The Clay minerals composition of the Bara Formation exposed at Ranikot and Lakhra and drilled
in the subsurface of Thar coalfield of Sindh Province, Pakistan.
By
A.A.A.Daahar Hakro1, M.A.A.Baig2, S.R.H. Baqri3 Qamaruddin Khokhar4, Mushtaq A.Pathan1
Abstract
The present studies were conducted for the identification of the clay minerals composition of
the Bara Formation exposed at Ranikot and lakhra areas in Lakhi Range and subsurface core
samples from SB-14 and ST-24 bore holes drilled in the coalfield of Thar. Seventy five samples
were acquired from the Bara Formation exposed at Ranikot and Lakhra anticlines. Twenty core
samples were collected from the core library of the GSP Quetta. Thirty four samples were
selected to identify clay minerals using scanning electron microscope and X-ray diffraction (XRD)
techniques. The mineral kaolinite was observed as spheroidal, stacks, thin idiomorphic plates
and as fragments. In addition, chlorite (Mg-rich, Fe-rich), illite and smectites were also identified
under SEM studies. The XRD investigations showed the presence of kaolinite, chlorite, random
mixed layer clay mineral, illite-montmorillonite, potassium feldspars, quartz, calcite and gypsum.
These minerals indicated that the Bara Formation was deposited under the fluvio-deltaic
depositional conditions and their detritus source rocks were the eroding igneous and
metamorphic rocks.
Keywords: Clay Mineralogy, Bara Formation, Ranikot, Lakhra, Thar Coalfield, SEM, XRD.
1.
Assistant Professor, Centre for Pure & Applied Geology, University of Sindh, Jamshoro.
2.
Professor (Rtd), Centre for Pure & Applied Geology, University of Sindh, Jamshoro.
3.
Stratigraphic, minerals, oil/gas, coal Consultant Geologist, United Kingdom.
4.
Lecturer, Centre for Pure & Applied Geology, University of Sindh, Jamshoro.
1
1. Introduction
Bara Formation enjoys a significant place in the Stratigraphy of Sindh / Southern Indus Basin
because a huge deposit of coal is being mined from it; its beautiful outcrops are exposed in the
Lakhi range which separates it from other stratigraphic units of the area. Clay minerals have
been considered as the good indicators for understanding the environments of deposition of
sediments; they also help in tracing their origin. They are hydrous aluminum (Mg, Fe) layered
silicates and are the essential part of Phyllosilicate group of minerals. Clay minerals are
originated in sediments and sedimentary rocks, as a result of their weathering and therefore
also called as secondary minerals which essentially are (< 2µ) or (0.002mm) in size. Chamely
(1989) and Weaver (1989) have documented voluminous books and research paper on Clay
Mineralogy. Clay minerals study provided important information regarding the depositional
environment and the origin of sediments of Bara Formation from Ranikot, Lakhra and Thar
coalfield areas. The major portion of the Bara Formation is made up of sandstone and shale.
Only few workers including Baig (1997), Abdallah et.al. (1997), Baig (2007), Baqri (1978), Baqri
(1980), Baqri (1983), Baqri (1984), Baqri (1997) and Baqri (2001) have contributed regarding the
clay mineralogy of the lithified rocks of southern Indus Basin, Pakistan. Abdallah et.al.(1997)
have published their research findings on the mineralogy of the Bulk-rock and clay fraction
samples of the of Bara Formation sediments from STP-11 and STP-13 boreholes of Thar
Coalfield. Baig (2007) recognized the species of kaolin and other clay minerals in the sediments
of Bara Formation from Thar Coalfield. Baqri (1984) described the distribution of minerals in the
coals of Lakhra (Coal bearing Bara Formation) of Sindh Province. Baqri (1997) discussed the
dispersion of sulphur in Paleocene coal (Bara Formation) of Sindh Province of Pakistan. The
study areas are located in the Map (01).
2. Materials and Methods
2
Seventy five samples were collected from the Lakhra and Ranikot anticlines and twenty core
samples are obtained from the core library of Geological Survey of Pakistan, Quetta. Thirty four
(34) samples were selected for clay mineralogical studies; twenty six samples were prepared
and analyzed by the Scanning electron microscope, whereas eight samples of the Lakhra
anticline were prepared and analyzed by the X-ray Diffraction.
Eight rock samples from Lakhra areas were selected for XRD analysis, following the procedures
of sample preparation of clay fraction described by Brindley and Brown (I980), Klug and
Alexander (1974), Cosgrove (1972), Baig (1982 & 2007) and Baqri (1980 & 1992). Samples were
left for overnight, in an oven at 110o C for removing moisture. Thirty gram of the each sample
was ground by hand in an agate mortar and pestle for 20 minutes. Oriented slides of clay
fraction (<2µ) were prepared for the study of clay mineralogy. Thirty gram powder of each
sample was added to distilled water in 250 ml beaker. The beaker was shaken in an ultrasonic
tank for 35 minutes for disintegration of clays particles. The beaker was left untouched for four
hours to allow the settling of coarse particles towards the bottom and the clay particles in
suspension. Upper four centimeters of the suspension were transferred in to a test tube of
centrifuge. After repeated centrifuging when the clear water appeared and the clay fraction
(<µ2) settled in the bottom of the test tubes. This clay fraction was spread and smeared onto a
glass slide with the help of spatula. Three slides of each sample were prepared, treated and
labeled as Normal slide (N) glycolated (G), heated (H), and acid digestion (A/D). All the samples
were scanned on the Siemens’s D-5000 X-ray Diffractometer at PCSIR, Laboratories Karachi. The
settings on the X.R.D were the following:
1.
Divergence slit and scatter slits ¼ degree,
2.
Receiving slit was 0.2 m.m,
3.
Scanning speed of goniometer was 1˚ degree, 2 θ/ minute,
4.
Recorder chart speed was 600 cms/hour 5-Time constant was 4 seconds.
Twenty six samples of Bara Formation from Ranikot, Lakhra area and Thar coalfield boreholes,
were selected for the SEM investigation. A representative portion of each sample was gold
coated and observed under Scanning Electron Microscope at General Centralized Laboratory
3
University of Karachi, Karachi. The clay minerals in the current study were identified by the Atlas
of petrology complied by Welton (1984) which illustrates the morphological diagnostic
characters of all clay minerals.
3. Results and Discussion
All samples of Bara Formation from Ranikot, Lakhra and SB-14 & ST-24 boreholes of Thar
Coalfield showed the occurrence of kaolinite (spheroidal), kaolinite (stack), kaolinite (thin
idiomorphic plates), and fragments of kaolinite, chlorite (Mg-rich), chlorite (Fe- and Al rich), illite
and smectite. Results of the SEM studies are tabulated in Table (1), and the SEM images of
identified clay minerals are displayed in Figs (1 to 3).
The method of X-ray diffraction was applied for the random powder data analyses and oriented
slides of clay fractions, to identify the clay minerals. Eight samples from the Lakhra area were
prepared and scanned on XRD, their results are shown in Table (2); and their diffractograms are
illustrated in Figs (03 to 07). The studied samples showed the occurrence of kaolinite, quartz,
chlorite, illite-montmorillonite, illite-montmorrillonite (1:2), Random mixed layer clay mineral
(regular interstratified illite/smectite 55% illite 45% smectite), mica-montmorrillonite (1:2) and
K-feldspar. The abundances of clay minerals are calculated and shown in Table (3).
Eight samples of the Lakhra area, showed kaolinite varies from 18.8% to 86.35%. Kaolinite
showed their presence in all the studied samples with XRD peaks at 12.40°, 2θ (7.14Å), 20.36, 2θ
(4.36 Å) &24.88, 2θ (3.56 Å). The Scanning Electron Microscopic (SEM) study also confirmed the
presence of kaolinite in all the studied samples. Perrin (1971) mentioned that the presence of
kaolinite indicated the rate of sedimentation and flocculation. Millot (1970) described that
kaolinite helps in understanding the Palaeogeography of an area it also enables in tracing the
proximity of shore-lines. Kaolinite can be concentrated under the fluvial or near-beach
depositional environment (Grim, 1968). The sandstone samples of Bara Formation showed
enrichment of kaolinite as compared to shales; sandstones and shales below the coal beds
contain more kaolinite than the shales which occurs above the coal beds, as observed by Glass
(1958). Kaolinite is present in fluviatile depositional environment with dominant concentration
(Weaver, 1956). Kaolinite is dominant clay mineral in the roof shales of the Lakhra and
Jhampeer coalfields (Baqri, 1978). Baqri (1983) noticed that kaolinite in seat earths and roof
4
shales were less crystalline than the kaolinite associated with coal. Kaolinite, pyrite and siderite
showed their presence in the coals of Lakhra (Bara Formation) reported by Baqri (1984). Baig
(1984) also found detrital kaolinite, chlorite and illite in the Oxford Clay and Kellaways
Formations from southern England. Abdallah et.al, (1997) reported the presence of kaolinite
and chlorite in the sediments of Bara Formation from STP-11 borehole of Thar Coalfield and
suggested the provenance of the studied sediments was the igneous and metamorphic rocks.
The rich percentage of kaolinite present in the Bara Formation from Ranikot, Lakhra and Thar
coalfield areas indicated a tropical and humid climate for the region and their association with
quartz, suggested that these fragments were supplied from the granites. The presence of high
concentration kaolinite in the investigated sediments strongly suggested fluvial or near-shore
type of depositional environments.
The Chlorite varies in Bara sediments of Lakhra area from 6.75% to 48.25%. Chlorites was
recognized by its XRD peaks at 30.00, 2Ө (2.97Ǻ) and (6.17o, 2Ө) (14.31 Å). Presence of chlorite
was indicated in all studied samples by Scanning Electron Microscopic (SEM) study. Chlorite is
detrital in nature and most likely was transported form metamorphic rocks. The term chlorite
was used for foliated clay minerals green in color with higher concentration of ferrous iron
(Werner, 1798). The origin of chlorite and other clay minerals has been described by Barshad
(1948) and Brindley (1951). Weaver (1989) mentioned that the chlorites are essential parts of
igneous and metamorphic rocks. Grim (1968) and Bradley (1945) investigated the
transformation of kaolinite in the recent sediments of Gulf of California and the sediments of
Pacific Ocean; they concluded that kaolinite gradually disappears in the marine sediments and
probably it altered to illite and chlorite. The chlorite usually is derived from the minerals which
contain rich amounts of iron, magnesium and calcium; these minerals occur in the basic igneous
or metamorphic rocks (Millot, 1970; Weaver and Pollard, 1973). Abdallah et.al, (1997) reported
the presence of chlorite and kaolinite in the sediments of Bara Formation from STP-11 borehole
of Thar Coalfield and suggested their provenance in the igneous and metamorphic rocks. Laghari
(2004) reported that the Igneous and metamorphic rocks are exposed in the Nagar Parker area
of Sindh.
Eight samples of the Bara Formation of Lakhra area indicated the range of Smectite from 2.46%
to 22.5%. Five samples of the studied sediment of Bara Formation from Lakhra indicated the
5
presence of smectite. It was identified by its diagnostic XRD peak at 15.82°, 2θ (5.58Å).Smectite
also showed their presence in the SEM investigation of the sediments of Bara Formation. Four
samples of studied sediments showed the presence of smectite (Montmorillonite). This clay
mineral is mostly formed with volcano-clastic sandstone which is leached by groundwater. The
increasing solubility of volcanic material permits the groundwater to quickly transfer to stability
field of montmorillonite (Weaver, 1989). According to Grim (1968) the term ‘smectite’ is used
for the group name of montmorillonite and other aluminous members. He agreed with the
original suggestions of Hofmann et. al.(1933). Maegdefrau and Hofmann (1937), Marshall (1935)
and Hendricks (1942), suggested the structural revision of smectite. This concept of structure
suggested that smectite comprises two silica tetrahedral sheets with a middle alumina
octahedral; these layers are stacked in a random manner. Smectite is recognized by their layers
which contracted and expanded on heating under glycol treatment. Smectite of Lakhra
sediments have showed positive correlation with random mixed layer clay mineral (illite –
montmorillonite) indicating that the origin of smectite is authigenic in the studied sediments.
Grim et.al (1937) proposed the term of illite for clay mineral, after the Illinois State of U.S.A It is
a mica-type clay mineral which exhibits significantly no swelling-lattices character (Grim, 1968).
Weaver (1989) described that illite is micaceous mineral, which contains smectite layers (0 to
20%). Illite showed its presence in all the studied samples of Bara Formation under SEM study.
The poor crystallinity of illite exhibited by some samples may be due to effects of weathering,
facies of sediments and being more sensitive to degradation and hydration under weathering
and transportation ( Dunoyer-De- Segonzac,1969).The high crystallinity showed by the illite
was shown in the coarser size particles. Siltstone contains better crystalline illite as compared to
shale. The medium –poor crystallinity illites are neoformed or transformed from other physils in
continental basins of a lacustrine or lagoonal type and are commonly associated with gypsum
and dolomite, and indicate the presence of evaporitic conditions (Kossovskaya and Drits, 1970)
and (Weaver, 1989).Illite is formed by the continental weathering of feldspar, micas, and
possibly volcano clastic materials; it may also be formed directly from the solution at both low
(neoformation) and high (hydrothermal) temperatures, and by the conversion of smectite to I/S
during burial (Weaver, 1989). The studied samples of Ranikot and Lakhra areas showed medium
to high crystallinity of illite, whereas; samples from Thar coalfield exhibited medium to poor
6
crystallinity of illite. The illite present in studied samples is detrital in nature and was
transported along with the weathered material from the pre-existing sedimentary rocks.
Mixed-layer clay mineral (Illite-montmorillonite), was identified by their XRD reflections at,
at12.50. 2°,2θ (7.07Å) and 26.58°,2θ.(3.35Å), and showed a range of 5.62%-36.02% in eight
samples of Bara Formation from Lakhra area. The high abundances of the mixed-layers in
layered rocks have been reported as the product of the weathering of the sediments, rich in
the content of illite and chlorite (Droste, et.al. 1960). Mixed layer clay minerals are originated
from degradation or aggradations of pre-existing clay mineral (Weaver, 1956). Clay minerals
change systematic diagenetically with depth in the subsurface samples (Burst, 1959, 1969).
Dunoyer- de- Segonzac (1970) explained that the regularly stratified mixed-layer clay minerals in
deep diagenesis are similar to allevardite or rectorite. They take up sodium during the
geochemical cycle before the development of sodic feldspars. Irregular mixed-layer clay
minerals are intermediate in the transformation process with suitable chemical composition.
Baqri (1978) mentioned that increase or decrease in the supply of Illite, chlorite and Kaolinite,
respectively, in the western clays from Sindh Province of Pakistan was due to sedimentation and
diagenesis.
The mixed layer clay mineral is a random mixture of the illite-montmorillonite. It varies from
14.90% to 33.57% in the Bara sediments of Lakhra area. The mixed clay mineral showed its
reflections as a long tail of the illite (001) reflection. It partly contracted on heating and partly
showed its expansion on glycolation. The mixed layer clay mineral was most likely originated
due to degradation of illite in comparatively fresh to brackish water environments.
5.
Conclusion
Considering the above discussion, this study may concluded as under:
1.
The clay mineral kaolinite (spheroidal, stack, thin idiomorphic plates and fragments of
kaolinite), chlorite (Mg-rich, Fe-Al rich), illite and smectite are identified from the sediments of
Bara Formation through SEM.
2.
Kaolinite, quartz, chlorite, illite-montmorillonite, illite-montmorrillonite (1:2), Random
mixed layer clay mineral (regular interstratified illite/smectite 55% illite 45% smectite), micamontmorrillonite (1:2) and K-feldspar clay minerals are recognized by XRD.
7
3.
4.
5.
6.
7.
The kaolinite mineral is present in both forms (Neoformed and Detrital) of origin. The
spheroidal forms of kaolinite shown in SEM images exhibited their detrital origin. The positive
correlation of kaolinite with smectite indicated the origin of kaolinite as neoformation.
The chlorite is detrital which showed the provenance.
The Mixed-layer minerals may be the alteration product of illite; this alteration might
have occurred during the transportation and sedimentation of the detritus.
The studied sediments (Bara Formation) were deposited under fluvio-delta conditions.
The provenance of the studied sediments most probably was in the acidic igneous/basic
igneous and metamorphic rocks belong to the Nagarparkar Igneous and Metamorphic
Complex, which is exposed in the southern side of the studied areas. These rocks are the
extension of Indian shield rocks.
5. Acknowledgement
The authors are grateful to the scientific officer, Mr. Kamalludin Shaikh, PCSIR laboratory
Karachi and Mr. Yousuf of General Centralized Laboratory (GCL), University of Karachi, for the
permission of using the XRD Lab facilities and his fruitful suggestions are also acknowledged.
Authors are also thankful to the Prof. Dr. Sarfraz H. Solangi, Director, Centre for Pure and
Applied Geology, University of Sindh, Jamshoro, for his moral support and arranged the SEM
atlas of clay minerals. We are indebted to Mr. Mirza Talib Hassan, Former Director General,
Geological Survey of Pakistan, Quetta, for his support, encouragement, suggestions and
cooperation. Author is also appreciative to Dr. Raza Ali Shah, Director and In charge of Core
library of GSP, Quetta, for his permission and arranged the samples.
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11
Table (1): The clay minerals of Bara Formation from Ranikot, Lakhra and SB-14 & ST-24
Boreholes of Thar Coalfield.
Ranikot
Sample
Mineral which has been found in SEM
S-6Ra(E)
Kaolinite (Spheroidal)
S-9Ra(E)
Chlorite (Mg rich), Kaolinite
S-14Ra(E)
Quartz & Kaolinite (Spheroidal)
S-18Ra(E)
Quartz, Kaolinite (Spheroidal) & Chlorite (Mg-rich/Illite)?
S-21Ra(E)
Kaolinite(stack), potash feldspar & Chlorite (Fe-rich)
S-22Ra(E)
Quartz, Kaolinite
S-23Ra(E)
Quartz, Kaolinite & Chlorite,
S-29Ra(E)
Quartz, Kaolinite (Spheroidal), & Smectite/ Montmorrillonite,
S-35Ra(E)
Chlorite (Fe-rich), Kaolinite (stack),Quartz, kaolinite (stack) and Chlorite (Fe-rich)
S-40Ra(E)
Quartz, Kaolinite, Kaolinite (thin idiomorphic plates), Quartz, Kaolinite (Spheroidal)
S-46Ra(E)
Quartz, Kaolinite, Quartz Kaolinite (Spheroidal).
Lakhra
Sample
Mineral Identified
S-8La(E)
Quartz
S-10La(E)
Montmorrillonite
S-12La(E)
Fragments of Kaolinite
S-13La(E)
Quartz, Fragments of Kaolinite (thin idiomorphic plates)
S-10La(W)
Kaolinite (Spheroidal), Montmorrillonite
Thar Coalfield
Sample
Mineral Identified
12
SB-1
Kaolinite , Chlorite (Fe rich,) & Chlorite (Mg rich)
SB-3
Chlorite (Fe- rich,)&Kaolinite
SB-5
Kaolinite & Chlorite (Fe &Al-rich)
SB-7
Kaolinite & Chlorite (Fe- rich),
SB-10
Kaolinite
ST-1
Chlorite (Fe rich), kaolinite (thin idiomorphic platelets) & Illite (platy).
ST-3
Chlorite (Fe rich), Kaolinite
ST-5
Chlorite, Montmorillonite, Kaolinite.
ST-7
Chlorite (Fe rich ), Chlorite (Fe-Al rich) (vermiform), Kaolinite
ST-10
Chlorite(Fe rich), Kaolinite.
Table (2): Calculated abundances of Clay minerals of samples from Lakhra
Sample
Mineral Name
D-value & 2Ɵ Intensity count % Formula
Figure
Total amount in
sample
1la(E)
Illite-Montmorillonite
5.58-15.82
3027
1
3027
16.34%
Smectite
5.11-17.33
740
1
740
3.99%
Kaolinite
24.99-3.56
6418
2
12836
69.31%
37.63-2.38
954
1
954
5.15%
Total
18298
94.79%
Kaolinite
11.91-7.42
579
2
1158
71.79%
Chlorite
30.19-2.95
450
1
450
27.9%
Total
1029
99.79%
Anatase
Factor = 100/18298 = 0.0054
4La (E)
Factor = 100/1608 = 0.062
13
8La (E)
Kaolinite
12.50 - 7.07
238
2
476
42.84%
Smectite
17.86 - 4.96
250
1
250
22.5%
24.67-3.60
373
1
373
33.57%
Total
1099
98.98%
Random mixed layer (Illitemontmorillonite)
Factor = 100/1099 = 0.090
13La(E)
Kaolinite
12.50 - 7.07
376
2
752
18.8%
Illite-Montmorillonite
26.46-3.36
1298
1
1298
32.45%
Chlorite
30.00 - 2.97
1930
1
1930
48.25%
Total
3980
99.5%
Factor = 100/3980 = 0.025
1La(W)
Kaolinite
12.50 - 7.07
7996
2
15992
86.35%
I-M
20.00-4.43
1041
1
1041
5.62%
Anatase
37.63-2.38
1311
1
1311
7.07%
Total
18344
99.04%
Factor = 100/ 18344 = 0.0054
4La(W)
Kaolinite
11.93-7.11
2060
2
4120
61.8%
Mixed Layer
27.51-3.24
529
1
529
7.93%
Chlorite
29.5-3.02
450
1
450
6.75%
Smectite
17.43-5.08
337
1
337
5.05%
Total
6639
95.57%
Factor = 100/6639 =0.015
8La(W)
Chlorite
6.01-14.67
3252
1
3252
21.13%
Kaolinite
12.50-7.07
5801
2
11602
75.41%
Smectite
17.43-5.08
379
1
379
2.46%
Total
15233
99%
Factor = 100/ 15233 = 0.0065
10La(W)
Kaolinite
12.50-7.07
315
2
630
34.65%
Smectite
18.00-4.92
265
1
265
14.57%
Random mixed layer (Illitemontmorillonite)
24.21-3.67
271
1
271
14.90%
26.57-3.35
655
1
655
36.02%
Total
1821
100%
Factor = 100/ 1821 = 0.055
14
Table (3): Correlation between Clay Minerals of Bara Formation from studied areas
Clay Minerals
Correlation
coefficient
Clay Minerals
Correlation
coefficient
Random mixed layer (I-M)VS Kaolinite
+1
Kaolinite VS Chlorite
-0.55
Random mixed layer (I-M)VS Chlorite
-1
Kaolinite VS Smectite
-0.75
Random mixed layer (I-M)VS smectite
+1
Kaolinite VS Random mixed layer (I-M)
+1
Random mixed layer (I-M)VS ML
NA
Kaolinite VSM-L
-0.80
Smectite VSML
NA
Chlorite VS Kaolinite
-0.55
Smectite VS Random mixed layer (I-M)
+1
Chlorite VS Smectite
-1
Smectite VS Chlorite
-1
Chlorite VS M-L
+1
Smectite VS Kaolinite
-0.75
Chlorite VS Random mixed layer (I-M)
-1
Map 01: Location Map showing studied areas of Sindh Province.
15
16
K
K
K
C
K
K
C
K
C
K
C
K
A
B
K
K
C
K
K
Q
K
K
K
K
D
E
F
C
F
K
F
C
K
K
K
Q
C
G
H
C
I
Q
Q
C
Q
K
K
J
C
Q
K
L
17
Q
K
K
K
C
S
K
C
S
M
Q
N
O
K
Q
K
Q
C
Q
K
K
K
P
Q
R
K
Q
Q
K
K
K
S
Q
Q
T
U
Figure (01): SEM images of Bara Formation samples from Ranikot.
Note: Labels on the figures stand for the minerals listed below:
Q=
Quartz, K=
Kaolinite, C=
A&B-
Kaolinite (Spheroidal)
C-
Chlorite Mg-Rich
D&E-
Kaolinite = Sample 9Ra (E)
Chlorite, S=
Smectite, I =
Illite
= Sample 6 Ra (E)
= Sample 9Ra (E)
= Sample 14 Ra (E)
18
F-
Quartz & Kaolinite (spheroidal)
G-
Quartz&Koalinite
H-
Chlorite Mg-rich/Illite?,
1.
= Sample 14 Ra (E)
= Sample 18 Ra (E)
= Sample 18 Ra (E)
Kaolinite (stack) & potash feldspar
= Sample 21 Ra (E)
J-
Chlorite Fe-rich,
= Sample 21 Ra (E)
K-
Quartz & Kaolinite,
= Sample 23 Ra (E)
L-
Quartz & Chlorite,
= Sample 23 Ra (E)
M-
Quartz & Kaolinite (spheroidal)
= Sample 29 Ra (E)
N-
Smectite/ Montmorrillonite,
= Sample 29 Ra (E)
O-
Chlorite Fe-rich & Kaolinite (stack)
P-
Quartz,& kaolinite (stack) and Chlorite Fe-rich.
= Sample 35 Ra (E)
Q-
Quartz & Kaolinite,
= Sample 40 Ra (E)
R-
Kaolinite (thin idiomorphic plates),
S-
Quartz & Kaolinite (spheroidal).
= Sample 40 Ra (E)
T-
Quartz & Kaolinite,
= Sample 46 Ra (E)
U-
Quartz Kaolinite (spheroidal).
= Sample 46 Ra (E)
S
S
= Sample 35 Ra (E)
= Sample 40 Ra (E)
Q
K
K
Q
K
S
A
K
K
Q
K
B
C
19
K
S
K
S
K
D
S
E
Figure (02): SEM images of the Bara Formation from Lakhra areas
1.
Montmorrillonite(Hectorite)
= Sample-10 La(E)
2.
Fragments of Kaolinite
= S-12 La(E)
3.
Quartz & Fragments of Kaolinite (thin idiomorphic plates)
= Sample 13La(E)
4.
Kaolinite (spheroidal)
= S10La(W)
5.
Montmorrillonite (Hectorite)
= S10La(W)
20
C
K
K
C
C
C
K
K
C
C
C
A
B
C
C
K
K
C
K
K
C
K
K
C
D
E
K
C
K
K
F
C
C
C
K
C
K
G
H
K
C
I
K
K
K
K
K
K
K
K
K
K
K
L
M
21
C
I
K
C
C
K
I
K
C
N
I
O
P
K
C
C
I
K
C
C
C
K
C
C
K
Q
R
C
C
S
K
K
K
S
S
S
K
C
T
K
U
C
S
S
V
C
S
S
C
S
S
C
W
C
K
S
C
C
C
C
C
C
C
X
Y
22
K
C
K
K
K
K
C
C
K
C
Z
K
C
A1
K
K
A2
Figure (03): SEM images of SB-14 & ST-24 borehoels of Thar Coalfield
23
Kaolinite
Kaolinite
I-M
Figure 04:Diffractograms of S-1 Bara Formation from Lakhra area.
24
Kaolinite
Chlorite
M-L
Chlorite
Kaolinite
Figure (05):Diffractogram of S-4 Bara Formation from Lakhra area.
25
26
Random mixed layer I-M
Smectite
Quartz
Chlorite
Kaolinite
Kaolinite
I-M
Figure (06):Diffractograms of S-8 Bara Formation from Lakhra area.
27
Figure (07):Diffractograms of S-10 Bara Formation from Lakhra area.
28