seamounts.
RESULTS AND DISCUSSION
Recently we defined and correlated three new
chronostratigraphic limits at the Western Alboran Sea (JUAN et
al., 2012): Lower Pliocene Revolution –LPR- (4.2 M.a.) related
to a 3rd order global sea-level fall, Base of Quaternary
Discontinuity –BQD- (2.6 M.a.) also related to a major sea-level
fall and an important change in the climatic cyclicity trend, and
Middle Pleistocene Revolution –MPR- (0.92 M.a.) that marks the
onset of the first major glaciations in the northern hemisphere
and a shift to large amplitude (100 k.y.) and asymmetric climatic
cycles. The addition of these boundaries, with paleoclimatic and
paleoceanographic significances, is a key change in the Alboran
stratigraphy, since the purpose of the present work is to analyze
the climate-driven paleocirculation patterns. In order to correlate
the different stratigraphic divisions and limits, we summarized
the most relevant stratigraphies in Table I.
Based only on these paleoclimatic and paleoceanographic
boundaries we have divided the Plio-Quaternary sedimentary
register into four major seismic units: A to D, from older to
younger.
(*) Institut de Ciències del Mar, CSIC. C.M. Group. Passeig Marítim de la
Barceloneta, 37-49. 08003, Barcelona, Spain
Unit A (Early Lower Pliocene)
(**) Instituto Español de Oceanografía. C.M. Group. Puerto Pesquero s/n,
Fuengirola, Málaga, Spain
This unit is bounded by M and LPR discontinuities (Table I).
The M limit (i.e., the Messinian surface) is a strong, laterally
continuous erosive boundary. The LPR shows low acoustic
amplitude. The lower M limit shows onlap reflection
terminations on the structural highs, and the upper LPR limit
shows a local erosive character. At the Eastern Alboran Basin
this unit drapes and infills the irregular paleoreliefs showing
variable thickness (0 to 275 ms). This unit comprises mainly
deposits characterized by low reflectivity discontinuous stratified
facies (Fig. 1), locally affected by slope apron facies. The seismic
facies have been interpreted as an extensive sheeted drift
covering most of the basin, locally affected by contouritic
channels and deformed by the regional tectonics.
(°) Instituto Geológico y Minero de España, Ríos Rosas 23, 28003, Madrid,
Spain
(°°) Facultad de Ciencias, Universidad de Vigo, 36200-Vigo, Spain
(+) Université Pierre et Marie Curie-Paris 6. C.M. Group. 75252 Paris
cedex 05, France
(++) Université Abdelmalek ESSAADI, Doyen de la FP – Larache,
Morocco
(^) Université Mohammed V-Agdal Rabat, Morocco
This work has been developed thanks to the CONTOURIBER (REF.
CTM2005-08071-C03-02/MAR) and MONTERA (REF. CTM-14157-C0202/MAR) projects, and Action Marges Program.
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Unit B (Late Lower to Upper Pliocene)
the turbiditic lobes of the Almeria TS, with interbedded reflectors
showing high to very high acoustic response.
This unit is bounded by LPR limit at the base and BQD limit
at top. The BQD boundary shows medium to high acoustic
amplitude and locally the top of the unit is eroded. Deposits of
this unit even drape structural highs, onlapping at the flanks. The
unit shows great thickness, reaching 750 ms near the Alboran
Through. Deposits are characterized by a vertical change from
low to high acoustic amplitude and show an aggradational
pattern. Contourite features as sheeted, plastered and elongated
separated drifts have been defined both at the slopes and the
basin, showing strong influence of tectonic activity.
Unit D (Middle toUpper Quaternary)
The last unit is bounded by the MPR limit at base, and by the
seafloor at top. These boundaries are mostly concordant surfaces.
The depocenters are located in the Almeria Fan (250 ms), and
near the Alboran Through (250 ms). This unit is characterized by
an aggradational pattern (Fig. 1). Sheeted and plastered contourite
deposits are common at the slope and structural highs, and we
find again sheeted drift facies mixed with the distal turbiditic
lobes to the south of the basin.
Unit C (Lower Quaternary)
This unit is bounded by the BQD limit at bottom and the MPR
limit at top. Its lower boundary is generally a concordant surface.
The MPR limit shows medium to high acoustic amplitude and is
an erosive surface. The maximum depocenter is located to the
north (300 ms). Acoustically, deposits are defined by stratified
facies of high acoustic amplitude and chaotic facies. This unit is
mostly made up of plastered and sheeted drifts at the slopes and
structural highs, showing stratified facies with high acoustic
response . The lateral continuity of these deposits is interrupted by
CONCLUSIONS
The definition and correlation of the new chronostratigraphic
boundaries, named LPR, BQD and MPR, has allowed defining a
new Plio-Quaternary sedimentary model for the Alboran Sea. In
fact, this new stratigraphy has highlighted the effects of the
Mediterranean water masses, and the role played by the
contourites, deposits and features, in the outbuilding of the
Spanish and Moroccan margins and basin infilling.
TABLE 1
Correlation of the most relevant Plio-Quaternary stratigraphies at the Alboran Sea area.
Q-II
Pérez-Belzuz,
1999
HernándezMolina et al.,
2002
Ct3
Campillo et al.,
1992
Pérez-Belzuz,
1999
Subunit la
Pérez-Belzuz et
al., 1997
Jurado and
Comas, 1992
Seq.
1
Bibliographic discontinuities
Other
D
Tarantian (Upper )
Ionian (Middle)
MPR
Calabrian (Lower)
C
Seq.
2
Gelasian (Lower)
Piacenzian (Late)
BQD
B
Pliocene
Zanclean (Early)
A
LPR
M
Seq.
3
Seq.
4
Ia
Ct2
Ib
Ct1
Pl3
Subunit lb
Holocene
Pleistocene
Bibliographic Stratigraphies
Campillo et al.,
1992
Stage
Age
Seismic
boundaries
Series
Epoch
Units
Stratigraphy
in this study
971
Ic
Id
Pl2
Pl1
Q1
Q2
B
Q-1
P2
P3
P2-II
P2-I
M/P1
A
(HernándezMolina et al.,
2002) MPR
(HernándezMolina et al.,
2002) UPR
P1
(Ryan et al.,
1973) M
86° CONGRESSO SOCIETÀ GEOLOGICA ITALIANA
18-20 SETTEMBRE 2012, ARCAVACATA DI RENDE (CS)
REFERENCES
CAMPILLO, A.C., MALDONADO, A. & MAUFFRET, A. (1992).
Stratigraphic and Tectonic Evolution of the Western Alboran
Sea: Late Miocene to Recent. Geo-Marine Letters, 12, 165172.
ERCILLA, G., ALONSO, B. & BARAZA, J. (1994). Post-Calabrian
sequence stratigraphy of the northwestern Alboran Sea
(southwestern Mediterranean). Marine Geology, 120, 249265.
ERCILLA, G., BARAZA, J., ALONSO, B., ESTRADA, F., CASAS, D., &
FARRÁN, M. (2002). The Ceuta Drift, Alboran Sea,
southwestern Mediterranean. From: Deep-Water Contourite
Systems: Modern Drifts and Ancient Series, Seismic and
Sedimentary Characteristics (STOW, D. A. V., PUDSEY, C.J.,
HOWE, J.A., FAUGÈRES, J.-C. & VIANA, A.R., eds). Geological
Society, London, Memoirs, 22, 155-170.
ESTRADA, F., ERCILLA, G., GORINI, CH., ALONSO, B., VÁZQUEZ,
J.T., GARCÍA-CASTELLANOS, D., JUAN, C., MALDONADO, A.,
AMMAR, A. & ELABBASSI, M. (2011). Impact of pulsed
Atlantic water inflow into the Alboran Basin at the time of the
Zanclean flooding. Geo-Marine Letters, 31, 361-376.
HERNÁNDEZ-MOLINA, F.J., SOMOZA, L., VÁZQUEZ, J.T., LOBO,
F., FERNÁNDEZ-PUGA, M.C., LLAVE, E., & DÍAZ-DEL RÍO, V.
(2002). Quaternary stratigraphic stacking patterns on the
continental shelves of the southern Iberian Peninsula: their
relationship with global climate and palaeoceanographic
changes. Quaternary International, 92, 5-23.
JUAN, C., ERCILLA, G., ESTRADA, F., CASAS, D., ALONSO, B.,
GARCÍA, M., FARRAN, M., PALOMINO, D., VÁZQUEZ, J.T.,
LLAVE, E., HERNÁNDEZ-MOLINA, F.J., MEDIALDEA, T.,
GORINI, C., D’ACREMONT, E., EL MOUMNI, B., GENSOUS, B.,
TESSON, M., MALDONADO, A., AMMAR, A., CONTOURIBER &
MONTERA TEAMS (2012). Contourite sedimentation in the
Alboran Sea: Plio-Quaternary evolution. VIII Geological
Society of Spain Congress, Book of Abstracts.
JURADO, M.J. & COMAS, M.C. (1992). Well Log Interpretation
and Seismic Character of the Cenozoic Sequence in the
Northern Alboran Sea. Geo-Marine Letters, 12, 129-136.
PÉREZ-BELZUZ, F., ALONSO, B., & ERCILLA, G. (1997). History
of mud diapirism and trigger mechanisms in the Western
Alboran Sea. Tectonophysics, 282, 399-422.
PÉREZ-BELZUZ, F. (1999). Geología del Margen y Cuenca del
mar de Alborán durante el Plio-Quaternario: Sedimentación
y Tectónica. Tesis Doctoral, Univ. de Barcelona, 554 p.
Fig. 1 – A) Single-channel seismic profile and line drawing at the central
Western Alboran Basin showing respectively: A) the major stratigraphic
boundaries with paleoceanographic and paleoclimatic meanings (italic) and
sedimentary units (bold), and B) grayscale scheme of the main stratigraphic
boundaries (italic) and sedimentary units (bold).
RYAN, W.B.F., HSÜ, K.J., CITA, M.B., DUMITRICA, P., LORT, J.,
MAYNE, W., NESTEROFF, W.D., PAUTOT, G., STRADNER, H.,
& WEZEL, F.C. (1973). Western Alboran Basin - Site 121.
From: Initial Reports of the Deep Sea Drilling Project
(RYAN W.B.F., HSÜ, K.J., and others, eds.), 13, 43-89.
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© Società Geologica Italiana, Roma 2012
Active mud volcanism and seabed seepage on the Calabrian
accretionary prism, Ionian Sea
D. PRAEG (*1), S. CERAMICOLA (1), C. PIERRE (2), J. MASCLE (3), S. DUPRÉ (4), A. ANDERSEN (5), L. CAMERA (3),
A. COVA (1), G. DE LANGE (6), E. DUCASSOU (7), A. FREIWALD (8), F. HARMEGNIES (4), D. HEBBELN (9), L.
LONCKE (10), V. MASTALERZ (6), S. MIGEON (4), M. TAVIANI (11)
Key words: mud volcanoes, fluid seepage, gas, ecosystems.
ABSTRACT
Multidisciplinary investigations of submarine mud volcanoes
on the Calabrian accretionary prism led by OGS provide
evidence of late to post-glacial eruptive activity, and of ongoing
seabed seepage that supports ‘hotspot’ ecosystems. Data were
acquired from two structures, the Madonna dello Ionio and
Pythagoras mud volcanoes (MVs), in water depths of 1600-2300
m (Fig. 1), using geophysical methods (multibeam, seismic),
cores and remotely-operated vehicles (ROVs), during campaigns
of Italian, German and French research vessels. The two sites
include a variety of positive and negative morphologies (cones,
caldera, broad dome – Fig. 2), all associated with high seabed
backscatter, consistent with relatively recent extrusive activity;
this is confirmed by gravity cores that recovered mud breccias
near seabed. Dating of overlying sediments at one site (Madonna
MVs) indicates at least one extrusive episode since the last
glacial maximum (c. 20 ka). At both sites, bottom water samples
obtained using ROVs indicate seepage of gas to the water
column. At the Madonna MVs, evidence of seabed fluid seepage
is also provided by: a) elevated geothermal gradients at three
extrusive centers; b) localized outflows of warm mud; and c)
chemosynthetic ecosystems. At the Pythagoras MV, such
indications are absent, but ROV investigations reveal an area of
chaotic seabed suggestive of a recent, violent eruptive episode.
The ongoing activity of the mud volcanoes may reflect either
long-term tectonic drivers, or climate-driven post-glacial
destabilization of gas hydrate that are theoretically stable at both
structures.
_________________________
(1) Istituto Nazionale di Oceanografia e di Geofisica Sperimentale,
34010, Trieste, ITALY - *[email protected]
(2) LOCEAN, Université Pierre et Marie Curie, Paris, FRANCE
(3) Géosciences Azur, Villefranche sur Mer, FRANCE
(4) IFREMER, Centre de Brest, FRANCE
(5) Station Biologique de Roscoff, FRANCE
(6) Utrecht University, 3508 TC Utrecht, Netherlands
(7) Université Bordeaux, FRANCE
(8) Universität Erlangen-Nürnberg, GERMANY
(9) Universität Bremen, GERMANY
(10) Université de Perpignan, FRANCE
Fig. 1 – Locations of the two investigated mud volcanic structures on the
Calabrian Arc: A Madonna dello Ionio MVs, B Pythagoras MV.
(11) CNR ISMAR, Bologna, 40129, Italy
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Fig. 2 – Locations of ROV dive tracks across the two investigated mud volcano structures (A and B in Figure 1). The Madonna dello Ionio mud volcanoes
include twin cones c. 140 m high and a caldera including a central elevation to the north; the Pythagoras mud volcano is a broad mud dome or pie.
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Rend. Online Soc. Geol. It., Vol. 21 (2012), pp. 975-977, 2 figs.
© Società Geologica Italiana, Roma 2012
Petrographical and mineralogical characterization of marine
sediments in the mud diapir province of the Paola Basin (Southern
Tyrrhenian Sea)
HEBA RASHED (*), MARZIA ROVERE (**), ELENA PECCHIONI(*), FABIANO GAMBERI (**), ORLANDO VASELLI (*,***),
GABRIELE BICOCCHI (*), FRANCO TASSI (*,***)
Key words: Geochemistry, Mineralogy, Paola Basin, Plio-
Quaternary sediments, South Tyrrhenian Sea.
of gas emissions at the seafloor through the analysis of the gasrelated products.
INTRODUCTION
The study area is located within the Paola Basin along the
southeastern margin of the Tyrrhenian Sea. The geodynamic
evolution of the Paola Basin is related to the extensional
tectonics that led to the opening of the Tyrrhenian Sea. The
basin is characterized by a thick Plio-Quaternary sedimentary
sequence, whose origin is likely related to turbiditic currents
(TRINCARDI et alii, 1995). The study area is bounded by a calc–
alkaline volcanic complex (Alcione and Lametini) to the west,
while to east is bordered by a system of normal faults that
separate it from the Coastal Range in Calabria (Fig. 1). The
Paola Basin hosts a 60-km-long NNW-SSE oriented prominent
anticline, the Paola Ridge, interpreted to be the result of an
episode of early Pleistocene compression (ARGNANI &
TRINCARDI, 1988). A more recent interpretation defines the
Paola Ridge as due to a mobile mud belt connected with a set of
extensional faults trending NW-SE to NNW-SSE (GAMBERI &
ROVERE, 2010). With the aim of proving this latter
interpretation, the MVP11 oceanographic cruise was carried out
in August-September 2011 on board the R/V CNR URANIA,
during which very high resolution swath bathymetry and
shallow seismic data were collected plus 30 gravity coring sites
and 30 box-cores stations were performed in order to define the
petrographical, mineralogical and geochemical composition of
the cored sediments and the collected rock samples (Fig. 2).
This study is part of a PhD fellowship carried out in
collaboration with the Department of Earth Sciences of
Florence and the CNR-ISMAR (Institute of Marine Sciences) of
Bologna (Italy) and aimed to: i) define the mineralogical and
geochemical characteristics of marine sediments related to mud
diapirism sampled in the study area and ii) verify the presence
Fig. 1- Bathymetry of the southeastern Tyrrhenian Sea, Paola Basin. The
study area is enclosed in the box that corresponds to the area of Fig. 2,
where sampling sites are enlightened. From Gamberi & Rovere (2010).
MATERIALS AND METHODS
For this work we have analyzed different kind of samples
(rocks/sediment):
a)
limestone crusts cored along faults dissecting mud diapir
structures; authigenic carbonates retrieved from the core
catcher of stations performed over mud volcanoes and
their downslope mudflows;
b) iron oxy-hydroxide crusts found in the box cores stations
on top of the mud volcanoes structures, where strong gas
emissions were recognized by water column multi-beam
records and direct sampling;
c) flat crusts of pyrite and sulfur retrieved in the upper
section of the cores and in the box cores performed on
top of the mud volcanoes;
d) cohesive mud sampled along the coring sections of the
most energetic mud volcanoes structures discovered in
the area.
_________________________
(*) Department of Earth Sciences – University of Florence – Via La Pira
4, 50121 Florence (Italy)
(**) CNR-ISMAR, Institute for Marine Sciences – Via P. Gobetti 101,
40129 Bologna (Italy)
(***) CNR-IGG, Institute of Geosciences and Earth Resources - Via La
Pira 4, 50121 Florence (Italy).
The sampling was carried out using a 1.2 t gravity coring
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observations have allowed to characterize different sample
types: a) fractured and porous mudstone-wackestone with the
presence of pyroxenes and rare quartz and plagioclases; b)
mudstone with rare presence of quartz; c) biomicrite with rare
presence of quartz and medium porosity.
The preliminary mineralogical analyses on the different rock
samples were used to recognize the three groups: a) carbonates
mostly containing calcite, quartz, siderite, feldspars
(plagioclase), and phyllosilicates and carbonates with calcite,
aragonite, dolomite, phyllosilicates (muscovite and clay
minerals) and pyroxene; b) sulfides mainly consisting of quartz,
pyrite and/or sphalerite, marcasite and plagioclase and traces of
phyllosilicates;
c)
iron
oxy-hydroxides
dominantly
characterized by goethite, quartz, feldspars (plagioclase) and
phyllosilicates.
The mineralogical analyses carried out on the marine
sediments (cohesive mud) have indicated the presence of
quartz, halite, feldspars (plagioclase and k-feldspar), muscovite
and clay minerals (illite, vermiculite, chlorite, kaolinite) unless
one sample where chlorite was absent; occasionally, some
samples were composed by calcite and/or dolomite, siderite,
hematite and pyrite.
Fig. 2- High resolution swath bathymetry acquired during cruise
MVP11 in the samples, MVP11-BC Box core stations, MVP11-GC
gravity coring stations, MVP11-DG dredge stations.
CONCLUSIONS
device with a penetration length between 4 and 12 m. Box cores
were collected with an oceanic box corer with a hollow metal
cylinder of 50 cm in diameter and a volume capacity of 100 L.
All the samples were dried (at 40 °C), grinded and grounded
(with a planetary agate mill device). Both sediments and rock
fragments were analyzed to determine the semi-quantitative
composition of the main mineralogical phases. In the sediments
the <4 m granulometric fraction was also separated for the
determination of the clay minerals content.
The mineralogical analyses were carried out by XRD with a
Philips PW 1050/37 diffractometer, operating at 40 kV-20 mA,
with anode a Cu, graphite monochromator at an interval 2θ of 570° e 2-32° (limit of detection 4%), using the X’Pert PRO Philips
acquisition system. Polished thin sections of rock samples were
prepared for petrographic observations by using an optical
microscopy in transmitted light for the textural characterization
of the samples and point out the presence of mineral index, using
a microscopy ZEISS Axioskop, equipped with video camera
(resolution 5 Megapixel), provided with image analysis
Axiovision.
The Paola Basin is a key area for better understanding the
evolution of the southern part of the Tyrrhenian Sea. Regional
structural studies describe the area as affected by relevant
tectonic compression, but more recent high resolution
investigations have revealed the presence of gas-related
structures, probably activated by normal faulting. Sampling data
are now available in the area. The petrographical and
mineralogical data presented in this work have allowed to
highlight important features that can be used to understand the
geochemical processes affecting the depositional environment
into which the marine sediments were deposited. In this
framework, the petrographic characterization and the
interpretation of the mineralogical composition will be related
to the active structures (mud diapirs and mud volcanoes)
recently recognized in the Paolo Basin. Furthermore, the
chemical composition of the carbonate-hosting pyroxenes may
shed light on their provenance studies, along with chemical and
isotopic investigations in both cohesive mud sediments and
pyrite and sulfur crusts that are presently in progress, the latter
to be investigated in order to comprehend the effects due to the
gas discharges.
REFERENCES
RESULTS AND DISCUSSION
The petrographic analyses by microscopy in transmitted
light were only carried out on the limestone crusts, and the
ARGNANI A. & TRINCARDI F. (1988) - Paola slope basin:
evidence of regional contraction on the eastern Tyrrhenian
margin. Mem. Soc. Geo. It., 44, 39-105.
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GAMBERI F. & ROVERE M. (2010) - Mud diapirs, mud volcanose
and fluid flow in the rear of the Calabria Arc orogenic wedge
(southeaster Tyrrenian Sea). Basin Res. 22, 452-464.
TRINCARDI F., CORREGGIARI A., FIELD M.E., & NORMARK WR.
(1995)- Turbidite deposition from multiple sources:
Quaternary Paola Basin (eastern Tyrrhanian Sea). Jour.
Sediment. Res., 65, 469-483.
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© Società Geologica Italiana, Roma 2012
Large deep-seated slump structure off Ischia volcanic island,
Eastern Tyrrhenian sea (Italy)
CRESCENZO VIOLANTE (*), GIOVANNI DE ALTERIIS (*), FABRIZIO PEPE (**) & SALVATORE MAZZOLA (*)
Key words: Ischia Island, Slump, Volcano-tectonic uplift,
Vocanic spreading.
INTRODUCTION
Ischia island is located over the Campania sector of Eastern
Tyrrhenian margin and represents the sub-aerial section of a
larger, E-W trending volcanic ridge including others submerged
or buried volcanic edifices. The island itself result from the
coalescence of a multitude of small to medium scale eruptions
leading to the emplacement of domes, lava flow and pyroclastic
deposits and ignimbrites (VEZZOLI et alii, 1988) ranging from
alkali basalts to trachytes. The oldest basement dates back to 150
ky and crops out along the perimeter of the island especially to
the south. Latest eruption occurred in 1302 A.D. and together
with strong hydrothermal activity, ground uplift and seismic
shaking indicates the presence of a still active magmatic reservoir
at depth. Most recent (Holocene) magmatic activity with local
volcanic eruptions has clustered in the eastern island’s sector the
while central sector is dominated by the Mt. Epomeo, consisting
of an ignimbritic tuff (Green tuff Auct.) uplifted of 600-700 m in
the past 33ka.
In the past decade the island’s offshore has been the object of
extensive hydrographic and marine geophysical surveys that have
shown the structural complexity of the undersea sections and
have overall shown the importance of gravity failures in island’s
evolution. In particular a 1.5-3 km3 debris avalanche due to a
subaerial and/or submarine flank collapse was emplaced along
the steep and unbuttressed island’s flank during pre-historical or
even historical times (CHIOCCI & DE ALTERIIS, 2006; DE
ALTERIIS et alii, 2010) whereas three other similar deposits of
comparable volumes were found over the continental shelf to the
west and to the north (VIOLANTE et alii 2004; DE ALTERIIS &
VIOLANTE, 2009).
Here we report a previously unrecognized deep-seated slump
structure and associated surficial mass wasting phenomena which
occur off Ischia south-western flank. Recently acquired
_________________________
(*) Istituto per L’Ambiente Marino Costiero – Consiglio Nazionale
delle Ricerche, Calata Porta di Massa, Porto di Napoli, Napoli, Italia.
(**) Dipartimento di Geologi e Geodesia, Università di Palermo, Italia
hydrological and geophysical data lead to identify the
morphological features and the internal organization of the failed
sediments which spread along the continental slope. The extent
of this deep-seated deformations and the deep structural levels
involved lead to investigate on the influence played by volcanic
processes on slope failure.
DATA AND METHODS
Our dataset was acquired during the geophysical cruise
PECOS 2010 carried out on R/V Urania (Consiglio Nazionale
delle Ricerche, CNR, Italy) between December 22 th 2010 and
January 2nd 2011 in the frame of a project leaded by Istituto per
l’Ambiente Marino Costiero, (IAMC-CNR), Naples-Italy with
the collaboration of Dipartimento di Scienze della Terra e del
Mare (Palermo University), Palermo-Italy regarding coastal and
offshore slope instability in the Bay of Napoli.
The Ischia southern slope was explored through a multibeam
survey and a single-channel seismic survey. Acquisition was
carried out between 400 and 1200 m. The bathymetric data were
collected using a hull mounted Reson 8160 multibeam sonar.
Resolution resulted in a 20x20 m implemented with 50x50
gridded size provided by a previously collected data. The seismic
survey consisted of 6 dip-lines NNE-SSW run along the slope
and 5 cross lines parallel to the slope totalling 170 km. Average
spacing between diplines was slightly less than 1 km while
spacing between crosslines was variable from 1.2 to 2.5 km.
NNE-SSW and WNW-ESE directions. The acoustic source used
was a 1Kjoule high-energy power supply system with a multitips (400) sparker array, fired at 2s time interval.
RESULTS
The collected data show that a wide submerged area of 350
km2, between 400 to 1200 m depths is undergoing slow-moving
deformation and associated secondary mass wasting phenomena.
Morphological features include trenches, counterscarps, bulging
and both extensional and contractional features while internal
deformations show typical landward dipping reflectors with
strong evidence of synsedimentary faulting and asymmetric
anticlines.
Deformation processes operate at various scales generating
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86° CONGRESSO SOCIETÀ GEOLOGICA ITALIANA
18-20 SETTEMBRE 2012, ARCAVACATA DI RENDE (CS)
Fig. 1 – Geologic sketch map of the study area
folds with wavelength ranging from hundreds meters to
kilometers. Extensional and rotational rupture surfaces sole out at
various low-angle detachment planes located at depths from few
hundred meters to 1 kilometer in subsurface.
The internal organization of the failing mass shows different
pattern of deformation that allows the identification of three main
units: 1) a basal unit consisting of a very broad, asymmetric
slump fold with a wavelength of about 5 km and amplitude of
some 100 m. The fold axis is not vertical and the three
dimensional interpretation indicates that the structure is not
cylindrical. The fold strictly correlates with a morphological
bulge seen on bathymetry at about 20 km south of Ischia Island.
2) A wedge shaped intermediate unit characterized by
discontinuous and folded reflectors, locally showing basal
detachment planes and compressional features. 3) A surficial
slump unit affecting the upper and middle slope characterized by
a basal decollément surface and normal growth faults that sole
out at depths ranging from 70 to 40 m in subsurface. It is still
unclear whether the landslide process can be favored by the
volcano-tectonic evolution and rapid vertical accretion of Ischia
volcano or is solely due to possibly volcanic spreading of the
Ischia Island.
REFERENCES
CHIOCCI, F. L. & DE ALTERIIS, G. (2006) - The Ischia debris
avalanche. First, clear submarine evidence in the
Mediterranean of a volcanic island pre-historic collapse.
Terra Nova, 18, 202–209.
DE ALTERIIS, G., INSINGA D. ET AL. (2010) - Age of submarine debris
avalanches and tephrostratigraphy offshore Ischia Island,
Tyrrhenian Sea, Italy. Marine Geology 278 (2010) 1–18.
DE
ALTERIIS, G. & VIOLANTE, C. (2009) - Catastrophic landslides
off Ischia volcanic island (Italy) during prehistory. In: C.
Violante, (ed.) Geohazard in Rocky Coastal Areas. Geological
Society, London, Special Publications, 322, 73–104.
VEZZOLI, L. (1988) Island of Ischia. Quaderni de ‘La Ricerca
Scientifica’ Progetto finalizzato ‘Geodinamica’, CNR
Monografie finali, 10.
VIOLANTE, C., BUDILLON, F., ET AL. (2004) - Submerged
hummocky topographies and relations with landslides on the
northwestern flank of Ischia island, southern Italy. In:
‘Occurrence and mechanisms of flow-like landslides in
natural slopes and earthfills’, Sorrento, 14–16 May 2003.
AGI, 2, 309–315.
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© Società Geologica Italiana, Roma 2012
A cliff overstep model for high-gradient shelves: the case of the
Ionian Calabrian Margin (southern Italy)
MASSIMO ZECCHIN (*), SILVIA CERAMICOLA (*), EMILIANO GORDINI (*), MICHELE DEPONTE (*),
SALVATORE CRITELLI (**)
Key words: Calabrian shelf, post-LGM transgression, subbottom
profiles.
The present study is focused on features developed during the
post-LGM transgression on the narrow, high-gradient shelf off
the Crotone area (southern Italy) and on the southern part of the
Amendolara palaeo-island (API). In particular, peculiar features
such as submerged coastal cliffs and a seabed typified by
irregular step-like geometry characterize the present area. We
recognized this area as suitable to develop a transgressive model
for very high-gradient settings characterized by coastal cliff
development and irregular topography. Such a model may be
useful in recognizing and understanding the features and style of
transgression and variations in its rate, particularly for the postLGM glacio-eustatic rise.
The seabed morphology of the Ionian Calabrian margin
reflects the complex interplay between the south-eastward
migration of the Calabrian accretionary wedge since midMiocene and the rapid uplift of onshore and shallow shelf areas
since mid-Pleistocene (MALINVERNO & RYAN, 1986; BONARDI et
alii, 2001). The uplift, documented by a staircase of marine
terraces in the subaerial Crotone Basin, still continues today, and
it has been characterized by a rate that, in this area, approximated
1 m/ka (ZECCHIN et alii, 2004; ANTONIOLI et alii, 2006).
The geophysical data used for this study consist of CHIRP
subbottom profiles (SBP) acquired across the Ionian shelf margin
(ISM) and the southern side of the API. The information coming
from the acoustic character of the SBPs have been combined with
the morpho-bathymetric information coming from a highresolution multibeam dataset.
Two seismic units (Unit 1 and Unit 2), separated by a key
stratal surface (Unconformity U) are recognizable in the
considered SBPs, both along the ISM and API.
Unit 1 is the lower unit, and is truncated above by U. This
_________________________
(*) OGS (Istituto Nazionale di Oceanografia e di Geofisica Sperimentale),
Borgo
Grotta
Gigante
42/c,
34010
Sgonico
(TS),
Italy
([email protected])
(**) Dipartimento di Scienze della Terra, Università della Calabria, 87036
Arcavacata di Rende (CS), Italy
unit is almost opaque along the ISM, but it may show basinwardinclined to variably folded reflectors along the API. A prograding
wedge, typified by basinward-inclined oblique reflectors that
downlap on a less inclines reflector, is recognizable between 90
and 130 m water depth at the margin of the API and locally along
the ISM.
The unconformity U separates the older Unit 1 from the
younger Unit 2, and is characterized by both concave- and
convex-up profiles in dip direction. It exhibits a variable dip from
0.5° to a maximum of ca. 30° at relict scarps locally exposed.
One of these features is recognizable between ca. 75 and 100 m
water depth along both the ISM and API.
Unit 2 is up to 30 m thick and locally appears as a prograding
wedge whose reflectors downlaps on the unconformity U. In
other cases, it shows onlap relationships with U.
The unconformity U, which truncates a unit characterized by
variably inclined reflectors (Unit 1), is overlain by a younger unit
(Unit 2), and is locally exposed forming scarps, represents a
surface of regional significance. In particular, it is interpreted as a
wave ravinement surface (WRS), produced by wave erosion on
the shelf during the post-LGM transgression, truncating a PlioPleistocene unit. The prograding wedge located between 90 and
130 m water depth in Unit 1 is interpreted as the lowstand wedge.
The deposition of Unit 2 above U has been related to the postLGM glacio-eustatic rise.
The scarp recognizable between 75 and 100 m water depth
along both the ISM and API is interpreted as a partially preserved
palaeo-coastal cliff. Moreover, such a depth closely matches with
the depth range of melt-water pulse (MWP) 1A, during which the
eustatic sea-level rose from 96 to 76 m below present sea-level,
between 14.3 and 14.0 ka BP (LIU & MILLIMAN, 2004). This
suggests a correlation between the stepped sea-level rise
following the LGM and the preservation of coastal cliffs along
the continental margins. In particular, it is suggested that the
palaeo-coastal cliff recognized between 75 and 100 m water
depth generated and started to recede during a phase of slow
eustatic rise, and was then overstepped and partially eroded
during a subsequent phase characterized by very rapid eustatic
rise (i.e. the MWP 1A), otherwise its progressive dismantling
would have occurred. This consideration is valid assuming a
rough balance between regional uplift and subsidence of glaciohydro-isostatic origin as shown by PIRAZZOLI et alii (1997).
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86° CONGRESSO SOCIETÀ GEOLOGICA ITALIANA
18-20 SETTEMBRE 2012, ARCAVACATA DI RENDE (CS)
Younger accelerations and decelerations of sea-level rise, such as
MWP-1B (58-45 m below present sea level, 11.5-11.2 ka BP),
could be responsible for the formation of some shallower scarps
found in our SBPs.
A transgressive model for high-gradient shelves during the
post-LGM glacio-eustatic rise is proposed. Where the
transgressed topography is very steep, coastal cliffs developed
and retreated during the initial phase of relatively slow sea-level
rise, due to wave erosion acting at the toe of the cliff. During
phases of very high rate of sea-level rise, coinciding with meltwater pulses, cliffs tended to be overstepped and not completely
eroded by the WRS. This model needs further testing in other
contexts characterized by high-gradient shelf topography, but it
has the potential to be useful in recognizing variations in the rate
of sea-level rise and in general in reconstructing the Late
Quaternary evolution of shelf to coastal areas.
REFERENCES
ANTONIOLI F., FERRANTI L., LAMBECK K., KERSHAW S.,
VERRUBBI V. & DAI PRA G. (2006) - Late Pleistocene to
Holocene record of changing uplift rates in southern
Calabria and northeastern Sicily (southern Italy, Central
Mediterranean Sea). Tectonophysics, 422, 23-40.
BONARDI G., CAVAZZA W., PERRONE V. & ROSSI S. (2001) Calabria-Peloritani terrane and northern Ionian Sea. In:
G.B. Vai and I.P. Martini (Eds.) - Anatomy of an Orogen:
The Apennines and Adjacent Mediterranean Basins. Kluwer
Academic Publishers, Bodmin, 287-306.
LIU J.P. & MILLIMAN J.D. (2004) - Reconsidering melt-water
pulses 1A and 1B: global impacts of rapid sea-level rise. J.
Ocean Univ. China, 3, 183-190.
MALINVERNO A. & RYAN W.B.F. (1986) - Extension in the
Tyrrhenian Sea and shortening in the Apennines as a result of
arc migration driver by sinking of the lithosphere. Tectonics,
5, 227-245.
PIRAZZOLI P.A., MASTRONUZZI G., SALIÈGE J.F. & SANSÒ P.
(1997) - Late Holocene emergence in Calabria, Italy. Mar.
Geol., 141, 61-70.
ZECCHIN M., NALIN R. & RODA C. (2004) - Raised Pleistocene
marine terraces of the Crotone peninsula (Calabria, southern
Italy): Facies analysis and organization of their deposits.
Sed. Geol., 172, 165-185.
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