XRPD (Rietveld method),TG, DTG and
DTA investigation of
SAFOD cuttings (10366-10430)
Federico Zorzi1, Fabio Ferri1 and Giulio Di Toro1,2
1, Dipartimento di Geoscienze, Università di Padova, Italy
2, Istituto Nazionale di Geofisica e Vulcanologia, Roma, Italy.
pyrite
plagioclase
calcite
quartz
quartz
microcline
mixed smectite-illite
XRPD – SAFOD cuttings 10366-10430
The mineral composition of the cuttings was determined from XRPD data.
The low angle broad peaks evidence the presence of illlite + mixed layer
smectite-illite + chlorite which cannot be resolved.
RIETVELD ANALYSIS
observed
calculated
illite structure inadequate to fit the low angle data
The quantitaive determination of the phases was
performed with Rietveld analysis on XRPD data.
Since it was not possible to enrich and separate the
clayey fraction, in the refinement strategy all the clays
were treated as amorphous material and 10 % wt of
corundum was added as inner standard.
Quartz
57.2%
Plagioclase
14.1%
Calcite
2.8%
K-feldspar
6.5%
Pyrite
1%
Chlorite
4.4%
Clays
14%
THERMAL GRAVIMENTRY (TG), DIFFERENTIAL THERMAL GRAVIMETRY (DTG),
DIFFERENTIAL THERMAL ANALYSIS (DTA)
0
DTG
%wt loss
-1
1.5 %wt loss
due to illite-smectite
decomposition
-2
-3
-4
TG
-5
840
-6
830
820
Dt
810
DTA
800
790
780
770
760
0
100
200
300
400
500
600
700
Temperature (°C)
800
900 1000
The thermal
analysis suggest
that clay amount in
the cuttings is
around 10-15% wt
which is in
agreement with data
obtained from the
Rietveld refinement