CHAPTER-VII

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CHAPTER-VII

GEOCHEMICAL CHARACTERISTICS

7.0. Introduction of Sedimentary Geochemistry : Geochemistry of sedimentary rocks

can be used to infer source composition, weathering, transport history and depositional

conditions of sedimentation. There are number of advantages of geochemical studies in

provenance studies of sedimentary rocks over the mere petrographic observations, hence

combination of both the studies would be of help in deciphering the depositional

environment, metallogeny and tectonic interpretations (McLennan et al., 1993).

Geochemical characterization is: (i) applicable in case of both coarse grained and fine

grained sedimentary rocks, but provenance study of very coarse grained as well as fine

grained rocks are not possible by petrographic studies and (ii) geochemistry is applicable in

mineralogically altered samples also where alteration has not affected the bulk-rock

chemistry (McLennan et al.,1993). Many workers in sedimentary geology have also

recognized the importance of chemical composition of sedimentary rocks as they

indicate the nature of their source rocks which in turn, are also related to their tectonic

setting (Roser and Korsch, 1986 & 1988; Floyd et al., 1991 ; McLennan et al., 1993).

It is generally regarded that the geochemical composition of terrigenous sedimentary rocks

is a function of many factors, such as provenance, weathering, transportation and

diagenesis (Bhatia, 1983). Investigations on geochemical characteristics of ancient and

modern detritus have been carried out in order to infer the source rocks, provenance and

tectonic setting by various workers (Bhatia, 1983; Bhatia and Crook, 1986; Roser and

Korsch, 1986, 1988; McLennan et al., 1993; Nesbitt and Young, 1996 and many others).

Roser and Korsch (1986) also used the major oxides to infer tectonic settings. Various

workers have utilized trace elements and REE in the provenance study of sediments (Bhatia

and Crook, 1986; Feng and Kerrich, 1990; Holland, 1978).

In addition, certain trace element ratios including REE were also used by different workers

to decipher provenance study and tectonic setting of the sedimentary rocks (Taylor and

McLennan, 1985; Cullers et al., 1988; Cullers, 1994, 2000; Cullers and Podkovyrov, 2000;

McLennan 1989; Nesbitt 1979; Girty et al. 1994; McLennan and Taylor, 1991).

Wronkiewicz and Condie (1987) have utilized geochemical tools to infer source-area

166

weathering and their provenance for Archean shales from Witwatersrand Supergroup,

South Africa. Arora and Naqvi (1993) utilized geochemistry in understanding the exogenic

processes under different climatic and physio-chemical conditions of the Archean

sediments whereas Bhusan and Sahoo (2010) have attempted geochemistry in

understanding the Archean-Proterozoic boundary in Dharwar Craton of South India.

Fareeduddin. and Basavalingu (1988) have also given a good account of Sedimentology,

mineralogy and geochemistry of Kalasapura conglomerates of Dharwar Craton.Kalsbeek

and Frei (2010) have attempted geochemical data of Precambrian sedimentary rocks to

solve stratigraphical problems in Volta Basin of Ghana. Armstrong-Altrin et al. (2004),

Rashid (2005), Nagarajan et al. (2007), Hegde and Chavadi (2009) and Bakkiaraj et al.

(2010) have used various geochemical parameters to infer the source rock character and

tectonic setting of clastic sedimentary rocks. Osae et al. (2006) and Deru et al. (2007) have

used petrography and geochemistry to infer provenance and tectonic setting of

Paleoproterozoic Buem sandstones of southeastern Ghana and clastic sedimentary rocks

from SE margin of the Yangtze Block of South China respectively.

Jafarzadeh and Hosseini-Barzi (2008) have used geochemical characters to decipher the

provenance and tectonic setting of Ahwaz sandstone of Zagros, Iran. Raza et al. (2010)

have also attempted geochemistry to infer provenance and weathering history of Archaean

Naharmagra quartzite of Aravalli craton, NW Indian shield. Recently, Sahraeyan and

Bahrami (2012) have used geochemical data to explain the paleoweathering condition,

provenance characterization and tectonic setup of sandstones from Aghajari Formation in

folded Zagros, Southwestern Iran.

Thus understanding geochemical characters of both host rocks and ore minerals help in

understanding and characterizing the source of sediments i.e. provenance, source rock

weathering and tectonic setting of sedimentary rocks especially the QPC hosted uranium

mineralization. However, such detailed geochemical studies are very limited in

Singhbhum-Orissa Craton of eastern India especially in siliciclastic sequences deposited

along the margin of Singhbhum granite batholiths. Therefore, in this study geochemical

approaches have been addressed to infer chemical classification, paleo-weathering

condition, provenance characterization and possible tectonic setting of QPC-quartzite

sequence developed along Archean Bonai granite in parts of Sundergarh district of Orissa

of eastern India Craton.

167

For the purpose of geochemical studies, twenty one samples of QPC matrix (QPCm) and

fifteen samples of fine grained quartzites were subjected for whole-rock analysis and trace

elements using WDXRF at XRF Labs of AMD, DAE, Hyderabad. Na2O wt % in QPCm

was determined by flame photometry. Important rare elements such as Th, U, Sc and Hf

have been determined using ICP-MS at Chemical Laboratory of AMD, DAE, Hyderabad.

Loss On Ignition (LOI) of all samples were determined at Chemical Lab of AMD, DAE,

Jamshedpur. Similarly, REE determinations on 21 samples of QPCm and samples of 15

quartzites have been estimated using ICP-MS at Chemical Lab, AMD, Hyderabad. Au and

Ag contents were analyzed using Graphite-Furnace-AAS at AMD, DAE Chemical Lab,

Hyderabad. Five samples each of QPCm and quartzites containing gold were selected and

analyzed for their PGE. The various methods adopted for major, minor, trace and REE are

described briefly as follows:

Major and Trace Element Analysis using XRF : Fresh rock samples of QPCm and IOG

quartzites were reduced to small chips using laboratory- type jaw crusher and were

powdered to −200 mesh using Disc mills for maintaining the homogeneity and true

representativeness of the sample. Smaller representative volumes of the powders are

obtained by coning and quartering from which sample of 1g is transferred to cylindrical

sample dies and is palletized with boric acid as a backing, at a pressure of 25000 kg/cm2 in

a hydraulic press, to obtain pellets of 41 mm diameter.

The major, minor and some important selective trace elements of the samples were

analyzed at XRF Laboratory of Atomic Minerals Directorate for Exploration and Research

(AMD), Hyderabad using a PAnalytical Magi X Pro PW 2440 WDXRFS unit eqipped with

a 4 Kw , 60 Kv, 125 mA super sharp end window type X-Ray tube. International standard

reference materials (SRM’s) like, G-2, GA, GH, GS-N, JG2, MAN.SG3, ACE JG-1a (all

granites), JG-3, GSP-1 (granodiorite) etc. were used as calibration standards. The major

and minor elements were analyzed at 30 KV and 100mA using 300 m collimator, PX 1 and

LIF 200 dispersing crystals and gas flow proportional counter detectors with detection limit

of 0.01% where as the trace elements were analyzed at 50 KV and 60mA using 150 µm

collimator, LIF 220 Crystals and scintillation and/duplex detectors with detection limit of

10 ppm. The analytical precision (%RSD) and accuracy (%error) was within ±5% for

major elements , trace elements (> 30 ppm) and ± 10 % for trace elements (<30 ppm).

168

Determination of REEs, U and Th: Inductively Coupled Plasma Mass

Spectrometry (ICPMS): Model of ICP-MS : Platform XS; Standard Used: SY-2,

SY-4, MRG-1 (CCRMP – Canadian Certified Reference Material Project) was used.

Procedure adopted for determination of REE, U and Th: 0.1 gm sample was

accurately weighed in a clean platinum dish. It was moistened with 2 drops of water.

3ml of sub-boiled HF and 1ml of sub-boiled HNO3 was added and evaporated on

water bath, this process is repeated thrice. Further it was evaporated with only 3ml

sub-boiled HNO3 thrice. Finally 2ml of sub-boiled HNO3 and 15ml of Millipore

water is added to the dish and digested for 10 minutes. The solution is cooled and

transferred and made up to the mark in 100ml flask with Millipore water. REE, U,

and Th were determined in this solution using ICPMS.

7.1. Geochemistry of QPC matrix (QPCm) and IOG quartzites

7.1.1. Major Element Geochemistry Samples of QPCm and IOG quartzites were analyzed for their major, minor, trace and

REE. The results obtained are given in Tables 7.1 to 7.8. Major oxides of QPC and

IOG quartzites are given in Tables 7.1 and 7.2 respectively. In QPCm, SiO2 ranges

from 84.94-96.73(mean = 90.80), TiO2 from 0.10-1.22(mean= 0.46), Al2O3 from

1.45-7.56 (mean=3.56), Fe2O3(t) 1.03-5.25(mean=2.33), MgO from 0.06-1.41(mean

= 0.41), Na2O from 0.05-0.29 (mean=0.14), K2O from 0.19-2.03(0.83) whereas P2O5

varies from 0.02-0.10 (mean = 0.04) and MnO from <0.01 to 0.04(mean = 0.02). In

case of IOG quartzites these oxides ranges from 83.95-97.59(89.08), 0.01-0.57(0.19),

1.13-6.53(4.48), 0.11-0.55(0.28), 0.13-0.65(0.33), 0.08-0.34(0.21), 0.04-1.32(0.92),

0.02-0.07(0.04) and <0.01-0.02 (0.01) respectively (Table7.2). It may be noted that

silica content in QPCm is more than quartzites indicating more mature nature of

QPCm than quartzite which is indicated mineralogically by the presence of more

quartz and chert in QPC matrix. Maturity is also revealed by lower content of

alumina in QPCm (1.45 to 7.56 %, mean = 3.56) than in quartzites (1.13 to 6.53%,

mean = 4.48). Overall, it can be seen that the concentration level of all major oxides

except SiO2 are lower than their average concentration in UCC and PAAS (Tables

7.1 and 7.2).

169

High titanium in QPCm (0.10-1.22% TiO2) can be explained due to presence of

minerals like rutile, ilmenite and anatase in QPC matrix while low titanium in

quartzites (0.01-0.57% TiO2) are indicative of low abundance of Ti bearing minerals

like biotite, ilmenite, sphene, titanite and magnetite (Armstrong-Altrin et al., 2004).

High Al2O3/ TiO2 in both QPC and quatzites also indicate the presence of Ti-

bearing mafic phases like biotite, chlorite and ilmenite derived from basic rocks

along with felsic rocks (Chakrabarti et al., 2009). High titanium also points to a

mixed granite and greenstone provenance. Similarly, low Na2O and CaO contents in

both QPCm and quartzites are due to absence of both calcic and sodic plagioclase

which has been altered in the source rock due to chemical weathering or could have

destroyed during its transportation from source to depositional site which is also

corroborated by petrographic study and high plagioclase index of alteration (PIA).

Major Oxides Ratio in QPCm and Quartzites:

Major oxides ratios are useful in interpreting the maturity of sediments and their

provenance (Amajor,1987; La Maitre, 1976; Willis et al.,1988; Akarish and Gohary,

2011) SiO2/Al2O3 ratio is has been used as the index of sedimentary maturation

(Akarish and Gohary, 2011). This ratio generally increases due to increase of quartz

at the expense of feldspar and lithic fragments (less resistant) during the transport of

sediment and their recycling. SiO2/Al2O3 ratio is about 3 in basic rocks (basalts and

gabbros) and around 5 in acidic rocks like granites and rhyolites (La Maitre, 1976;

Roser et al., 1996).

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Table 7.1: Major oxides data of QPC (in wt % ; XRF data, Na2O- Flame photometry, LOI-Gravimetry)

S.No./Oxides

SiO2 TiO2 Al2O3 Fe2O3(T) MnO CaO MgO Na2O K2O P2O5 LOI SUM

DP/8 86.35 1.22 4.83 1.79 0.01 0.04 0.47 0.07 1.33 0.08 0.82 97.01 DP/81 93.45 0.47 1.45 5.25 0.02 0.04 0.45 0.12 0.19 0.06 0.73 102.23 DP/86 86.89 0.38 2.1 2.75 0.01 0.02 0.52 0.1 0.35 0.05 0.67 93.84 DP/90 91.75 0.86 2.14 4.8 0.01 0.04 0.81 0.16 0.2 0.1 1.19 102.06 DP/23 85.32 0.33 7.56 1.11 0.01 0.01 0.2 0.29 2.03 0.03 0.93 97.82 DP/2 92.6 0.73 2.01 3.28 0.03 0.04 1.41 0.23 0.23 0.08 0.86 101.5 DP/14 84.94 0.73 7.2 1.57 0.04 0.01 0.36 0.16 1.86 0.05 1.05 97.97

DP/28A 92.39 0.1 2.16 1.69 <0.01 0.01 0.39 0.08 0.52 0.02 0.45 97.81 DP/35 87.88 0.54 5.39 1.55 <0.01 <0.01 0.65 0.14 1.15 0.03 0.72 98.05 DP/55 90.23 0.12 3.74 2.21 0.01 0.05 1.26 0.21 0.63 0.06 0.98 99.5 Bali/1 86.33 0.17 4.92 3.65 <0.01 0.02 0.13 0.27 0.99 0.04 0.88 97.4 Bali/8 92.96 0.2 2.31 4.15 <0.01 0.03 0.26 0.17 0.49 0.04 0.44 101.05 Bali/10 93.13 0.35 1.74 3.24 <0.01 0.04 0.06 0.17 0.36 0.04 0.78 99.91 BBL/41 96.36 0.39 1.51 1.43 <0.01 0.01 0.25 0.11 0.47 0.02 0.16 100.71 BBL/52 88.42 0.87 4.19 1.76 0.01 <0.01 0.04 0.05 1.08 0.03 0.87 97.32 BBL/70 95.3 0.48 2.88 1.39 0.01 <0.01 0.23 0.09 0.85 0.03 0.56 101.82 BBL/74 92.17 0.48 3.9 1.12 0.01 <0.01 0.11 0.16 1.1 0.03 0.69 99.77 BBL/78 96.73 0.26 2.26 1.11 0.01 0.01 0.21 0.07 0.64 0.02 0.4 101.72 BBL/85 92.25 0.17 4.12 1.03 0.02 0.01 0.11 0.09 1.09 0.02 0.51 99.42 BBL/90 90.48 0.12 4.14 1.64 <0.01 0.01 0.09 0.13 1.13 0.02 1.93 99.69 BBL/100 90.90 0.64 4.12 2.31 0.01 0.03 0.57 0.08 0.82 0.05 0.45 99.98

Range 84.94-96.70 0.10-1.22 1.45-7.56 1.03-5.25 <0.01-0.04 <0.01-0.05 0.04-1.41 0.05-0.29 0.19-1.86 0.02-0.10 0.16-1.93 95.20-103.95 Average 90.80 0.46 3.56 2.33 0.02 0.02 0.41 0.14 0.83 0.04 0.77 --- UCC© 66.00 0.50 15.20 5.00 - 4.20 2.20 3.90 3.40 - - -

PAAS® 62.80 1.00 18.90 7.22 0.11 1.30 2.20 1.20 3.70 0.16 - -

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Table 7.2 : Major oxides data on IOG Quartzites (in wt %; XRF data, Na2O- Flame photometry, LOI-Chemical data

UCC© :Average of Upper Continental Crust (Values after Taylor and McLennan,1985 ). PAAS® : Average of Post Archean Australian Shale(Values after Taylor and McLennan).

S.No./Oxides SiO2 TiO2 Al2O3 Fe2O3(t) MgO MnO CaO Na2O K2O P2O5 LOI SUM

AK/DP/5 87.25 0.29 5.25 0.32 0.51 0.01 0.05 0.22 1.11 0.06 0.36 95.43

AK/DP/10 87.47 0.18 5.28 0.28 0.65 <0.01 0.03 0.18 1.24 0.04 1.19 96.55

AK/DP/11 85.92 0.29 5.47 0.27 0.45 0.01 0.04 0.13 1.28 0.06 0.17 94.09

AK/DP/16 83.95 0.57 6.53 0.55 0.46 0.02 0.04 0.08 1.77 0.07 1.19 95.23

AK/DP/20 85.83 0.19 5.65 0.37 0.43 0.01 0.02 0.08 1.40 0.04 0.32 94.34

AK/DP/45 84.05 0.20 6.52 0.21 0.15 <0.01 0.02 0.20 1.32 0.04 0.47 93.19

AK/DP/54 93.97 0.01 2.20 0.14 0.16 <0.01 0.03 0.16 0.18 0.04 0.19 97.09

AK/DP/64 87.54 0.13 5.16 0.43 0.52 0.01 0.04 0.32 0.93 0.02 0.59 95.69

AK/DP/73 87.21 0.27 5.25 0.33 0.41 0.01 0.03 0.30 1.07 0.03 0.41 95.32

AK/DP/76 87.41 0.04 5.12 0.23 0.13 0.01 0.03 0.20 0.95 0.05 0.68 94.85

AK/DP/89 92.86 0.04 3.03 0.22 0.28 0.01 0.05 0.33 0.44 0.05 0.33 97.64

AK/BBL/12 89.72 0.08 4.40 0.25 0.15 <0.01 0.02 0.17 0.93 0.03 0.56 96.32

AK/BBL/47 93.52 0.20 2.85 0.20 0.30 0.02 0.06 0.28 0.53 0.03 0.46 98.45

AK/BBL/59 97.59 0.15 1.13 0.11 0.24 0.01 0.04 0.34 0.04 0.03 0.32 100.00

AK/BBL/66 91.93 0.18 3.40 0.30 0.16 0.01 0.02 0.17 0.65 0.02 0.49 97.33

Range 83.95-97.59 0.01-0.57 1.13-6.53 0.11-0.55 0.13-0.65 <0.01-0.02 0.02-0.05 0.08-0.34 0.04-1.77 0.02-0.07 0.17-1.19 93.19-100.00

Average 89.08 0.19 4.48 0.28 0.33 0.01 0.03 0.21 0.92 0.04 0.52 96.10

UCC© 66.00 0.50 15.20 5.00 - 4.20 2.20 3.90 3.40 - - -

PAAS® 62.80 1.00 18.90 7.22 0.11 1.30 2.20 1.20 3.70 0.16 - -

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In the present study, SiO2/Al2O3 ratio is in the range of 11.29-64.45 (average = 25.54)

in QPC (Table 7.3) and 12.89-86.36 (average = 19.88) in IOG quartzites (Table 7.4)

which is significantly high. The average SiO2/Al2O3 ratios is 4 to 5 times more in

QPC and 3 to 4 times more for quartzites than the average values of mature

sediments, thus revealing mature nature for both QPC and quartzites, but QPC is

slightly more matured than quartzites. Depletion in Al2O3 and enrichment of SiO2

with respect to UCC and PAAS (Tables 7.1&7.2) is interpreted due to sedimentary

sorting and loss of fine sized clays and retention of sand sized grains (Borges et al.,

2008). High Al2O3 and K2O in quartzites compare to QPCm indicate slightly higher

content of clay in quartzites (Table 7.5).

Low values Al2O3/SiO2 in QPC (0.02-0.09) (Table 7.3) and IOG quartzites (0.012-

0.078) (Table 7.4) support quartz enrichment. The comparison of various oxides and

their ratios in QPCm and quartzites are shown in Table 7.5. Slightly higher potash

than sodium is due to presence of sericite, biotite and minor muscovite and clay in

matrix of both QPC and quartzite. High total Fe and MgO can be explained due to

presence of magnetite, ilmenite, pyrite goethite, minor hematite, limonite and chlorite

in QPC matrix.

K2O/Al2O3 ratio of terrigenous sedimentary rocks was used to decipher the original

composition of ancient sediments, because this ratio for clay minerals and feldspars

are different. The K2O/Al2O3 ratio for clay minerals range from 0.0 to 0.3 and for

feldspar, it ranges from 0.3 to 0.9 (Cox et al., 1995). In the present study, K2O/Al2O3

ratio for QPCm range from 0.09 to 0.31(mean = 0.23) and 0.04 to 0.27 (mean = 0.21)

for IOG quartzites. In both QPCm and quartzites, low values of K2O/Al2O3 ratio

indicate the presence of clay minerals and not feldspar. Petrographic study also

supports this observation. The comparison of all major oxides and ratios between

QPCm and quartzites are tabulated in Table 7.5.

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Table 7.3: Major oxides ratios of QPC (XRF data)

S. No/Oxides ratios Fe2O3(t)+ MgO Al2O3/SiO2 K2O/Na2O K2O/Al2O3 SiO2/Al2O3 Al2O3/TiO2 SiO2/MgO DP/8 2.26 0.06 19.00 0.28 17.88 3.96 183.72 DP/81 5.70 0.02 1.58 0.13 64.45 3.09 207.67 DP/86 3.27 0.02 3.50 0.17 41.38 5.53 167.10 DP/90 5.61 0.02 1.25 0.09 42.87 2.49 113.27

DP/23 1.31 0.09 7.00 0.27 11.29 22.91 426.60 DP/2 4.69 0.02 1.00 0.11 46.07 2.75 65.67 DP/14 1.93 0.08 11.63 0.26 11.80 9.86 235.94

DP/28A 2.08 0.02 6.50 0.24 42.77 21.60 236.90 DP/35A 2.20 0.06 8.21 0.21 16.30 9.98 135.20

DP/55 3.47 0.04 3.00 0.17 24.13 31.17 71.61 BALI/1 3.78 0.06 3.67 0.20 17.55 28.94 664.08 BALI/8 4.41 0.02 2.88 0.21 40.24 11.55 357.54

BALI/10 3.30 0.02 2.12 0.21 53.52 4.97 1552.17 BBL/41 1.68 0.02 4.27 0.31 63.81 3.87 385.44 BBL/52 1.80 0.05 21.60 0.26 21.10 4.82 2210.50 BBL/70 1.62 0.03 9.44 0.30 33.09 6.00 414.35 BBL/74 1.23 0.04 6.88 0.28 23.63 8.13 837.91 BBL/78 1.32 0.02 9.14 0.28 42.80 8.69 460.62 BBL/85 1.14 0.04 12.11 0.26 22.39 24.24 838.64 BBL/90 1.73 0.05 8.69 0.27 21.86 34.50 1005.33 BBL/100 2.88 0.05 10.25 0.20 22.06 6.44 159.47 RANGE 1.14-5.70 0.02-0.09 1.00-21.60 0.09-0.31 11.29-64.45 2.49-34.50 65.67-2210.50

AVERAGE 2.73 0.04 5.94 0.23 25.54 7.77 222.24

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Table 7.4: Major oxides ratios of IOG quartzites (in wt %, XRF data)

S.No /Oxides Fe2O3(T)+MgO Al2O3/SiO2 K2O/Na2O K2O/Al2O3 SiO2/Al2O3 Al2O3/TiO2 SiO2/MgO AK/DP/5 0.83 0.06 5.045 0.21 16.62 18.10 171.08 AK/DP/10 0.93 0.06 6.88 0.23 16.56 29.33 134.57 AK/DP/11 0.72 0.064 9.85 0.23 15.71 18.86 190.93 AK/DP/16 1.01 0.078 22.12 0.27 12.86 11.46 182.50 AK/DP/20 0.80 0.066 17.50 0.25 15.19 29.74 199.60 AK/DP/45 0.36 0.077 6.60 0.20 12.89 32.60 560.33 AK/DP/54 0.30 0.023 1.125 0.08 42.71 220.00 587.31 AK/DP/64 0.95 0.058 2.91 0.18 16.96 39.69 168.35 AK/DP/73 0.74 0.061 3.57 0.20 16.58 19.44 212.71 AK/DP/76 0.36 0.058 4.75 0.18 17.07 128.00 672.38 AK/DP/89 0.50 0.033 1.33 0.14 30.65 75.75 331.64

AK/BBL/12 0.40 0.049 5.47 0.21 20.39 55.00 598.13 AK/BBL/47 0.50 0.030 1.89 0.19 32.81 14.25 311.73 AK/BBL/59 0.35 0.012 0.12 0.04 86.36 753.00 406.62 AK/BBL/66 0.46 0.037 3.82 0.19 27.04 18.89 574.56

RANGE 0.30-1.01 0.012-0.078 0.12-22.12 0.04-0.27 12.89-86.36 11.46-753 134.57-672.38 AVERAGE 0.61 0.050 4.38 0.20 19.88 23.58 269.94

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Table 7.5: Comparison of various major oxides and their ratios in QPCm and quartzites.

Harker’ Plot : Harker plot for QPCm and quartzites have been shown in Fig.7.1 to

find out the relation of SiO2 with other major oxides in QPCm and quartzites. It is

evident from Fig.7.1 that most of the oxides show negative trend with increasing

SiO2 in both QPCm and quartzites. K2O, Al2O3, TiO2 show strong negative trend

whereas Fe2O3 show moderate to strong negative trend with increase in SiO2 content.

Moderate negative trend have been noted with CaO, MnO and MgO. This indicates

decrease in unstable components like feldspars and rock fragments and increase in

mineralogical maturity of the QPCm and quartzites in the study area (Gu et al.,

2002).

QPC m (n=21) Quartzites (n=15)

Oxides (Wt %) Range Mean Range Mean

SiO2 84.94-96.73 90.80 83.95-97.59 89.08

TiO2 0.10-1.22 0.46 0.01-0.57 0.19

Al2O3 1.45-7.56 3.56 1.13-6.53 4.48

Fe2O3(T) 1.03-5.25 2.33 0.11-0.55 0.28

MgO 0.06-1.41 0.41 0.13-0.65 0.33

MnO <0.01-0.04 0.02 <0.01-0.02 0.01

CaO <0.01-0.05 0.02 0.02-0.06 0.03

Na2O 0.05-0.29 0.14 0.08-0.34 0.21

K2O 0.19-2.03 0.83 0.04-1.32 0.92

P2O5 0.02-0.10 0.04 0.02-0.07 0.04

Al2O3/SiO2 0.02-0.09 0.04 0.012-0.078 0.05

K2O/Na2O 1.00-21.60 5.93 0.12-22.12 4.38

K2O/Al2O3 0.09-0.31 0.23 0.04-0.27 0.20

SiO2/Al2O3 11.29-64.45 25.54 12.89-86.36 19.88

Al2O3/TiO2 2.49-34.50 7.77 11.46-753 23.58

SiO2/MgO 65.67-2210.50 222.24 134.57-672.38 269.94

176

Fig.7.1. Harker plot for major oxides in QPC matrix and IOG quartzites, western margin of Bonai granite, Sundergarh district, Orissa.

177

7.1.2. Trace Element Geochemistry: The chemical signatures of trace elements are

mainly dependent upon the minerals where these elements reside. It has been shown

by many workers that most of the trace elements in clastic rocks reside in clay

minerals (Taylor and McLennan, 1985; Condie, 1991). The role of accessory

minerals in the trace element geochemistry has also been discussed and recognized

by many researchers (Yan et al., 2000; Singh and Rajamani, 2001). Trace element

data of QPC and IOG quartzites are given in Tables 7.6 and 7.7 respectively. Among

trace elements, U content in QPC ranges from 1.0 to 167 ppm (Average = 38.90ppm)

while their Th content shows variation from 5.0 to 143 ppm (Average = 46.33ppm)

which is higher than the U, Th content in both Upper Continental Crust (UCC) and

Post-Archean Australian Shale (PAAS) ( Table 7.3). In IOG quartzites, U and Th

content varies from 1.0 to 12 ppm (Average = 3.4 ppm) and Th from 1.0 to 26ppm

(Average = 8.33ppm). Thus both QPC and IOG quartzites in the study area are

enriched in U and Th content with respect to UCC and PAAS, though enrichment is

more in QPC than in quartzites. High U and Th content in QPC can be explained

either due to presence of uraninite or monazite grains and also due to presence of

secondary uranyl minerals and adsorbed uranium associated with goethite, limonite,

hematite and anatase.

Concentration of Rb, Ba and Sr are low in QPC and quartzites with respect to UCC

and PAAS reflecting paucity of K-feldspar and Ca-rich feldspar. Rb/Sr is also very

low, thus indicating alteration and weathering of feldspar either in the source area or

during transportation of sediments. Cr content in both QPC (94-580 ppm, average =

251.58 ppm) and IOG quartzites (51-315 ppm, average = 153 ppm) are higher than

UCC and PAAS (Tables 7.6 & 7.7). The high concentration of Cr is due to presence

of chromite and fuchsite mica in matrix of QPC and only fuchsite in quartzites.

Presence of chromite by SEM-EDS in QPC confirms this observation [(Fig. 6.3(30)].

The concentration of Cr in both QPC and quartzites together with high SiO2, U, Th,

La and Ce when compared to UCC indicates towards mixed source (Cingolani et al.,

2003). The presence of detrital chromite grains and higher concentration of Cr

indicate their derivation from mafic- ultramafic source rocks. Gorumahisani-

Badampahar and Tomka-Daitari IOG which is considered to have such older mafic-

ultramafic sequences could be source for Cr and minor Ni and Co in QPC (Haque et

al., 2001).

178

QPC shows low content of V, Rb, Ba, Sr, Zn, Zr, Hf with respect to UCC and PAAS

but higher concentration of U, Th, Pb, La, Ce, Y and Cr, Ni, Cu with respect to UCC

and PAAS (Table 7.3) whereas IOG quartzites are depleted in almost all trace

elements including U, Th, Pb, Y, La and Ce except Cr when compared to UCC and

PAAS (Table 7.4).

QPC generally show enrichment of Pb, Th, U, Cr, Co, Ni, La, Ce, Nd, Sm,Yb and Y

with respect to Upper Continental Crust(UCC) whereas quartzite show slight

enrichment only in Pb, U and Cr. In contrast to REE enrichment in QPC, quartzites

show depletion in REE with respect to both UCC and North American Shale

Composite (NASC). Both show depletion in Rb, Sr, Ba and Sc with respect to UCC

and NASC. QPC also indicate enrichment of Th, Cr, Co and REE but depletion in

Rb, Ba, Ti, Ni, Sc with respect to NASC (Figs. 7. 2a and 7.2b).

179

Table. 7.6: Trace element distribution in QPCm (all data in ppm, except Au in ppb; $ GF-AAS, *ICP-MS data and rest XRF data, Ni-AAS data)

UCC© : Average of Upper Continental Crust (Values after Taylor and McLennan,1985 ). PAAS® : Average of Post Archean Australian Shale(Values after Taylor and McLennan, 1985).

S. No V Cr Co Ni Cu Zn Rb Sr Ba Y* Zr Nb Ce* Pb Th* U* Hf* Sc* La*

DP/8 100 580 98 150 47 85 69 8.0 101 158 278 <5.0 293 117 63 41 5.0 4.0 198

DP/81 39 298 57 50 83 73 5.0 <5.0 5.0 94 98 <5.0 317 91 57 70 2.0 1.0 200

DP/86 31 239 50 26 52 79 15 8.0 103 51 77 <5.0 158 60 46 29 2.0 1.0 94

DP/90 69 535 100 16 101 81 <5 10 5.0 118 193 3.0 534 163 143 157 4.0 2.0 325

DP/23 28 173 41 32 8.0 15 85 6.0 175 45 135 <5.0 68 10 22 8.0 3.0 3.0 51

DP/2 59 436 82 33 89 206 1.0 <5.0 5.0 111 178 15 406 236 140 167 3.0 2.0 230

DP/14 59 349 96 56 21 18 84 7.0 132 97 205 <5.0 169 18 67 16 4.0 <1.0 110

DP/28A 9.0 134 50 72 61 <5.0 15 2.0 31 26 41 <5.0 69 60 101 131 2.0 <1.0 43

DP/35 45 315 49 26 28 18 57 2.0 20 68 179 4.0 133 15 39 11 4.0 3.0 83

DP/55 11 125 56 48 34 39 32 <5.0 14 37 58 <5.0 69 113 62 28 2.0 1.0 45

Bali/1 15 119 42 14 20 <5.0 40 <5.0 55 26 52 6.0 29 12 18 35 2.0 1.0 122

Bali/8 17 142 64 14 21 <5.0 28 10 42 9.0 47 6.0 39 54 9.0 15 2.0 <1.0 32

Bali/10 28 200 136 9.0 46 <5.0 20 <5.0 15 6.0 59 14 81 550 18 30 3.0 <1.0 51

BBL/41 33 180 46 20 11 <5.0 17 <5.0 14 58 102 5.0 103 27 10 5.0 2.0 <1.0 62

BBL/52 71 360 61 16 17 <5.0 35 <5.0 5.0 106 186 3.0 186 24 60 23 4.0 3.0 107

BBL/70 38 190 110 11 12 <5.0 28 <5.0 22 56 100 <5.0 123 78 24 12 2.0 2.0 76

BBL/74 <5.0 195 63 5.0 10 <5.0 35 2.0 52 62 126 <5.0 80 19 9.0 1.0 3.0 3.0 46

BBL/78 22 125 53 16 13 <5.0 22 4.0 53 51 62 32 47 32 5.0 3.0 2.0 2.0 31

BBL/85 15 121 102 5.0 13 <5.0 37 5.0 75 24 56 7.0 54 47 9.0 3.0 2.0 1.0 38

BBL/90 11 94 31 11 15 <5.0 33 7.0 81 21 23 <5.0 44 43 18 5.0 2.0 <1.0 27

BBL/100 52 369 59 50 43 26 27 3.0 24 89 182 7.0 142 18 53 27 3.0 2.0 82

Range <5.0- 100 94-580 31-136 5.0-150 8.0-101 <5.0-206 <5.0-85 <5.0-10 5-175 6.0-158 23-278 <.05-32 29-406 10-550 5.0-143 1.0-167 2.0-5.0 <1.0-4.0 27-325

Average 37.60 251.38 68.86 32.33 35.48 64.0 34.25 5.69 49.0 62.52 116.05 9.27 149.71 85.10 46.33 38.90 2.76 2.07 97.77

UCC© 60 80 10 20 25 71 112 350 550 22 190 25 64 20 10.7 2.8 5.8 - 30

PAAS® 150 23 55 50 85 160 200 650 27 210 19 80 20 14.6 3.1 5.0 - 38

180

Table. 7.7 : Trace element concentration in IOG quartzites ( in ppm), Cr, Rb, Ba, Zr, Pb-XRF, Ni, Cu-AAS, Y, Ce. Th, U, La, Sc, Hf- ICP-MS, Au-AAS Graphite furnace (n =15)

Co- <5ppm, Sr- <10ppm, -<10ppm; UCC© :Average of Upper Continental Crust (Values afterTaylor and McLennan,1985). PAAS® : Average of Post Archean Australian Shale(Values afterTaylor and McLennan).

Sample No. Cr Ni Cu Rb Ba Zr Pb Th U Sc Hf La Ce Y AK/DP/5 179 11 14 74 336 139 26 26 12 2.0 3.0 45 100 14 AK/DP/10 144 <5.0 6.0 11 343 115 79 13 5.0 2.0 4.0 27 50 11

AK/DP/11 210 8.0 7.0 38 275 195 52 17 6.0 2.0 7.0 29 57 15

AK/DP/16 315 18 12 97 319 212 20 25 7.0 4.0 5.0 52 109 28

AK/DP/20 143 10 13 69 195 89 12 7.0 3.0 2.0 3.0 20 40 14 AK/DP/45 175 <5.0 7.0 80 171 161 5.0 6.0 2.0 3.0 3.0 18 44 6.0

AK/DP/54 51 13 9.0 39 82 67 5.0 1.0 1.0 1.0 2.0 5.0 13 4.0

AK/DP/64 183 14 12 53 131 104 5.0 4.0 2.0 2.0 3.0 18 32 4.0

AK/DP/73 247 8.0 10 42 172 139 5.0 5.0 2.0 3.0 3.0 22 41 5.0 AK/DP/76 91 <5.0 10 45 113 74 5.0 2.0 1.0 3.0 2.0 12 20 3.0

AK/DP/89 94 <5.0 10 48 193 92 5.0 1.0 1.0 1.0 2.0 12 19 3.0

AK/BBL/12 97 <5.0 7.0 50 126 96 5.0 3.0 2.0 2.0 3.0 13 31 4.0

AK/BBL/47 125 5.0 9.0 37 115 97 5.0 5.0 2.0 2.0 3.0 15 27 6.0 AK/BBL/59 101 6.0 5.0 28 114 108 5.0 4.0 1.0 1.0 3.0 9.0 19 6.0

AK/BBL/66 140 8.0 10 31 120 68 5.0 7.0 4.0 2.0 2.0 25 45 6.0

Range 51-315 <5.0-18 5.0-14 11-97 82-343 67-212 5.0-79 1.0-26 1.0-12 1.0-3.0 2.0-7.0 5.0-52 13-109 3.0-28 Average 153.00 10.1 9.4 49.47 187.00 117.07 15.93 8.33 3.40 2.13 3.20 21.47 43.13 8.60

UCC© 80 20 25 112 550 190 20 10.7 2.8 - 5.8 30 64 22 PAAS® - 55 50 160 650 210 20 14.6 3.1 - 5.0 38 80 27

181

Enrichment of U, Th, Pb, La, Ce, Y in QPCm are due to presence of uraninite,

secondary uranyl minerals, adsorb uranium associated with goethite, limonite, thorian

uraninite, monazite grains, and REE bearing minerals like monazite, sphene, ilmenite

whereas Cr, Cu and Ni may be due to presence of chromite, fuchsite mica,

chalcopyrite and pyrite.

Fig.7.2a.Trace element distribution patterns in QPC and quartzites, western margin of Bonai granite, Orissa with respect to UCC .

Fig.7.2b.Trace element distribution patterns in QPC and quartzites, western margin of Bonai granite, Orissa with respect to NASC.

182

7.1.3. Important Elemental Ratios in QPCm and IOG quartzites:

Various critical elemental ratios of QPCm and IOG quartzites are given in Table.7.8

and 7.9 respectively. The comparisons of some critical elemental ratios between

QPCm and quartzites have been shown in Table 7.10. From Table.7.10, it can seen

that all elemental ratios viz. Th/Sc , La/Sc, Zr/Cr, Cr/Ni, Th/U, Cr/Th, Y/Ni, La/Th

are high in QPCm compared to quartzites, except Cr/Th. High ratio of these elements

are indicative of more contribution from felsic source for QPC detritus. However,

high Cr/Th ratios in quartzites compared to QPCm suggest slightly some contribution

from ultramafic provenance in quartzites.

The values of different elemental ratios including Eu/Eu* (Europium anomaly) and

Chondrite normalized La/Lu(CN) ratio are compared with different sources, it is seen

that all ratios like La/Sc and Th/Sc are comparable with the values noted in felsic

sources sediments. However, Cr/Th ratios in both QPC and quartzites are more than

felsic source and rocks from upper continental crust (UCC) and Proterozoic

sandstones but less than mafic sources, thus indicate minor contribution of mafic

source (Table 7.11). Eu/Eu* (Europium anomaly) in QPCm is lower than felsic and

sediments from other source rock but for quartzite, the values are within felsic

source. Chondrite normalized La/Lu (CN) ratio in QPC is higher than those noted in

UCC andProterozoic sediments and mafic source but nearer to those found in

sediments from felsic sources. Overall, both QPC and quartzites show their trace

elements character comparable with felsic source sediments.

183

Table 7.8: Important elemental ratios in QPC matrix

Ratios Th/U Th/Sc La/Sc Cr/Ni Co/Ni Cr/Th Zr/Sc Cr/Zr La/Co Zr/Cr Zr/Y La/Yb Rb/Sr Co/Th La/Th Y/Ni

DP/8 1.54 15.7 49.5 10.55 1.78 9.21 69.5 2.09 2.02 0.48 1.76 18.0 8.63 1.56 3.14 1.05

DP/81 0.81 57.0 200 4.45 0.85 5.23 98.0 3.04 3.51 0.33 1.04 40.0 - 1.00 3.51 1.88

DP/86 1.59 46.0 94.0 8.85 1.85 5.20 77.0 3.10 1.88 0.32 1.51 47.0 1.875 1.09 2.04 1.96

DP/90 0.91 7.15 162.5 13.05 2.44 3.74 96.5 2.77 3.25 0.36 1.64 54.2 - 0.70 2.72 7.38

DP/23 2.75 7.33 17.0 6.92 1.64 7.86 45.0 1.28 1.24 0.78 3.0 17.0 14.2 1.86 2.32 1.41

DP/2 0.84 70.0 115 2.03 0.38 3.11 89.0 2.45 2.81 0.41 1.60 32.8 - 0.59 1.64 3.36

DP/14 4.19 - - 12.5 3.43 5.21 - 1.70 1.15 4.18 2.11 22 12.0 1.43 1.64 1.73

DP/28A 0.77 - - 5.15 1.92 1.33 - 3.27 0.86 0.31 1.58 21.5 7.5 0.50 0.42 0.36

DP/35 3.55 13.0 27.7 9.84 1.53 8.08 59.67 1.76 1.69 0.57 2.63 20.75 28.5 1.26 2.13 2.62

DP/55 2.21 62.0 45.0 2.32 1.04 2.02 29.0 2.16 0.80 0.46 1.57 _ - 0.90 0.72 0.77

BALI/1 0.51 18.0 16.0 19.83 7.0 6.61 17.33 2.29 0.38 0.44 2.0 _ - 2.33 0.89 1.86

BALI/8 0.60 - - 23.67 10.67 15.78 - 3.02 0.50 0.33 5.22 _ 2.8 7.11 3.55 0.64

BALI/10 0.60 - - 100 68.0 11.11 - 3.39 0.375 0.295 9.83 85 - 7.56 2.83 0.67

BBL/41 2.0 - - 36.0 9.2 18.0 - 1.76 1.35 0.57 1.76 31 - 4.60 6.20 2.90

BBL/52 2.61 20.0 35.7 40.0 6.78 6.0 62.0 1.94 1.75 0.52 1.75 13.37 - 1.02 1.78 6.63

BBL/70 2.0 12.0 38.0 95.0 55.0 7.92 50.0 1.90 0.69 0.53 1.78 15.2 - 4.58 3.17 5.10

BBL/74 9.0 3.0 15.3 48.75 15.75 21.67 42.0 1.55 0.73 0.65 2.03 11.5 17.5 7.00 5.11 12.4

BBL/78 1.66 2.5 15.5 17.86 7.57 25.0 31.0 2.02 0.58 0.496 1.22 10.33 5.5 10.6 6.20 0.44

BBL/85 3.0 9.0 38.0 40.33 34.0 13.44 56.0 2.16 0.37 0.46 2.33 - 7.4 11.33 4.22 4.80

BBL/90 3.60 - - 13.43 4.43 5.22 - 4.09 0.87 0.24 1.10 13.5 4.71 1.72 1.55 1.91

BBL/100 1.96 26.6 41.0 6.47 1.04 6.96 91.0 2.03 1.39 0.24 2.04 136.7 9.0 1.11 1.55 1.78

Range 0.51-9.0 2.5-70 15.3-200 2.03-100 0.38-68 2.02-25 17.33-96.5 1.28-4.09 0.37-3.51 0.24-4.18 1.1-9.83 10.33-136.7 1.875-28.5 0.50-11.33 0.42-6.20 0.36-12.4

184

Table 7.9: Important elemental ratios in IOG Quartzite

S. No. Th/U Th/Sc La/Sc Cr/Th Zr/Sc Zr/Cr La/Th Cr/Ni Y/Ni

AK/DP/5 2.17 13.0 22.5 6.88 69.5 0.77 1.73 16.27 1.27

AK/DP/10 2.60 6.5 13.5 11.08 57.5 0.80 2.08 - -

AK/DP/11 2.83 8.5 14.5 12.35 97.5 0.93 1.71 26.25 1.88

AK/DP/16 3.57 6.25 13.0 12.6 53.0 0.67 2.08 17.5 1.56

AK/DP/20 2.33 3.5 10.0 20.43 44.5 0.62 2.86 14.3 1.4

AK/DP/45 3.0 2.0 6.0 29.17 53.67 0.92 3.0 - -

AK/DP/54 1.0 1.0 5.0 51.0 67.0 1.31 5.0 3.92 0.31

AK/DP/64 2.0 2.0 9.0 45.75 52.0 0.57 4.5 13.07 0.29

AK/DP/73 2.5 0.23 7.33 49.4 46.33 0.56 4.4 30.88 0.63

AK/DP/76 2.0 0.67 4.0 45.5 24.67 0.81 6.0 - -

AK/DP/89 1.0 1.0 12.0 94.0 92.0 0.98 12.0 - -

AK/BBL/12 1.5 1.5 6.5 32.33 48.0 0.99 4.33 - -

AK/BBL/47 2.5 2.5 7.5 25.0 48.5 0.78 3.0 25 1.2

AK/BBL/59 4.0 4.0 9.0 25.25 108 1.07 2.25 16.83 1.0

AK/BBL/66 1.75 3.5 12.5 20.0 34.0 0.49 3.57 17.5 0.75

RANGE 1.0-4.0 0.23-13 4.0-22.5 6.88-94 24.67-108 0.49-1.31 1.71-6.0 3.92-30.88 0.29-1.88

185

Table 7.10: Comparison of some critical elemental ratios in QPCm and quartzites

Element Ratios QPCm (N=21) Quartzites (N = 15)

Th/Sc 2.5-70 0.23-13

La/Sc 15.3-200 4.0-22.5

La/Th 0.42-6.2 1.71-6.0

Cr/Th 2.02-25 6.88-94

Cr/Ni 2.03-100 3.92-30.88

Zr/Sc 17.33-96.5 24.67-108

Y/Ni 0.36-12.4 0.29-1.88

Zr/Cr 0.24-4.18 0.49-1.31

Th/U 0.51-9.0 1.0-4.0

186

Table 7.11. Critical elemental ratios in QPCm and quartzites and comparison with different sources

* Condie (1993); $ After Taylor and Mclennan (1985); b Cullers (1994, 2000); CN- Chondrite Normalized Value, Eu/Eu*-

Europium Anomaly

Elemental ratio

Range in QPC matrix(Present

study)

Range in IOG quartzites

(Present study)

Range of sediments From felsic

sourcesb

Range of sediments from mafic sourcesb

Average Proterozoic Sandstones

*

UCC * UCC$

La/Sc 15.3-200 4.0-22.5 2.5–16.3 0.43–0.86 4.21 1.91 2.7

Th/Sc 2.5-70 0.23-13 0.84–20.5 0.05–0.22 1.75 0.71 1.0

Cr/Th 2.02-25 6.88-94.0 4.0–15.0 25.0–500 5.71 4.46 3.3

Eu/Eu* 0.06-0.28 0.33-0.54 0.40–0.94 0.71–0.95 0.67 0.59 0.61

(La/Lu)CN 7.6-42.2 - 3.0–27.0 1.10–7.00 8.07 7.21 -

187

7.1.4. REE distribution in QPCm and IOG quartzites:

REE distribution in QPCm and quartzites are tabulated in Table.7.12 and 7.13. Total

REE in QPCm ranges from 61.6-1246 ppm (average = 356.5 ppm) whereas in

quartzites it ranges from 28-235.9 ppm (average = 95.94 ppm), thus indicate

enrichment of REE in QPCm than in quartzites. Total REE content in QPCm show

enrichment compared to UCC and PAAS. On the other hand quartzites show

depletion in total REE content with respect to UCC and PAAS. Y content in QPCm

range from 5.0 to 130 ppm (average = 41.5 ppm) which is 1.5 to 2.0 times more than

their content in UCC and PAAS. On the other hand, Y concentrations in quartzites

vary from 3.0 to 28 ppm with an average of 8.6 which is about 3times lower than the

values in UCC and PAAS.

LREE (La + Ce+Pr + Nd + Sm) and HREE (Gd + Tb + Dy + Ho + Er + Tm +Yb)

ratios are indicator of provenance of the sediments. According to Cullers and Graf

(1984) high LREE/HREE ratio is present in felsic rocks whereas low LREE/HREE

ratios have been noted in mafic rocks. In the present study, both QPCm (Range 6.25-

21.57, average = 11.17) and quartzites (Range=7.31-21.5, average = 12.10) have

similar LREE/HREE ratio. This indicates enrichment of LREE/HREE ratio in QPCm

and quartzites compared to UCC and PAAS content. High LREE/HREE ratio

therefore is indicative of their felsic provenance. From this ratio, it is also evident

that although, there are variations in grain sizes of QPCm and quartzites, still they

preserve similar LREE/HREE ratios, indicates that grain size has not affected the

overall, ratio of LREE and HREE, and hence preserve the original character of the

provenance rock (Table 7.12 & 7.13).

188

Table 7.12: REE distribution in QPC (in ppm, ICP-MS data)

UCC© :Average of Upper Continental Crust (Values afterTaylor and McLennan,1985 in Akarish and Gohary,2011). PAAS® : Average of Post Archean Australian Shale(Values afterTaylor and McLennan, in Akarish and Gohary,2011).

S. No. La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu ΣREE Y LREE HREE LREE/HR

EE

DP/8 198 293 23 135 31 1.1 2.8 1.8 20 3.0 13 1.1 11 1.3 760.3 103 680 39.7 17.13

DP/81 200 317 20 130 29 1.0 25 1.4 14 3.0 7.0 0.8 5.0 1.1 754.3 82 696 56.2 12.38

DP/86 94 158 12 68 15 0.6 12 0.8 7.0 1.0 3.0 0.7 2.0 0.6 374.7 25 347 26.5 13.09

DP/90 325 534 32 224 48 0.8 37 1.7 20 3.0 11 0.6 8.0 0.8 1246 90 1163 81.3 14.31

DP/23 51 68 7.0 32 7.0 0.5 7.0 0.8 5.0 2.0 3.0 0.6 3.0 0.7 185.6 28 165 26.4 6.25

DP/2 230 406 24 162 36 0.9 30 1.4 18 3.0 10 0.5 7.0 0.9 829.7 91 858 69.9 12.27

DP/14 110 169 12 74 16 0.5 17 1.0 10 2.0 8.0 0.5 5.0 0.6 425.6 58 381 43.5 8.76

DP/28A 43 69 5.0 30 6.0 0.5 5.0 <0.5 3.0 0.5 1.0 <0.5 2.0 <0.5 165 18 153 11.5 13.30

DP/35 83 133 10 57 12 <0.5 11 0.7 7.0 0.6 5.0 <0.5 4.0 <0.5 323.3 44 295 28.3 10.42

DP/55 45 69 5.0 27 5.0 <0.5 4.0 <0.5 2.0 <0.5 1.0 <0.5 <0.5 <0.5 158 5.0 151 7.0 21.57

Bali/1 16 29 2.0 7.0 2.0 <0.5 2.0 <0.5 2.0 0.6 1.0 <0.5 <0.5 <0.5 61.6 8.0 56 5.6 10.0

Bali/8 32 39 4.0 15 3.0 <0.5 3.0 <0.5 2.0 2.0 1.0 <0.5 <0.5 <0.5 101 9.0 93 8.0 11.63

Bali/10 51 81 8.0 39 10 0.6 8.0 0.5 3.0 0.6 2.0 <0.5 0.6 0.6 205.4 10 189 14.7 12.86

BBL/41 62 103 8.0 44 9.0 <0.5 7.0 0.5 3.0 0.5 1.0 <0.5 2.0 0.5 240.5 23 226 14 16.14

BBL/52 107 186 16 82 20 0.9 19 0.7 12 2.0 10 0.5 8.0 1.0 464.1 76 411 52.2 7.87

BBL/70 76 123 10 51 10 <0.5 11 0.5 8.0 1.0 5.0 <0.5 5.0 0.5 301 46 270 30.5 8.85

BBL/74 46 80 4.0 33 8.0 <0.5 8.0 <0.5 6.0 <0.5 2.0 <0.5 4.0 0.5 189.5 39 171 20 8.55

BBL/78 31 47 1.0 21 5.0 <0.5 6.0 <0.5 2.0 1.0 1.0 <0.5 3.0 0.5 118.5 31 105 13 8.08

BBL/85 38 54 1.0 21 7.0 <0.5 5.0 <0.5 2.0 1.0 1.0 <0.5 <0.5 <0.5 130 14 121 9.0 13.44

BBL/90 27 44 2.0 18 6.0 <0.5 6.0 <0.5 2.0 1.0 1.0 <0.5 2.0 <0.5 109 18 97 12 8.08

BBL/100 82 142 10 62 14 <0.5 14 0.5 10 1.0 7.0 <0.5 0.6 0.6 343.1 54 310 33.1 9.36

Range 16-325 29-534 1.0-32 7.0-224 2.0-48 <0.5-1.1 2.0-37 <0.5-1.8 2.0-20 <0.5-3.0 1.0-13 <0.5-1.1 <0.5- 11 <0.5-1.3 61.6-1246 5.0-130 56-1193 9.0-81.3 7.87-21.57

Average 92.7 149.7 10.3 63.4 14.2 0.74 11.4 0.95 7.5 1.5 4.5 0.66 4.3 0.73 356.5 41.5 330.4 28.68 11.16

UCC© 30 64 7.1 26 4.5 0.88 3.8 0.64 3.5 0.8 2.3 0.33 2.2 0.32 146..37 22 131.6 13.57 9.70

PAAS® 38 80 8.9 32 5.6 1.1 4.7 0.77 4.4 1.0 2.9 0.4 2.8 0.43 183 27 164.5 16.97 9.69

189

Table 7.13: REE in selected IOG quartzites sample (In ppm)

UCC© :Average of Upper Continental Crust (Values afterTaylor and McLennan,1985 ). PAAS® : Average of Post Archean Australian Shale (Values afterTaylor and McLennan).

S. No La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu €REE Y LREE HREE

LREE/HREE

DP/5 45 100 3.0 34 7.0 <0.5 7.0 <0.5 4.0 0.7 2.0 <0.5 3.2 0.6 206.5 14 189 16.9 11.2 DP/10 27 50 <1 19 4.0 <0.5 4.0 <0.5 3.0 0.6 2.0 <0.5 2.3 0.5 112.4 11 100 11.9 8.40 DP/11 29 57 <1 23 5.0 <0.5 5.0 <0.5 4.0 0.8 2.0 0.5 3.3 0.7 130.3 15 114 15.6 7.31 DP/16 52 109 10 37 8.0 0.8 7.0 0.9 5.0 0.9 2.5 <0.5 2.4 0.4 235.9 28 216 18.7 11.6 DP/20 20 40 5.0 18 5.0 0.6 4.0 0.7 3.0 0.5 0.9 <0.5 0.5 <0.5 98.2 14 88 9.6 9.20

DP/45 18 44 5.0 18 5.0 0.7 4.0 0.5 3.0 <0.5 0.5 <0.5 <0.5 <0.5 98.7 6.0 90 8.0 11.3 DP/54 5.0 13 1.0 6.0 1.0 <0.5 1.0 <0.5 1.0 <0.5 <0.5 <0.5 <0.5 <0.5 28 4.0 26 2.0 13.0

BBL/12 13 31 4.0 12 2.0 <0.5 2.0 <0.5 2.0 <0.5 <0.5 <0.5 0.5 <0.5 66.5 4.0 62 4.5 13.8 BBL/47 15 27 3.0 11 2.0 <0.5 2.0 <0.5 1.0 <0.5 <0.5 <0.5 0.5 <0.5 61.5 6.0 58 3.5 16.6

BBL/59 9.0 19 2.0 7.0 1.0 <0.5 2.0 <0.5 2.0 <0.5 <0.5 <0.5 <0.5 <0.5 42 6.0 38 4.0 9.50

BBL/66 25 45 5.0 15 4.0 0.7 4.0 0.5 3.0 0.5 1.3 <0.5 0.8 <0.5 104.8 6.0 94 10.1 9.31 DP/64 18 32 4.0 13 2.0 <0.5 2.0 <0.5 2.0 <0.5 <0.5 <0.5 <0.5 <0.5 73 4.0 69 4.0 17.3

DP/73 22 41 5.0 15 3.0 0.5 3.0 <0.5 2.0 <0.5 0.8 <0.5 <0.5 <0.5 92.3 5.0 96 5.8 16.6 DP/76 12 20 2.0 7.0 1.0 <0.5 1.0 <0.5 1.0 <0.5 <0.5 <0.5 <0.5 <0.5 44 3.0 42 2.0 21.0 DP/89 12 19 2.0 8.0 2.0 <0.5 1.0 <0.5 1.0 <0.5 <0.5 <0.5 <0.5 <0.5 45 3.0 43 2.0 21.5 Range 5.0-52 13-109 <1.0-10 6.0-37 1.0-

8.0 <0.5-0.8

1.0-7.0 <0.5-0.9 1.0-5.0

<0.5-0.9

<0.5-2.5

<0.5-0.5

<0.5-3.3

<0.5-0.7

28-235.9

3.0-28

26-216

2.0-18.7

7.31-21.5

Average 21.8 43.13 3.4 16.2 3.46 - 3.26 - 2.46 - - - - - 95.94 8.6 21.7 7.9 12.1 UCC© 30 64 7.1 26 4.5 0.88 3.8 0.64 3.5 0.8 2.3 0.33 2.2 0.32 146.37 22 131.6 13.57 9.70

PAAS® 38 80 8.9 32 5.6 1.1 4.7 0.77 4.4 1.0 2.9 0.4 2.8 0.43 183 27 164.5 16.97 9.69

190

Table 7.14: Total RE2O3 content in detrital grains in QPC matrix.

7.1.5. Relation between Al2O3 versus major oxides in QPCm and IOG quartzites:

In order to decipher the relation of major oxides with Al2O3, all major oxides of

QPCm and quartzites have been plotted against Al2O3. It is generally seen that most

of the trace elements and REE are associated with fine grain sediments mainly with

clay or Al2O3. In IOG quartzites, Al2O3 shows positive relation with all oxides except

SiO2, CaO and Na2O.Strong negative correlation of SiO2 with Al2O3 (-0.99)

(Fig.7.3a) indicates that most of the silica is present as quartz grains. Low Al2O3/SiO2

(0.012-0.078) and high SiO2/Al2O3 (12.89-86.36, average = 19.88) also confirm

quartz enrichment in quartzites from study area. All other oxides like TiO2 (+0.54)(

Fig.7.3a), K2O (+0.96), P2O5 (+0.42), Fe2O3(T)(+0.69), and MgO(+0.43) show

positive correlation with Al2O3 (Fig.7.3b) implying that these elements are

associated with either micaceous or clay minerals. K2O (+0.96) show very strong

positive correlation with Al2O3 indicating that almost all potash in quartzite is

associated with alumina.

Minerals RE2O3 (Range, in Wt %)

Average (Wt %)

Monazite 58.62-61.00 59.63

Zircon 0.36-1.28 0.63

Uraninite 1.57-2.23 1.83

191

Fig.7.3b. Relation between Al2O3 with other major oxides in IOG quartzites, western margin of Bonai granite, Sundergarh district, Orissa.

Fig.7.3a. Relation between Al2O3 with other major oxides in IOG quartzites, western margin of Bonai granite, Sundergarh district, Orissa.

192

In case of QPCm, Al2O3 shows negative correlation with SiO2(-0.77), Fe2O3(T)(-

0.46), CaO(-0.33), MgO(-0.16) and P2O5(-0.12) (Fig.7.4) positive correlation with

K2O(+0.95), Na2O(+0.33) and TiO2(+0.16), thus indicating that potash and partly

soda and titanium are associated with alumina or clay or aluminosilicates like

sericite, biotite, muscovite and silica is present as quartz grains, Fe as goethite,

magnetite, ilmenite, rutile, anatase and Mg associated with chlorite.

Fig.7.4. Relation between Al2O3 with other major oxides in QPC, western margin of Bonai granite, Sundergarh district, Orissa.

193

7.1.6. Relation between Al2O3 and Trace elements in QPC and IOG Quartzites:

This has been observed that most of REE and trace elements are associated with clay

minerals in clastic sedimentary rocks (Asiedu et al., 2000). To know the content of

various trace elements association in clastic sediments, binary plots of different trace

elements with Al2O3 have been attempted.

QPCm : Plot of Al2O3 versus other trace elements in QPCm indicate positive

correlation of Al2O3 with Rb (+0.93), Ga (+0.81), K(+0.95), Ba(+0.68), Sc (+0.47)

and negative and weakly positive correlation with Cu, Co, Ni, Fe2O3, Cr, Pb, Th, U in

QPC(Fig.7.5). Strong positive relation of Al2O3 with Ba, Ga, Rb and K suggest that

all these elements are associated with clay fractions in QPC. Strong positive

correlation between K and Ga (+0.75), Rb (+0.95) and Ba (+0.73) and all these

elements with Al2O3 are suggestive of their control by clay minerals in QPC

(Fig.7.5).

Negative and very low positive correlation of Al2O3 with other elements are

indicative of their discrete mineral phase/s like chromite, pyrite for Ni, Co, Cu;

galena and uraninite for Pb, and uraninite for U and Th and monazite for mainly Th

and minor U and REE which is also supported by their identification by petrographic

observations and SEM-EDS and EPMA studies. Strong and positive correlation of

TiO2 with all REE in QPC suggests that titanium bearing minerals are also good

carrier for rare earth elements.

On the contrary, Al2O3 shows positive correlation with all trace elements in IOG

quartzites pointing thereby that all trace elements are linked with clays in quartzites

(Fig.7.6).

194

Fig.7.5. Relation between Al2O3 and trace elements in QPCm

195

Fig.7.6. Relation between Al2O3 and important trace elements in IOG quartzites.

196

7.1.7. Relation between Al2O3 and REE in QPCm and IOG Quartzites:

Major proportion of REE is generally incorporated in the finer fractions of rocks and

it is known that trivalent REE can easily be accommodated in the clay minerals

(Asiedu et al., 2000). In order to verify this observation, all REE and also total REE

were plotted against Al2O3 (indicative of clay minerals in sediments).

In case of QPCm, all REE show negative correlation with Al2O3 indicating that REEs

are not associated with clay fractions in QPC and appears to be present as discrete

mineral phase (Fig. 7.7). Presence of monazite, uraninite, zircon, chromite, sphene,

rare allanite is the main carrier of REE in QPC. Monazite shows enrichment in total

REE varying from 58.62 to 61.0 % in QPCm (Table 7.14).

Fig.7.7. Relation between Al2O3 and REE in QPC, western margin of Bonai granite, Orissa.

197

Al2O3 has positive correlation with almost all REE in IOG quartzites, thereby

indicating that all REEs are associated with Al2O3 in quartzites (Fig.7.8).

Fig.7.8. Relation between Al2O3 and REE in IOG quartzites, western margin of Bonai granite, Orissa.

198

7.1.8. RELATION BETWEEN Al2O3 AND TOTAL REE: From Fig.7.9a and b, it

is evident that Al2O3 has negative correlation with total REE in QPC (Fig.7.9a)

whereas in IOG quartzite Al2O3 shows moderate but positive correlation with Total

REE (Fig.7.8b) thereby suggesting that in IOG quartzites, all REE are associated with

alumina or clay minerals whereas in QPC they are independent and REE forms its

discrete mineral phases which has been identified as mainly monazite, uraninite,

chromite, ilmenite, rutile, rare xenotime, allanite and sphene. Electron Microprobe

study has indicated 58.62 to 61.0 % total RE2O3 in monazite, 0.36 to 1.28 % in

zircon and 1.57 to 2.23 % in uraninite in QPCm ( Table.7.14).

Fig.7.9a.Al2O3 and Total REE in QPC, western margin of Bonai granite, Orissa.

Fig.7.9b. Al2O3 and Total REE in IOG quartzites, western margin of Bonai granite.

199

7.1.9. Spatial variation of trace elements in QPCm and IOG Quartzites: (i) Variation in trace element in QPCm : The trace element content in QPCm of various

locations along western margin of Bonai granite are tabulated in Table 7.14a. Spatial

distribution of various trace elements in QPCm indicate highest value of both Th and U

near Birtola and lowest values around Bagiyabahal area. PhuljhoriPahar QPC indicated

Values of Th and U in between Birtola and Bagiyabahal QPC. Similarly, highest value of

Cr has been shown in Birtola QPC and lowest in Phuljhori Pahar. Highest Pb value has

been noted in PhuljhoriPahar QPC and lowest in Bagiyabahal. From Table 7.14a , it is

evident that Birtola QPC are enriched in all trace elements including V, Cr, Co, Ni, Cu, Rb,

Ba, Sr, Zr and also Th, U and REE like La and Ce compared to other QPC occurrences

along western margin of Bonai granite Pluton in Orissa. Thus, it can been inferred that

QPC from western margin of BGP show some sort of spatial variations in various trace

element concentration including those of Th,U and REEs like La and Ce (Fig.7.9c).

Table 7.14a : Trace element distribution in QPCm (in ppm)

Trace Elements Bagiyabahal (n= 8) Birtola (n=7) PhuljhoriPahar(n=6) V 35 55 21 Cr 204 373 173 Co 66 75 66 Ni 12 66 21 Cu 17 57 35 Rb 29 43 32 Ba 41 75 30 Sr 4 8 5 Pb 36 107.86 134 Zr 105 166 73 La 58.62 172.57 62.67 Ce 97.37 277.86 60 Th 23.35 76.86 41.17 U 9.87 69.71 41.67

(ii) Variation in trace element in IOG Quartzites: From Table 7.14b and Fig.7.9d, it is

seen that almost all trace elements (Except Zr and Rb) have higher concentration in

quartzites of Birtola-PhuljhoriPahar as compared to those from Bagiyabahal. It means that

trace elements show increasing trend from SW to NE in the study area.

The locations of samples of both QPC and IOG quartzites taken for geochemical studies are given in Figs. 7.9e, 7.9f and 7.9g.

200

Table 7.14b . Trace elements in IOG quartzites from western margin of Bonai granite (in ppm).

Trace Elements Bagiyabahal (n= 8)

Birtola-PhuljhoriPahar (n= 7)

Cr 115.75 166.54 Ni 5.37 8.36 Cu 7.75 10 Rb 54.18 36.5 Ba 118.75 211.82 Pb 5 19.91 Zr 192.25 126.09 La 15.5 23.64 Ce 30.5 47.73 Th 4.75 9.72 U 2.25 3.82

Fig. 7.9c. Distribution pattern of trace elements in QPCm at various locations along western margin of Bonai granite.

Fig.7.9d. Distribution pattern of trace elements in IOG quartzites at various locations along western margin of Bonai granite.

201

Fig. 7.9e. Geological map of Bagiyabahal area showing locations of QPC and quartzite samples for its geochemical study.

Fig.7.9f. Geological map of Birtola area area showing locations of QPC and quartzite samples for its geochemical study.

Fig.7.9g.Geological map of PhuljhoriPahar showing locations of QPC and quartzite samples for its geochemical study.

202

7.2. Geochemical Classification of QPC matrix (QPCm) and IOG Quartzites

Sedimentary rocks particularly clastic rocks are classified based on their major element

chemistry. Pettijohn et al. (1972) have proposed a classification scheme of sandstones

based on their K2O and Na2O ratio. Based on this diagram, the matrix of conglomerate and

IOG quartzite, both of which are sandstone in composition petrographically occupy the

field of arkose (Fig.7.10a). Although, no feldspar grain has been observed under

microscope, this arkosic nature is due to predominace of K-bearing minerals like sericite,

biotite, and few muscovites in the matrix part. Pettijohn et al. (1972) also proposed a

chemical classification of clastic sedimentary rocks based on their Log (SiO2/Al2O3) vs

Log (Na2O/K2O). In this diagram, QPCm occupy the field of sublitharenite to subarkose to

arkose whereas IOG quartzites are plotted in arkose to subarkose field (Fig.7.10b). Herron

(1988) proposed a new scheme of chemical classification of sandstones and shale based on

Log (SiO2/Al2O3) vs Log (Fe2O3/K2O). When QPCm and IOG quartzite data are plotted in

this diagram, QPCm falls mainly in sub-litharenite field, partly in Fe-sands and rest in

arkose to subarkose and two to three samples in quartz-arenite field. On the other hand,

IOG quartzites occupy the field of subarkose with only one sample in quartz-arenite field

(Fig.7.10c). In ternary plot of (Fe2O3t + MgO)-Na2O-K2O (Blatt et al., 1972), QPCm

indicate their ferromagnesian nature whereas IOG quartzites are potassic in nature (Fig.

7.10d).

Fig.7.10b.Chemical classification of QPCm and IOG quartzites on Log (SiO2/Al2O3) vs Log (Na2O/K2O) diagram of Pettijohn et al.(1972).

Fig.7.10a. Classification of sandstones based on K2O/Na2O ratio (after, Pettijohn et al.,1972).

203

7.3. Provenance Study for QPC and IOG Quartzites: The geochemical signatures of clastic rocks are very helpful in interpreting the

provenance characteristics (Taylor and Mclennan, 1985; Tripathi and Rajamani,

2003; Armstrong-Altrin, 2004; Mongelli et al., 2006; Osae et al., 2006; Nagarajan et

al., 2007; Chakrabarti et al., 2009; Moosavirad et al., 2012). Geochemical approach is

equally applicable to both coarse and fine grained sedimentary rocks in contrast to

petrographical approaches where provenance study for very fine grained and very

coarse grained sedimentary rocks are not possible (McLennan et al., 1993). Certain

key trace elements may be very sensitive in identifying minor components in the

rocks which are not possible by normal petrographic approach (Nelson and DePaolo,

1988).

Composition of sediments is controlled by their Provenance or source-rock

composition from which they are derived. Secondary processes like weathering,

transport, diagenesis etc. can affect the chemical composition of sediments (Cullers et

al., 1987; Wronkiewicz and Condie, 1987). Therefore, most sedimentologists rely

upon elements that are least mobile under the expected geological conditions in

deciphering the provenance character of the sediments.

Elements having short residence time in ocean are reliable indicator of provenance

(Taylor and Mclennan, 1985). Holland (1978) suggested that elements like La, Ce,

Fig.7.10c.Chemical classification of the QPC matrix and quartzites of IOG based on Log (SiO2/Al2O3) vs Log ( Fe2O3/K2O (fields after Herron, 1988).

Fig.7.10d. Fe2O3 (t)-Na2O-K2O diagram for classification of sandstone (after Blatt et al,1972).

204

Nd, Y, Th, Zr, Hf, Nb, Ti and Sc are the most suitable elements for provenance

studies because of their relative low mobility during sedimentary processes and they

have low residence time in sea water. Bhatia and Crook (1986) have shown that these

low mobility elements gets transported quantitatively into clastic sedimentary rocks

during their weathering and transport reflecting the signature of the parent rocks.

The elements like Zr, Hf, Nb, Y and Th are preferentially get partitioned into melts

during crystallization and due to this, these elements are enriched in felsic rock rather

than in mafic rocks (Feng and Kerrich,1990). Similary, REE and Sc also give

indication of source rock composition because of the similar reason mentioned above

(Bhatia and Crook, 1986). REE, Th and Sc are generally having higher abundance in

felsic whereas Sc, Cr and Co are concentrated more in mafic igneous rocks.

The Th/Sc ratio is a measure of contribution of felsic/mafic rocks in the source area.

Th is incompatible and is expected more in younger and more differentiated felsic

crust while Sc which is a compatible element is generally expected to be more in the

early formed and less differentiated mafic crust (Taylor and McLennan, 1985).

Viewed in this light, REE and Th concentrations are very high in QPCm, thus

indicating its derivation from felsic igneous source rocks. Low Sc (<1.0-4.0 ppm,

average = 2.07 ppm, n = 21) and high Th/Sc ratio further support this observation for

QPCm. In quartzites, concentration of both Th and Sc are low compared to QPCm,

but their Th/Sc ratio is 0.23 to 13, indicating their derivation from both felsic and

minor mafic component in the provenance (Tables 7.3, 7.4, 7.8 and 7.9).

Th/Sc ratios plotted against Sc are more sensitive to provenance composition than

REE (Fedo et al., 1997a). In the Fig.7.11, all QPCm samples plot above Th/Sc = 1.0

line around the field of Archean granite and cratonic sandstone values. IOG

quartzites also plot nearby granite and sandstone field except two samples which falls

below Th/Sc less than 1.0 value. Thus, Th/Sc vs Sc binary diagram strongly support

that the QPCm and quartzites in the study area were mainly derived from felsic rocks

rather than mafic provenance.

Th/Sc ratio is generally more than 1.0 in felsic rocks and in mafic rocks; this ratio is

about 0.6 or less (Chakrabarti et al., 2009). In the present study area, in QPCm Th/Sc

205

ratio is more than 1.0 in all samples, whereas in IOG quartzites, majority of the

samples show Th/Sc ratio >1.0, but two samples have Th/Sc ratio 0.23 and 0.67.

Thus, it may be interpreted that QPCm fall in the range of continental rocks signature

whereas IOG quartzites show mainly continental but two samples show inclination

towards mafic rock signature, but overall, continental signature is dominant in the

area.

The triangular plot of La-Th-Sc is very useful in getting information about the source

rock composition (McLennan and Taylor, 1985; Cullers, 2002), La, Th and Sc data

were of QPCm and quartzites were plotted in La-Th-Sc ternary diagram (Fig.7.12).

From this, it is clear that both QPCm and quartzites occupy the area around the field

of granite and sandstone, generally plotted along La-Th line and away from Sc corner

and field of basalt, andesite and komatiite,thus supporting the prevalence of felsic

rock in the provenance which have provided detritus to QPC-quartzite along western

margin of Bonai granite in Orissa.

La/Th vs Hf diagram is also used to differentiate between different source

compositions of sediments (Floyd and Leveridge, 1987). The data on QPCm and

quartzites plotted on La/Th vs Hf diagram, most of samples plot near felsic and

mixed felsic-mafic provenance (Fig.7.13).

Floyd et al. (1989) proposed a bivariate plot of TiO2 wt % vs Ni (ppm) to evaluate

provenance composition of siliciclastic sedimentary rocks. On this bivariant diagram,

both QPC and quartzites from the study area plot nearby the field of acidic rock

(Fig.7.14).

206

Fig.7.13. Hf vs La/Th sedimentary provenance discriminant diagram (Floyd and Leveridge,1987).

Fig.7.14. TiO2 vs. Ni sedimentary provenance discriminant diagram for the QPCm and IOG quartzites, fields for acidic and basic source materials after Floyd et al. (1989).

Fig.7.12.La-Th-Sc diagram for QPC and quartzites. UCC (Mclennan, 2001) and Sandstone, andesite, basalt and komatiite (Condie, 1993).

Fig.7.11. Th/Sc vs Sc plot for QPC and quartzites. UCC (Mclennan, 2001) and Sandstone, andesite, basalt and komatiite (Condie, 1993).

207

Discriminant function scores plot based on major element chemistry has been utilized

in provenance study of sedimentary rocks. Discriminant function scores of major

element data is helpul in separation of sedimentary rock provenance into four groups

namely, magic igneous, intermediate igneous, felsic igneous and quartzose

sedimentary by Roser and Korsch (1988). Data on discriminant function scores of

both QPCm and quartzites plot in quartzose sedimentary provenance field which

represents recycled mature polycyclic quartzose detritus. Recycled sources represent

quartzose sediments of mature continental provenance, and the derivation of the

sediments could be from a highly weathered granite-gneiss terrain and/or from a pre-

existing sedimentary terrane (Fig.7.15). Both QPCm and quartzites samples fall near

the values of average Proterozoic sandstone field of Condie (1993) in discriminant

function diagram (Fig.7.15).

Fig.7.15. Sedimentary provenance discriminant diagram. Plot of function F1 and F2 for the QPCm and quartzites. Provenance fields are after Roser and Korsch (1988). Upper Continental Crust (open circle) and average Proterozoic sandstone (open square); Data from Condie (1993). Discriminant Function-1—(-1.773 TiO2) + 0.607 Al2O3 + (0.760 Fe2O3 T) + (-1.500 MgO) + (0.616 CaO) + (0.509 Na2O) + (- 1.224 K2O) + (-9.090). Discriminant Function 2-- (0.445 TiO2) + (0.070Al2O3) + (-0.250 Fe2O3 T) + (-1.142 MgO ) + (0.438 CaO) + (1.475 Na2O) + (- 1.426 K2O) + (-6.861).

208

Al and Ti are considered chemically immobile constituents of weathering profile,

sediments and sedimentary rocks (Maynard, 1992) and hence may be used as

provenance indicator (Young and Nesbitt, 1999). Al2O3/TiO2 ratio is used to infer the

source rock characteristics of clastic sedimentary rocks (after McLennan et al., 1980).

This ratio shows variation from 3-8 in mafic igneous rocks, 8-21 in intermediate

rocks, 21 to 70 in felsic igneous rocks and 15 to 25 in both shales and sandstones of

Precambrian age reported from Egypt (Willis et al.,1988). Al2O3/TiO2 ratio for QPC

and quartzites vary from 2.49-34.50(average = 7.77) and 11.46-753 (average = 23.58)

respectively in the study area which is indicative of their granitic provenance

(Amajor, 1987; Moosavirad et al., 2012).

During the chemical weathering, Al and Ti are generally stable or residual elements;

K and Mg are fixed in clay minerals whereas Ca is preferentially leached out (Nesbitt

et al., 1980). The SiO2/MgO ratio varies from 65.67-2210.50(Average = 222.24) in

QPCm and from 134.57-672.38 (Average = 269.94) in case of IOG quartzites. High

SiO2/MgO ratios and high SiO2 (Average = 90.80 Wt % in QPCm and 89.08 Wt % in

quartzites) and moderate abundances of Al2O3 (1.45-7.56 Wt % in QPCm and 1.13-

6.53 Wt % in quartzites) suggest predominantly felsic source compositions in the

provenance ( Saxena and Pandit,2012). The ferromagnesian trace elements like Ni,

Cr and V are generally abundant in mafic and ultramafic rocks and their enrichment

in sedimentary rocks therefore may be indicative of the presence of these rocks in

provenance area (McLennan et al., 1993).

Higher Cr and low V in both QPCm and quartzites indicate the presence of some

albeit minor contribution of chromite among the heavy minerals. The Cr/Th ratio, a

good indicator for provenance (Condie and Wronkiewicz 1990). Cr/Th ratios in

QPCm (2.02-25) and quartzites (6.88-94) (Table.7.10) in the study area indicate

presence of some ultramafic rocks in the provenance.

209

Y/Ni ratios are also indicator of abundance of mafic and ultramafic rocks in the

provenance (McLennan et al., 1993). Y/Ni ratios are found to be varying from 0.36-

12.4 in QPCm and 0.29-1.88 in quartzites (Tables 7.8, 7.9 and 7.10), thus indicating

some contribution from mafic and ultramafic rocks from the provenance area.

The data on critical elemental ratios like Th/Sc, La/Sc, Th/Cr, Eu/Eu* in QPCm and

IOG quartzites were compared with various sources like Upper Continental Crust

(UCC), sediments from felsic and mafic sources, average Proterozoic sandstones,

granite, andesite and opiolites, both QPC and quartzites show very high La/Sc and

Th/Sc ratios compared to mafic, andesite and ophiolitic sources and enrichment over

values from sediments of felsic sources, granite, UCC and Proterozoic

sandstones(Table 7.15).

Similarly, Cr/Th ratios in QPC and quartzite from the study area indicate enrichment

with respect to sediments from felsic sources, granite, UCC, lower than ophiolite but

within the range of sediments from mafic sources.Eu/Eu* ratio are near the range of

granite source but lower than mafic sources( Table 7.15). All these comparisons

indicate derivation of QPC and quartzites in the study area mainly from felsic and

granitic sources and very minor input if any from mafic provenance

210

Table 7.15: Critical elemental ratios in QPC and quartzites and comparison with different sources

Elemental ratio

Range in QPC matrix (Present study)

Range in IOG quartzites (Present study)

Range of sediments from felsic sources

(Cullers,19

94, 2000)

Range of sediments from mafic sources

(Cullers,

1994, 2000)

Average Proterozoic Sandstones

(Condie, 1993)

UCC (Condie ,1993)

UCC Taylor and Mclennan (1985)

Granite (Condie ,1993)

Andesite (Condie, 1993);

La/Sc 15.3-200 4.0-22.5 2.5–16.3 0.43–0.86

4.21 1.91 2.7 8.0 0.90

Th/Sc 2.5-70 0.23-13 0.84–20.5 0.05–0.22

1.75 0.71 1.0 3.57 0.22

Cr/Th 2.02-25 6.88-94.0 4.0–15.0 25.0–500

5.71 4.46 3.3 0.44 9.77

Eu/Eu* 0.06-0.28 0.33-0.54 0.40–0.94 0.71–0.95

0.67 0.59 0.61 0.37 0.66

(La/Lu)N 7.6-42.2 - 3.0–27.0 1.10–7.00 8.07 7.21

211

7.4. REE in Provenance Study: REE concentration in clastic sediments reflect the provenance and has been used to

infer source rock characterization( McLennan,1984) because of their relatively low

mobility during weathering, transport, diagenesis, and metamorphism. They are

transported chiefly as particulate matter and reflect the chemistry of their source

rocks. The REE patterns have been also used to infer sources of sedimentary rocks,

since basic rocks contain low LREE/HREE ratios and no Eu anomalies, whereas

more silicic rocks usually contain higher LREE/HREE ratios and negative Eu

anomalies (Cullers and Graf, 1983). Therefore, the REE patterns of the source rocks

may be preserved in sedimentary rocks (Taylor and McLennan, 1985; Wronkiewicz

and Condie, 1987, 1989). The Eu anomaly in sedimentary rocks is usually interpreted

as being inherited from igneous source rocks (McLennan and Taylor, 1991; Taylor

and McLennan, 1985).

To get the information about the source rock for QPC and quartzites in the study

area, chondrite normalized REE plots were plotted for these rocks. The REE plots for

QPC and quartzites have been shown in Fig.7.16a,b and Fig.7.17a,b respectively.

(i) REE pattern indicates LREE enrichment and almost flat HREE pattern in

QPCm (Fig.7.16a,b) compared to IOG quartzites which shows fractionated gentle

sloping REE pattern with low REE and depleting trend in HREE (7.17a and b) .

(ii) LREE enrichment is due to presence of monazite grains in QPCm which was

observed petrographically and also supported by mineral chemistry.

(iii) Both QPC and quartzite show fractionated pattern (La/Yb)n 5.77-31.93 in QPC

and 14.71-99.18 for quartzites (Table 7.16).

(iv) Moderate to strong negative Eu anomaly (0.06-0.28) in QPC and moderate

negative Eu anomaly (0.33-0.54) in IOG quartzites (Table 7.16).

(v) LREE enrichment in QPC and quartzites are indicated by high values of

La(/Sm)CN values ranging from 3.18-4.55 in QPC and 1.87-9.12 in quartzites and

nearly flat HREE pattern with (Gd/Yb)CN ranging from 1.08-4.85 in QPC.

212

The presence of negative Eu anomaly has been attributed to the presence of Eu-

depleted felsic igneous rocks in the provenance such as granites. QPC is generally

characterized by significant depletion of Eu in chondrite- normalised REE pattern,

higher concentration of total REE and increase in Th/Sc (Bhushan and Sahoo, 2010).

High content of Th, U, La together with fractionated Chondrite normalized REE

pattern and negative Eu anomaly suggest granitic provenance for QPC-quartzite

sequence in the study area.

1.00

10.00

100.00

1000.00

La Ce Pr Nd Sm Eu Gd Tb Dy Er Yb

AK/DP/16AK/DP/20AK/DP/28AK/DP/45AK/BBL/66AK/DP/32AK/DP/73Average

1.00

10.00

100.00

1000.00

La Ce Pr Nd Sm Eu Gd Tb Dy Er Yb

Average

Fig.7.17a. Chondrite normalized REE pattern of IOG quartzites from western margin of Bonai granite, Sundergarh district of Orissa (Chondrite values after McDonough & Sun, 1995).

Fig.7.17b. Average REE pattern of IOG quartzites from western margin of Bonai granite, Sundergarh district of Orissa (Chondrite values after McDonough & Sun,1995).

1.00

10.00

100.00

1000.00

La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu

Average

Fig.7.16b. Average REE pattern of QPCm from western margin of Bonai granite, Sundergarh district of Orissa (Chondrite values after McDonough & Sun, 1995).

Fig.7.16a. Chondrite normalized REE pattern of QPCm from western margin of Bonai granite, Sundergarh district of Orissa (Chondrite values after McDonough & Sun,1995).

1

10

100

1000

10000

La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu

Dp/8DP/81DP/86DP/90DP/23DP/2DP/14DP/28ABali/10BBL/52Average

213

Table 7.16: Comparison among various chondrite normalized REE ratios in QPCm and quartzites

7. 5. Sediment Sorting and Recycling:

Transportation and deposition of sediments involve mechanical sorting. It affects

chemical composition of sedimentary rocks (Mongelli et al., 2006). During this

process mainly Al2O3 (clay) gets fractionated from SiO2 (quartz and feldspar), and

TiO2 (Ti present in clays and as Ti-Oxides) from Zr (Zr present in zircon). Since most

of the Hf is associated with Zr, in the ternary diagram Al2O3- TiO2- Hf after Murphy

(2000), instead of Zr, Hf is taken into consideration. In this diagram, most of the

samples are plotted away from Al2O3 corner and slightly away from TiO2 corner,

indicating moderate enrichment of Zr in the QPC and quartzites of study area

(Fig.7.18). Zr enrichment during sorting can also be evaluated when Zr/ Sc ratio

which is a useful index of sediment recycling (Hassan et al.,2000 in Mongelli et

al.,2006) against the Th/Sc ratio and indicator of chemical differentiation (McLennan

et al.,1993). The Th/Sc–Zr/Sc variation diagram is useful in assessing the

contribution of pre-existing sources.

A Th/Sc ratio >1 of sedimentary rocks indicate input from fairly evolved crustal

igneous rocks (Taylor and McLennan,1985) whereas Th/Sc ratio <0.8 is an indication

of source other than the typical continental crust, probably a mafic source or input

from mature or recycled source if coupled with higher ratio of Zr/Sc (>10). All the

samples of QPC and IOG quartzites exhibit values of Th/Sc > 1 and Zr/Sc >

10(except three). A felsic and recycled source for these QPC-quartzites is indicated

REE chondrite normalized

ratios

QPCm(Range) Average IOG quartzites (Range)

Average

(La/Yb)n 5.77-31.93 16.79 14.71-99.18 43.12

(La/Sm)n 3.18-4.55 4.04 1.87-9.12 5.58

(Ce/Yb)n 3.54-20.75 10.51 11.92-77.63 32.86

(Gd/Yb)n 1.08-4.85 2.67 2.36-16.18 7.42

(La/Lu)n 7.6-42.2 18.5 - -

Eu/Eu© 0.06-0.28 0.14 0.33-0.54 0.43

214

by values of Th/Sc and Zr/Sc ratios (Fig.7.16). In the Zr/Sc vs Th/Sc diagram, QPC

and quartzites from the study area plot above Th/Sc ratio of 1.0 and Zr/Sc ratio of 10

( Except three quartzite samples plot below Th/Sc ratio of 1.0)( Fig.7.19).

Fig.7.19 show trend towards granite composition and few data show inclination

towards zircon addition or recycling of sediments. Thus the plot indicate moderate

enrichment of heavy mineral like zircon and hence moderate rate of recycling and

sorting of sediments during the transportation and deposition of QPC- quartzite

sequence along western margin of Bonai granite in Orissa of eastern India.

Fig. 7.18. Al2O3-Hf-TiO2 diagram (Murphy, 2000).

Fig.7.19. Th/Sc vs Zr/Sc plot (after McLennan et al., 1993) for QPCm and IOG quartzites from western margin of Bonai granite, Orissa.

215

7.6. Paleo-Weathering of QPC- IOG Quartzite Sequence: Geochemical processes such as weathering and soil formation are dominated by

alteration of feldspars (and volcanic glass), which accounts for 70% of the upper

crust if the relatively inert quartz is discounted (Nesbitt and Young, 1982, 1984).

Feldspars are by far the most abundant labile minerals, and consequently, the most

important process during silicate weathering of the earth’s upper crust is the

degradation of feldspars by aggressive soil solutions so that the proportion of alumina

to alkalis typically increases in the weathered product. The weathering history of the

provenance or source –rock can be deduced from the quantitative measurement of

chemical weathering of silicates by calculated values of Chemical Index of Alteration

(CIA) and Plagioclase Index of Alteration (PIA) (Nesbitt and Young, 1982; Fedo et

al., 1995; Akarish and Gohary, 2011).

Chemical Index of Alteration (CIA)

The Chemical Index of Alteration (CIA) is the most accepted and widely used

chemical index to determine the source-area or provenance weathering. Past

conditions of physical and chemical weathering can be reliably inferred by CIA.

Exposed rocks are affected to variable degrees by a combination of chemical and

physical weathering. Progressive chemical weathering of labile minerals like feldspar

leads to the loss of Ca2+, K+ and Na+ and the transformation to minerals more stable

under surface conditions ( Fedo et al., 1995). Ultimately, it results in the formation of

shales rich in clay minerals like illite and kaolinite, and Fe-oxyhydrates like goethite.

Physical weathering, in turn, leads to the degradation of rocks to smaller grain sizes,

ideally without causing geochemical and mineralogical changes. CIA represents a

ratio of predominantly immobile Al2O3 to the mobile cations Na+, K+ and Ca2+ given

as oxides. The CIA is defined as:

*CIA = 100(Al2O3 /Al2 O3 + CaO + Na2 O + K2O;

Where the amount of CaO incorporated in the silicate fraction of the rock. The

resultant CIA gives a measure of the proportion of secondary aluminous clay

minerals to primary silicate minerals such as feldspars (Nesbitt and Young 1982;

Young et al. 1998).

Unweathered igneous rocks have CIA values close to 50, whereas intensely or highly

weathered residual rocks have values approaching 100 due to formation of kaolinite

216

and gibbsite (Nesbitt and Young 1982). Weathering of average granodiorite or upper

continental crust (UCC) will result in the transformation of labile components

including the feldspars first to illite thus causing the sample’s composition to plot

closer to the A-K join and the illite composition in A-CN-K space (Nesbitt and

Young, 1984). Increasing formation of kaolinite during progressive weathering will

curve the weathering trend towards the A apex when approaching the A-K join

(Nesbitt and Young, 1984 in Heinrich Bahlburg, 2009).

Several workers have used CIA to decipher degree of weathering in Precambrian

pelitic rocks (Wronkiewicz and Condie, 1989). Maynard et al. (1991) was the first to

apply CIA technique to infer weathering in sand-sized clastic rocks, mainly on

Witwatersrand quartzites. This method provides useful information if comparative

data on modern sands are available as long as Al2O3 content is greater than 1.0%. In

the present study area, Al2O3 content is higher than 1.0% in both QPCm and IOG

quartzites; hence CIA method can be utilized for inferring the degree of weathering

in them.

It has also been observed by Maynard et al. (1991) that in Witwatersrand basin which

host QPC type Au-U deposit, grade of both uranium and gold increases with

increasing quartz content and therefore, the process responsible for enrichment of

quartz in the sediments were responsible for uranium stability. Thus, paleo-

weathering study will be helpful in knowing the conditions of deposition of

sediments and in turn, preservation of detrital uraninite and pyrite in them.

The degree of chemical weathering is a function of mainly climate and erosion rate,

the latter in turn varies with the rate of tectonic uplift. Generally, little tectonic uplift

in tropical climatic regions show extreme depletion of Na, Ca and Sr whereas active

tectonic uplift exhibit less depletion of these elements as in Ganges River in India

(Wronkiewicz and Condie,1987).

For the reason outlined above, The CIA values on 21 samples of QPCm and 15

quartzites were calculated based on the given formula. The CIA values for QPCm

and quartzites are given in Table.7.7.17. CIA values for QPCm range from 68.04 to

217

79.46 (average =74.92) and for quartzite this value show variation from 64.54 to

82.47 (average = 76.12). It can be suggested based on CIA values that QPC and

quartzites in the study area has undergone moderate to high degree of chemical

weathering which is lower than the CIA values calculated for Witwatersrand

quartzites ( around 80 %) but higher than the CIA values for sediments of Ganges

and Brahmaputra which are about 68 and 73 % respectively (Maynard et al., 1991).

CIA value of 100 represents the highest degree of weathering. Illite is between 75

and about 90, muscovite at 75, the feldspars at 50. Fresh basalts have values between

30 and 45, fresh granites and granodiorites of 45 to 55 (Nesbitt and Young, 1982;

Fedo et al., 1995).

In A-CN-K ternary plot (Fig.7.20), majority of the QPC and quartzite samples cluster

along the A-K join nearby illite-muscovite. Few samples occupy the central part of

triangle and more towards A- apex and only quartzite sample occupy the space along

A-CN line. In the A-CN-K diagram, weathering trend of granite, granodiorite and

tonalite have been shown with arrow starting from base of plagioclase-K-feldspar

line. These trend line and plotted points on A-CN-K diagram are traced back, they

provide the information about the source rock of the sediments and sedimentary

rocks. Viewed in this light, majority of samples indicate the granite source, few

samples between granite and granodiorite and also between granodiorite and tonalite

while rare samples near tonalite and plagioclase-kaolinite field (Fig.7.20).

218

Table 7.17: Chemical Index of Alteration (CIA) and Plagioclase Index of Alteration (PIA) for QPCm and IOG quartzites

S.No. QPC Matrix IOG Quartzites

CIA = A

/(ACNK)*100

PIA=A-K/(CAN-K)*100

Sample No CIA = A

/(ACNK)*100

PIA=A-K/(CAN-K)*100

DP/8 74.75 94.74 AK/DP/5 76.81 91.41

DP/81 75.27 82.15 AK/DP/10 76.18 92.80

DP/86 78.34 89.54 AK/DP/11 77.14 94.62

DP/90 79.46 85.12 AK/DP/16 75.77 96.48

DP/23 73.70 91.54 AK/DP/20 77.20 96.50

DP/2 74.15 79.60 AK/DP/45 78.64 93.77

DP/14 75.79 94.85 AK/DP/54 82.47 88.04

DP/28A 75.15 91.42 AK/DP/64 76.86 88.40

DP/35 78.48 94.73 AK/DP/73 75.84 88.88

DP/55 76.95 87.50 AK/DP/76 78.79 92.17

Bali/1 75.99 88.89 AK/DP/89 74.47 81.98

Bali/8 72.73 84.18 AK/BBL/12 77.22 92.15

Bali/10 70.07 79.29 AK/BBL/47 72.66 82.07

BBL/41 68.04 83.39 AK/BBL/59 64.54 65.29

BBL/52 76.96 97.35 AK/BBL/66 77.22 90.05

BBL/70 72.90 92.97 - -

BBL/74 72.80 91.14 - -

BBL/78 73.19 92.15 - -

BBL/85 75.33 94.64 - -

BBL/90 73.95 92.62 - -

BBL/100 75.33 94.55 - -

Average 74.92 89.64 76.12 88.97

219

Fig.7.20. A-CN-K ternary diagram, Al2O3–CaO* + Na2O–K2O (after Nesbitt and Young, 1982); CaO* = CaO in silicate phase. Data on granite, granodiorite, tonalite and Archean upper crust are from Condie(1993). Arrow is trend of weathering.

Fig.7.21. (A-K)-C-N ternary plots for both QPC matrix and IOG quartzites alteration.

220

The geology of Singhbhum-Orissa Craton exposes different types of granitic rocks

ranging from granite to tonalite south of the study area which might have provided

the detritus to these sediments during the upliftment, erosion and moderate rate of

chemical weathering.

Plagioclase Index of Alteration (PIA): The degree of chemical weathering can also

be estimated by using PIA (Fedo et al.,1995) in molecular proportions , the PIA

formula is:

PIA = (Al2O3-K2O)/(Al2O3 + CaO* + Na2O- K2O)x100, where CaO* is CaO only

residing in the silicate fractions.

Plagioclase Index of Alteration (PIA), which is based on the assumption that

plagioclase is quite abundant in silicate rocks and dissolves relatively rapidly (Fedo et

al., 1995), offers a modification over the CIA. High PIA values (>84) would indicate

intense chemical weathering while lower values (~50) are characteristic of un-

weathered or fresh rock samples. Post- Archean Australian Shales (PAAS) has PIA

value of 79.

The red beds show very high PIA values ranging from 93-97 (average = 95.3 ±1.08

indicating that most of the plagioclase has been converted into clay minerals

(Mongelli et al., 2006). From Table.7.21, it is evident that the PIA for QPCm are

79.29 to 97.35 (average = 89.64) and for IOG quartzites it vary from 65.29 to 96.50

(average = 88.97), thus revealing high degree of plagioclase alteration and their

complete dissolution. In AK-C-N ternary diagram, all samples of QPC and quartzites

plot nearby AK corner between oligoclase (Og) and albite (Ab) (Fig.7.20). This

indicates that in most of samples, plagioclase has been near complete alteration in

them. This is the reason for low content of CaO and absence of plagioclase feldspar

in QPC and quartzites in the study area. Thus in the study area, CIA and PIA show

moderate degree of chemical alteration and high plagioclase index of alteration for

QPC and quartzites deposited along western margin of Bonai granite.

221

Th/U in Sedimentary Rocks:

Th/U in sedimentary rocks is of interest, as weathering and recycling result in

oxidation and removal of U with a resultant increase in this ratio. Weathering tends to

result in oxidation of insoluble U4+to soluble U6+with loss of solution and elevation of

Th/U ratios (McLennan et al. 1990; McLennan and Taylor 1980, 1991). Generally

high Th/U ratio in sediments reflect intense weathering condition, however this ratio

may change due to difference in oxidation state and hence, this ratio donot necessary

reflect source-area weathering conditions( Joo et al., 2005). Highly reduced

sedimentary environments can have enriched U leading to low Th/U ratios. The Th/U

ratio in most upper crustal rocks is typically range between 3.5 and 4.0 (McLennan et

al., 1993). In sedimentary rocks, Th/U values higher than 4.0 may indicate intense

weathering in source areas or sediment recycling. Upper crustal igneous rocks have

Th/U averaging about 3.8, with considerable scatter (Taylor and McLennan 1985;

Condie 1993; McLennan 2001).

In order to decipher source area weathering and also oxidation state during deposition

of QPC-quartzite sequence in the study are, a Th/U ratios were calculated for QPCm

and IOG quartzites. The calculated values indicate Th/U ratio for QPCm in the range

of 0.51-9.0 and 1.0-4.0 in quartzites. Most of samples of QPCm (two samples show

4.0 to 9.0) as well as quartzites show Th/U ratio of 4.0 in Th vs Th/U binary diagram

(Fig.7.22).

The low Th/U ratio is less than 4.0 are indicative of enrichment of uranium and

presence of reducing environment during the time of weathering and deposition of

sediment. The presence of detrital grains of uraninite and pyrite further support this

observation in the QPC. Low Th/U ratios <3.8 suggest a comparative enrichment of

uranium and also indicative of K-rich granites in provenance (Taylor and Mclennan,

1985).

222

7. 7. Tectonic Setting for QPC and IOG Quartzite: Major oxides, trace elements and REE have been utilized extensibly in the

interpretation of tectonic setting for sedimens and sedimentary rocks. Major

elemental composition has been used to discriminate different tectonic setting of

sedimentary basin (Bhatia, 1983). Roser and Korsch (1986) also used the major

oxides to infer tectonic settings. Certain trace element ratios including REE were also

used by various workers to decipher provenance study and tectonic setting of the

sedimentary rocks (Taylor and McLennan, 1985; Cullers et al., 1988; Cullers, 1994,

2000; McLennan 1989; McLennan and Taylor, 1991).

Armstrong-Altrin et al. (2004), Rashid (2005), Nagarajan et al. (2007), Rahman, and

Shigeyuki(2007), Hegde and Chavadi (2009) have used various geochemical

parameters to infer the source rock character and tectonic setting of clastic

sedimentary rocks. Osae et al. (2006) and Deru et al. (2007) have used petrography

and geochemistry to infer provenance and tectonic setting of Late Proterozoic Buem

Fig.7.22. Plots of (a) Th/U versus Th (after McLennan et al., 1993) for QPC matrix and IOG quartzites from western margin of Bonai granite, Orissa.

223

sandstones of southeastern Ghana and clastic sedimentary rocks from SE margin of

the Yangtze Block of South China respectively. Recently Mishra and Sen (2012)

have also utilized major and trace elements in deciphering the provenance, paleo-

weathering and tectonic setting of sedimentary rocks of Vindhyan Group from central

India.

The proposed major elemental geochemical parameters after Bhatia (1983), such as

Fe2O3 + MgO %, TiO2%, (Al2O3/SiO2), (K2O/Na2O) and Al2O3/(CaO + Na2O) have

been used to discriminate the plate tectonic setting of sedimentary basins. Roser and

Korsch (1988) used a discriminant function analysis of major elements (SiO2, Al2O3,

total Fe2O3, MgO, CaO, Na2O and K2O) in discriminating four different provenance

groups such as (1) mafic , (2) intermediate-dominantly andesitic detritus, (3) felsic

and plutonic and volcanic detritus and (4) recycled mature polycyclic quartzose

detritus.

In the present study, various geochemical parameters based on major oxides and

immobile trace elements have been used to infer the tectonic setting for QPC and

quartzite sequence deposited along western margin of Bonai granite in Orissa in

eastern India. In Fe2O3+ MgO vs TiO2 plot after Bhatia (1983), IOG quartzites show

concentration around passive margin setting while QPCm spread around passive

margin (PM) setting and also within active continental margin (ACM) tectonic

setting (Fig.7.23). Similarly when data is plotted on Fe2O3+ MgO vs Al2O3/SiO2

binary diagram after Bhatia (1983), both QPCm and quartzites occupy the position

nearby PM setting (Fig.7.24).

Immobile trace elements like La, Th, Sc and Zr are very useful in inferring the

tectonic setting of sediments. On La-Th- Sc ternary diagram of Bhatia and Crook

(1986), QPC and quartzites values but cluster near PM and ACM field (Fig.7.24). In

a similar way, on Th-Sc-Zr values on tectonic setting (after Bhatia and Crook 1986)

(Fig.7.25), QPC and quartzites diagram is away from Sc corner but they occupy the

position along Th-Zr line near PM and ACM. From this diagram, it is difficult to

infer tectonic setting. The data when plotted on SiO2-K2O+Na2O-TiO2+Fe2O3(t)+

MgO diagram (Kroonberg,1994), majority of the QPC and quartzite samples indicate

passive margin setting (Fig.7.27).

224

Fig.7.23 Fe2O3+ MgO vs TiO2 plot on tectonic setting discrimination diagram (fields are after Bhatia, 1983)

Fig.7.24. Fe2O3+ MgO vs Al2O3/SiO2 plot on tectonic setting discrimination diagram (fields are after Bhatia, 1983).

Fig.7.25. La-Th-Sc diagram for QPC matrix and IOG quartzites (after Bhatia and Crook 1986); OIA - oceanic island arc, CIA – continental island arc, PM and ACM– passive margin/ Active continental margin,

Fig.7.26. Th-Sc-Zr ternary plots on on tectonic setting discrimination diagram (after Bhatia and Crook 1986); OIA - oceanic island arc, CIA – continental island arc, PM and ACM– passive margin/ Active continental margin.

225

Roser and Korsch (1986) used major oxides like SiO2 and K2O/Na2O to decipher

the tectonic setting for sandstone-mudstone suite of rocks. Plotting of major oxide

data of QPC and quartzite on SiO2 vs K2O/Na2O, suggest passive margin setting for

both QPC and IOG quartzite.

Fig.7.28. QPCm and IOG quartzites plot on K2O/Na2O vs SiO2 after Roser and Korsch, 1986). Data for average Proterozoic sandstone (Closed green circle) are from Condie (1993). ARC- volcanic island arc; ACM,- active continental margin; PM- passive margin.

Fig.7.27. SiO2-K2O+Na2O-TiO2+ Fe2O3(t) + MgO of QPCm and IOG quartzites Kroonberg (1994).

226

First and second discriminant functions (DF1 vs. DF2) also favor a passive margin

Bhatia (1983) (Fig.7.28a). Thus collective geochemical data and their interpretation

including major element oxides and trace element data strongly suggest passive

margin setting for QPC-quartzite sequence from study area of Orissa.

Thus, in the present study, it may be suggested that QPC and quartzites have been

deposited in passive margin setting which is also substantiated by their high

SiO2/Al2O3 ratios, LREE enrichment, high Th/Sc, La/Sc and high Rb/Sr ratios (Osae

et al., 2006). According to Roser and Korsch (1986), passive margin sediments are

generally quartz-rich sediments derived from plate interiors or stable continental area

and deposited in intra-cratonic or on passive continental margins In Eu/Eu* vs.

(Gd/Yb) CN plot after McLennan and Taylor, 1991, all IOG quartzite and most of the

QPC samples show (Gd/Yb) CN ratio >2.0 and Eu/Eu* ratio of < 0.85 whereas few

QPC samples show <2.0 values of (Gd/Yb) CN and Eu/Eu* ratio less than 0.85, thus

indicating that both QPC and quartzites have been derived from Archean rock

derivative source/components ( Fig.7.29).

Fig.7.28a. QPCm and IOG quartzites from western margin of Bonai granite, Orissa (Field after Bhatia, 1983). DF-1 = (-0.0447 x SiO2 %) + (-0.972 x TiO2 %) + (0.008 x Al2O3 %) + (-0.267 x Fe2O3 %) + (0.208 x FeO %) + (-3082 x MnO %) + (0.104 x MgO %) + (0.195 x CaO %) + (0.719 X Na2O % ) + (-0.032 x K2O % ) + (7.510 x P2O5 %). DF-2 = (-0.421 x SiO2 %) + (1.998 x TiO2 %) + (-0.526 X Al2O3 %) + (-0.551 X Fe2O3 %) + (-1.610 x FeO %) + (2.720 X MnO % ) + ( 0.881x MgO % ) + (- 0.907 x CaO % ) + (-0.117 Na2O % ) + ( -1.840 x K2O %) + ( 7.244 x P2O5 %).

227

7.8: Mineral Chemistry: Mineral chemistry is carried out in order to have detail chemical analysis of

individual mineral grains to get comprehensive idea of its chemistry which in turn is

helpful in deducing the genesis of those mineral grains in the rocks. It is done with

the help of Electron Probe Micro-Analyser (EPMA). For the purpose, grains of

uraninite, pyrite, monazite, zircon and galena present in QPCm was subjected for

mineral analysis.

Chemical analysis of uraninite, pyrite, monazite, zircon and galena in QPC have

been carried out on polished thin sections using Cameca SX-50 Electron Microprobe

(EMP) at Atomic Minerals Directorate for Exploration and research(AMD),

Hyderabad by Wavelength Dispersive Spectrometry (Nayak et al., 2008). The EMP

analyses were performed at an accelerating voltage of 15 keV and 40 nA beam

current over a beam diameter of 1 µ for optimum count statistics on a number of

major and minor elements. Quantitative data were reduced using PAP procedure of

Pouchou and Pichoir (1991).

Fig.7.29. Plots of Eu/Eu* vs. (Gd/Yb) CN for QPC matrix and IOG quartzite , western margin Bonai Granite, Orissa. Field after McLennan and Taylor, 1991. UCC : Taylor & McLennan, 1985; Granite – Jayananda, 1995; Granite-Jayaram et al, 1983; Mafic rocks- Khan & Rao et al, 1992, 1999; Shale- Rao et al ,1999( in Nagarajan et al., 2007).

228

The concentration of the elements was determined using both natural and synthetic

standards. The relative error is <1% in case of major and minor elements and 4-10 %

in case of trace elements and the detection limit is 100 ppm. The elements, standard

used , x-ray line and crystals used in analysis are as follow: U- uraninite- M-PET;

Th- ThO2- M-PET; Pb- Pbs- M- PET; Al- Al2O3- K- TAP; Si- Andradite- K-

TAP; P- Apatite- K-TAP; Ca- Andradite- K- PET; Ti- MnTiO3- K-PET; Fe-

Fe2O3- K-LIF;Y- Y- K- TAP; Mg- MgO- K-TAP; La- LaB6- L- PET; Ce-

CeAl2- L-PET; Pr- PrF3- L-LIF; Nd- NdF3- L- LIF; Sm- SmF3- L- LIF; Gd-

GdF3- L- LIF; Tb- TbF3- L- LIF; Dy- DyF3- L-LIF; Ho- HoF3- L-LIF; Er- ErF3-

L-LIF; Tm- TmIGNOT- L-LIF; Yb- YbF3- L-LIF; Lu- LuSi2- L-LIF; S- FeS2-

K-PET; Fe- Fe2O3- K-LIF; Ni- NiO- K-LIF; Co- Co- K-LIF; Cu- Cu- K-LIF;

As- AsGa- L-TAP; Ag- Ag- L-PET; Cd- Cd- L-PET; Sb- Sb2S3- L-PET; Zr-

Zr- L- TAP; Hf- HfO2- L- LIF.

The mineral chemistry important ore and heavy minerals in QPC are discussed

below.

Uraninite: The EMP analysis of uraninite is given in Table.7.18. The UO2

content in grain-1 of uraninite (three point analysis) varies from 66.04 to 71.73 wt

% whereas ThO2 and RE2O3 shows variation from 5.49 to 6.42 wt % and 1.57 to

1.76 wt % respectively. The PbO content ranges from 10.57 to 12.59, SiO2 from

2.22 to 7.02, TiO2 from 1.14 to 5.00, Y2O3 from1.10 to 1.32 and CaO content ranges

from 0.31 to 0.52 wt %. Single point analysis of grain-2 of uraninite indicate 63.86

wt % UO2, 5.48 wt % ThO2, 11.12 wt % PbO, 8.05 wt % SiO2, 0.14 wt % TiO2,

3.06 wt % Y2O3, 0.63 wt % CaO and 2.23 wt % RE2O3(Table.7.18). From

Table.7.18, it appears that grain-2 of uraninite has low content of U, higher

concentration of SiO2, TiO2 and Y2O3 and RE2O3 when compared to grain-1. High

SiO2 may be due to post- depositional hydrothermal alteration (Kumar et al., 2012).

The composition of the uraninite grain has a major bearing on the genesis

(Grandstaff, 1975). In general, low temperature, hydrothermal uraninites contains

little amount of thorium, if present, while uraninite derived from pyrogenetic sources

like granites and pegmatites contain appreciable thorium content (Frondel, 1958;

Grandstaff, 1975). According to Augustithis (2000), the pegmatitic uraninite

generally shows presence of Th, Y and RE2O3 and Ti as an important constituent

229

whereas hydrothermal uraninite shows absence or very low contents of Th, Y, Nb,

Ta and rare-earths.

Fritsche and Dahlkamp (2001) also found in their study that uranium oxides of

pegmatite always contain significant ThO2 ranging from 1.5 to 10 %. Genetic aspects

of uraninites have also been studied from different host rock and environments of

India based on their mineral chemistry (Sengupta et al. 2005; Roy and Roy, 2008).

Roy and Roy (2008) has shown in their study that the composition of uraninites are

controlled by temperature of formation which can be classified as high and low-

temperature types, the high temperature uraninites are marked by higher

concentration of ThO2, RE2O3 and Y2O3 and lower content of SiO2, CaO and TiO2

whereas low temperature uraninites have relatively lower concentration of ThO2,

RE2O3 and Y2O3 and substantial amount of SiO2, CaO and TiO2.

Dhanaraju (2009) is also of the opinion that chemical composition of the primary,

discrete U-phases varies with their genetic environments and relative age of

formation. Th and Pb contents of the U-phases like uraninite and pitchblende are

important indicators of their temperature and ages of formation respectively. In view

of such importance, U- Th- Pb- REE geochemistries on rare discrete uraninite

minerals in QPC have been carried out. Preliminary electron microprobe study

analyzed high Th (5.48-6.42 %) and high REE (1.57 to 2.23wt %) content in

uraninites from QPC in the present study area indicating their high temperature

origin and probably derivation from granitic and pegmatitic source represented by

Bonai granite/Singhbhum granite with numerous pegmatitic injections in the area. In

order to confirm the source of uraninite in QPC, analysis of discrete uraninite grain

from QPC was compared with the analysis of uraninites from various genetic

environments and areas. It is evident that the uraninite composition of QPC matrix is

akin to that of pegmatitic uraninite reported from various locations (Table.7.25).

It is also important to mention here that when analysis of uraninite of QPC in the

present research area is compared with well established hydrothermal uraninites of

Singhbhum shear zone, it shows very high ThO2 content but very low UO2/ThO2

ratio (Table.7.19), thus negating their hydrothermal origin. Comparatively higher

content of Th in case of Turamdih (upto 2.23 wt %) and Jublatola (upto 3.35 wt %)

230

hydrothermal uraninites from Singhbhum shear zone in Singhbhum-Orissa Craton

has been explained due to crystallization of uraninite at a relatively higher

temperature as compared to Jaduguda, NarwaPahar in the same shear zone (Varma et

al., 1988).

According to Fritsche and Dahlkamp (2001), UO2/ThO2 and CaO/ThO2 ratio of

uranium oxides are helpful in deciphering their formational environments. It has been

shown that UO2/ThO2 and CaO/ThO2 ratio in pegmatitic uraninite is lowest which

varies from 11-60 and <0.10-0.20 respectively as compared to uraninites of other

environments (Table.7.19). When the values of these ratios in uraninites from study

area are compared, it resembles with those of pegmatitic uraninites, thus further

confirming the derivation of uraninite grain in QPC from pegmatite.

In addition to this, the analysis of uraninite from QPC were also compared with the

data on uraninites in QPC from Witwatersrand, South Africa, Blind River, Canada,

Dharwar Craton, South India and Daitari basin of Singhbhum- Orissa Craton, eastern

India (Table.7.20). The UO2-ThO2 binary plot (Fig.7.30) shows that the uraninites

from Bagiyabahal, Orissa occupy the field of Witwatersrand uraninite. The plot

indicate that the UO2 content in QPC uraninite in the study area is higher than the

uraninites of Blind River QPC, Canada and Walkunji in Dharwar Craton of South

India, Karnataka, India. On the other hand, the ThO2 concentration is similar to

Canadian uraninites but much lower than that of Walkunji. Although the U and Th

values for QPC uraninites from study area donot show much variation as in the case

of Witwatersrand uraninites , but are restricted similar to Canadian and Walkunji

uraninites (Dharwar Craton), thereby reflecting their derivation from a single

provenance. However to constrain this aspect conclusively, much more data are

needed and evaluated from QPC uraninites.

The U, Pb, Th and individual REE are given in Table.7.21 and composition based on

16O are in Table.7.22. The chondrite normalized and without normalized vaues of

REE is also given in Table.7.23. Elliot Lake QPC uraninite, Canada (Roscoe, 1969 in

Fryer and Taylor, 1987) and Rossing Granite-pegmatite, Namibia (Berinag et al.,

1976 in Fryer and Taylor, 1987) have U/Th in the range of 9.1 and 9.0 respectively.

Total REE in high temperature uraninite mainly from granite pegmatite and alaskitic

231

granite show elevated concentration > 15000 ppm while uraninite from the

hydrothermal vein and unconformity type uranium deposits have <7500 ppm ( Fryer

and Taylor,1987). Uraninite from the study area show U/Th ratios variation from

10.17 to 12.10 (Table. 7.23) and their total Σ REE ranges from 13604.6 ppm to

19431.3 ppm which is nearer to the values reported from high temperature granitic

rocks(7.23). Thus high U/Th and high content of total REE in uraninite grain

indicative of its high temperature origin and derivation from granitic/pegmatitic

provenance. Chondrite normalized REE plot for uraninite indicate depletion of LREE

and comparatively enrichment of HREE. This pattern is is also comparable with REE

pattern of uraninites from granitic pegmatites (Fryer and Taylor, 1987) (Fig.7.32).

However, more data is required to be collected to arrive at definite conclusion.

Pyrite: Pyrite occurs in variable shapes and sizes. They are sub-rounded to irregular

shaped within the matrix of QPC (Chapter-6). The size of sub-rounded pyrite shows

variation from 0.05 to 0.25 mm. The analysis of pyrite grains are given in Table.7.24.

Six pyrite grains have been analyzed with three point analyses in each grain except in

grain-3 where only one point analysis has been done. The Fe content in pyrite ranges

from 46.64 to 47.85 wt % and their S are in the range of 53.23 to 54.47 wt %. Ni

content varies from 0.00 to 0.09 and Co is from 0.00 to 0.16 wt %. The Cu content

shows variation from 0.00 to 0.07 wt % whereas the concentration of As ranges

from 0.02 to 0.19 wt %. The high As content (0.02-0.19 wt %, mean = 0.085)

revealed arsenian nature of pyrite.

Trace element contents in pyrite, particularly their Co and Ni contents and Co/Ni

ratio has been used extensively by various workers to decipher the origin of pyrites

(Loftus-Hills and Solomon, 1967; Price, 1972; Bralia et al. 1979; Campbell and

Ethier, 1984; Clark et al. 2004; Pal et al. 2007). According to Loftus-Hills and

Solomon (1967) and Price (1972), Co/Ni ratios of syngenetic sedimentary and

diagenetic pyrites are highly variable but are typically <1.0; Co and Ni in these

pyrites most commonly are less than 100 ppm ranging up to a few hundred parts per

million. Magmatically segregated sulfides are also generally characterized by Co/Ni

ratios of <1.0 but with much higher concentrations of these elements in the range of

1,000s of parts per million (Campbell and Ethier, 1984; Pal et al. 2007). High trace

element contents and high Co/Ni ratios are common in pyrite precipitated from

232

hydrothermal fluids, volcanogenic massive sulfides deposits (Loftus-Hills and

Solomon 1967; Price 1972; Bralia et al. 1979; Pal et al., 2007) and IOCG deposits

(Pal et al. 2007).Very high Co/Ni (5-50) average values in pyrites are characteristics

of volcanogenic origin of the deposits itself (Price, 1972).

Cobalt is typically the more abundant component in ores of high-temperature origin,

but in sedimentary pyrite Ni levels may exceed those of Co (Abraitis et al.

2004). Houston et al. (1995) conclude that high Co contents in pyrite are

characteristic of high-temperature feeder zones in volcanic-hosted massive sulfide

deposits. In order to get the preliminary knowledge on the genetic aspects of the

pyrites in QPC from western margin of Bonai granite, six grains (16 point analysis)

of pyrite from QPC were analyzed by EPMA. The analysis of different trace elements

is given in Table.7.24 whereas the analysis of Co and Ni and Co/Ni ratios in pyrites is

tabulated in Table.7.25. In the light of the above data, low concentration of both Co

(upto 0.16 wt %, mean = 0.042) and Ni (upto 0.09 wt %, mean = 0.045) and low

ratio of Co/Ni (0.24-1.46) with a mean of 0.63 in pyrite grains are suggestive of

their sedimentary and diagenetic origin and not of hydrothermal origin. The

sedimentary origin of pyrite in QPC is also revealed in binary plot of Co vs Ni after

Campbell and Ethier, 1984(Fig.7.31).

Arsenic has a restricted solubility in pyrite but is commonly present as a minor

element at ppm to low wt. % levels. According to Abraitis et al. 2004, arsenic levels

in pyrite vary extensively between 6 and 96,000 ppm (9.6 wt. %). As-bearing pyrites

are generally gold bearing (Clark et al. 2004; Wenchao et al. 2008). Large amounts

of “invisible gold” are often present in the As-bearing minerals (Abraitis et al. 2004;

Saha and Venkatesh, 2002). According to Zacharias et al. 2004, many As-rich pyrites

show enrichment in gold in addition to enrichment in arsenic. The natural pyrites in

the Deep Star Carlin deposit contain up to 0.37 wt. % Au (Fleet and Mumin, 1997).

On the other hand, Tauson, 1999 suggested very low solubility of gold in As-free

pyrites (~ 2+1ppm Au at 500ºC temp. and 1 Kbar).

Oberthiir et al. (1997) reported concentrations of selected Platinum Group Elements

(PGE) in pyrite grains in ore samples from the Great Dyke, Zimbabwe. Pyrite was

found to be a significant host for Pt, with pyrites having average contents of 233 ppm

233

(based on 14 pyrite analyses). The concentrations of the other elements were lower,

with average Pd, Ru and Rh contents of 9, 40 and 10 ppm, respectively. They not

only noted small metallic inclusions of PGE within the ore samples, but also suggest

that variable amounts of these metals also exist in solid solution within the sulfide

phases, including pyrite. In view of the above observations, pyrite in QPC, although

contain moderate arsenic (0.02 to 0.19 wt %), can be analyzed for their gold as

well as PGE, particularly Pt content as there are some encouraging results.

Table 7.18: EPMA data indicating the composition of uraninite grains in QPC, Western margin of Bonai Granite Pluton, Orissa.

B- Border, C- centre

Oxides (wt %) Grain 1 Grain 2 B C B

UO2 66.04 71.13 67.98 63.86 ThO2 6.41 6.42 5.49 5.48 PbO 10.57 12.59 11.19 11.12

Al2O3 0.44 0.10 0.61 1.95 SiO2 3.15 2.22 7.02 8.05 P2O5 0.37 0.17 0.37 0.49 CaO 0.52 0.31 0.49 0.63 TiO2 5.00 1.14 3.08 0.14 MnO 0.06 0.02 0.04 0.10 FeO 0.27 0.13 0.35 0.16 Y2O3 1.10 1.32 1.16 3.06

RE2O3 1.75 1.57 1.76 2.23 Total 95.68 97.12 99.54 97.27

234

Fig. 7.30. UO2-ThO2 plot for uraninite from study area with fields of uraninite from Witwatersrand, South Africa, Blind River QPC, Canada( after Grandstaff,1981) and Walkunji from Dharwar Craton, South India(after Varma et al.,1988).

235

Table.7.19. Electron microprobe analysis of uraninites from various environments along with uraninites from QPC of Bagiyabahal, western margin of Bonai granite pluton, Orissa

Environment/Areas UO2 ThO2 PbO CaO UO2/ThO2 CaO/ThO2

Pegmatitic uraninite (after Fristche

and Dahlkamp, 2001) (n =50) 72.38-4.29 (83.77)

1.57- 6.40 3.32- 10.77 0.04- 1.16 (< 1.5 wt %)

11- 60 <0.10– 0.20

Metamorphite (Fristche and Dahlkamp, 2001) (n = 107)

90.59-98.2 (94.39)

0.10-1.11 (0.48)

0.54-2.91 (1.66)

0.54-0.60 ( 0.41)

85-906 (197)

0.1-6.0 (0.85)

Metasomatite (Fristche and Dahlkamp, 2001) (n = 41)

63.91-74.4 (69.17)

0.13-0.15 (0.14)

2.78-19.94 (6.86)

2.11-2.32 (2.94)

426-572 (499)

18-24 (21)

Singhbhum shear Zone hydrothermal uraninite (n=

18)), after Verma et.al., 1988

52.48 - 63.08

0.086 - 3.35

1.97 - 9.92

-

24.4 – 454.5

-

Bagiyabahal QPC, western margin of Bonai granite, Orissa

Present study(N=4).

63.86- 71.13 (67.25)

5.48-6.42 (5.95)

10.57- 12.59 (11.37)

0.31-0.63 (0.49) 10.30-12.38 (11.35)

0.05-0.11(0.08)

236

Table. 7.20. Comparison of Electron microprobe analysis of uraninite from Bagiyabahal with QPC of Canada, South Africa and QPC of Orissa and Dharwar craton, India( average values are shown in bracket).

Oxides

(wt %)

Study area (Koira

Basin),Western margin of

Bonai granite, Orissa, N=4

Blind River QPC,

Canada

(Grandstaff,1975)

Witerwatersrand QPC, South

Africa (Feather,1981), (N=33)

Daitari Basin QPC,

Orissa (Kumar et al.,

2009), N=16.

Walkunji QPC, Dharwar

craton, Karnataka, India

(after Varma et al., 1988)

UO2 63.86- 71.13 (67.25) 58.0- 69.0(60.0) 61.1-72.5( 67.20) 69.91 – 83.90 (75.81) 45.32-54.70 (48.70)

ThO2 5.48-6.42 (5.95) 4.0- 9.0(6.50) 1.4-10.2 (3.90) 3.06 – 10.26 (6.33) 8.24-10.74 (9.85)

Pb O 10.57- 12.59 (11.37) 18.00 14.7-30.3 (23.60) 8.45 - 10.29 (9.37) 6.54-18.76 (10.93)

ΣRE203 1.57- 2.23 (1.83) 3.0-8.0 - 1.69 - 1.94 (1.82) -

Y2O3 1.10- 3.06 (1.66) 2.5 - 1.47- 1.66 (1.56) -

UO2/ ThO2 10.30-12.38 (11.34)

8.0- 12.0 (10.00)

6.4-47.4 (17.20)

7.42 - 21.17(11.98)

4.67-5.43(5.05)

237

Table 7.21: U, Th, Pb and REE oxides in uraninite grains

Table 7. 22: U, Th, Pb and REE oxides in uraninite grains (Based on 16 O)

Th 0.52 0.526 0.450 0.449 U 5.29 5.695 5.443 5.113 Y 0.21 0.253 0.222 0.586 La 0.0 0.009 0.017 0.008 Ce 0.0 0.012 0.0 0.001 Nd 0.01 0.044 0.027 0.0 Sm 0.03 0.0 0.01 0.009 Gd 0.05 0.019 0.037 0.062 Tb 0.05 0.035 0.0 0.022 Dy 0.02 0.039 0.034 0.034 Er 0.0 0.0 0.0 0.010 Yb 0.0 0.021 0.038 0.054 Lu 0.01 0.009 0.003 0.007 Pb 1.02 1.220 1.084 1.077

Total 7.22 7.88 7.36 7.43 Total REE 0.38 0.44 0.39 0.79

U/Th 10.17 10.82 12.10 11.39

Element/oxide Grain-1A Grain1B Grain1C Grain2

ThO2 6.41 6.42 5.49 5.48 UO2 66.04 71.13 67.98 63.86 Y2O3 1.1 1.32 1.16 3.06 La2O3 0 0.07 0.13 0.06 Ce2O3 0 0.09 0 0.01 Nd2O3 0.08 0.34 0.21 0 Sm2O3 0.26 0 0.08 0.07 Gd2O3 0.43 0.16 0.31 0.52 Tb2O3 0.44 0.3 0 0.19 Dy2O3 0.15 0.34 0.29 0.29 Er2O3 0.02 0 0 0.09 Yb2O3 0 0.19 0.35 0.49 Lu2O3 0.05 0.08 0.03 0.06 PbO 10.57 12.59 11.19 11.12 Total 85.55 93.03 87.22 85.30

238

Table 7.23: Chondrite normalized and without normalized values of REE in uraninite grains

Uraninite

Element Grain 1 A Grain 1B

Grain 1C Grain 2

Chondrite normalized La 0.000 0.251 0.466 0.215 Ce 0.000 0.125 0.000 0.014 Nd 0.151 0.640 0.395 0.000 Sm 1.511 0.000 0.465 0.407 Eu Gd 1.873 0.697 1.351 2.266 Tb 10.580 7.213 0.000 4.568 Dy 0.530 1.202 1.026 1.026 Ho 0.799 0.000 5.749 0.000 Er 0.109 0.000 0.000 0.492 Tm 9.565 0.000 0.000 15.941 Yb 0.000 1.036 1.909 2.672 Lu 1.787 2.859 1.072 2.144

Total REE (without chondrite normalized Uraninite)

La 0 0.0595 0.1105 0.051 Ce 0 0.0765 0 0.0085 Nd 0.0688 0.2924 0.1806 0 Sm 0.2236 0 0.0688 0.0602 Gd 0.37281 0.13872 0.26877 0.45084 Tb 0.38192 0.2604 0 0.16492 Dy 0.1305 0.2958 0.2523 0.2523 Ho 0.0436 0 0.31392 0 Er 0.01748 0 0 0.07866 Tm 0.23625 0 0 0.39375 Yb 0 0.16682 0.3073 0.43022 Lu 0.04395 0.07032 0.02637 0.05274 Σ REE in % 1.51891 1.36046 1.52856 1.94313 Σ REE in ppm 15189.1 13604.6 15285.6 19431.3

239

Table 7.24: EPMA data on pyrite grains associated with QPC (in wt %)

Oxide (Wt %) Grain1 Grain2 Grain3 Grain4 Grain5 Grain 6

Fe 47.23-47.73 47.52-47.69 47.85 47.34-47.50 46.81-47.45 46.64-46.95 S 53.23-53.82 53.29-53.73 53.66 53.78-54.47 53.80-54.10 54.20-54.44 Ni 0.05-0.08 0.02-0.08 0.02 0.00-0.08 LDL-0.06 0.05-0.09 Co LDL-0.05 LDL-0.06 LDL LDL-0.04 LDL-0.02 0.07-0.16 Cu LDL-0.02 LDL 0.05 LDL 0.03-0.04 LDL-0.07 Zn LDL-0.05 0.02-0.20 0.03 LDL-0.08 LDL-0.17 LDL-0.05 As 0.09-0.13 0.03-0.07 0.08 0.06-0.09 0.02-0.14 0.06-0.19 Ag LDL-0.10 LDL 0.09 LDL-0.01 LDL-0.04 LDL-0.03 Cd LDL-0.05 LDL-0.05 LDL LDL-0.09 0.01-0.04 LDL-0.01 Sb LDL LDL-0.04 LDL LDL-0.01 LDL-0.06 LDL-0.03

Total 101.20-101.38 101.18-101.55 101.78 101.34-102.09 101.31-101.69 101.10-101.96

LDL: Lower than detection limit

240

Table 7.25. Concentration of Co and Ni content and their ratio in pyrite grains in QPC, western margin of Bonai granite, Orissa Sundargrh district, Orissa (average of 3 point analysis, in wt %).

S. No. Co Ni Co/Ni

Grain1 0.017 0.07 0.24

Grain2 0.02 0.04 0.50

Grain3 LDL 0.02 -

Grain4 0.02 0.043 0.46

Grain5 0.013 0.027 0.48

Grain6 0.107 0.073 1.46

Average 0.029 0.045 0.63 (n=5)

Fig. 7.31. Co and Ni plot form pyrites from QPC of study area. Field A for pyrite and pyrrhotite of volcanic origin; field B- pyrite and pyrrhotite of sedimentary affinity and C- field of magmatic segregation for pyrite and pyrrhotite (field after Campbell and Ethier, 1984).

241

Monazite: Monazite [(La, Ce, Th) PO4] is a common accessory mineral in felsic

igneous rocks and medium- and high-grade metasedimentary rocks (Overstreet, 1967;

Chang et al., 1996; Spear and Pyle, 2002 in Rasmussen and Muhling, 2009). Detrital

monazite is a common constituent of siliciclastic sediments and sedimentary rocks,

where it is typically concentrated in heavy mineral bands, in some cases forming

economic placer deposits. It is generally stable during sedimentation and diagenesis

(Morton and Hallsworth, 1999). The Witwatersrand Supergroup, monazite has only

been reported in a few cases, and is regarded as very rare (Feather and Koen, 1975;

Feather, 1981; Oberthür, 1987; Fleet, 1998). Where present, it generally occurs in

heavy mineral bands as rounded grains and is interpreted to be detrital in origin

(Liebenberg, 1955).

Monazite is an important detrital radioactive grain present in matrix of QPC in the

study area. Mineral chemical analysis by EMP has indicated 0.01 to 0.27 wt % UO2

(average = 0.17 wt %), 0.12 to 1.19 wt % ThO2( average = 0.62 wt %), PbO is less

than detection level(LDL), 1.11 to 7.05 wt % SiO2 ( average = 3.24 wt %) and 0.88 to

1.49 wt % CaO( average = 1.18 wt %). The content of P2O5, Y2O3 and RE2O3 ranges

from 25.30 to 26.11 wt % (average = 25.63 wt %), 1.10 to 1.67 wt % (average = 1.38

wt %) and 58.62 to 61.00 wt % ( average = 59.62 wt %) respectively ( Table. 7.26).

Thus, mineral data indicate that monazite grains are rich in rare earth oxides, Y and

phosphates. The monazite REE patterns are characterized by LREE enrichment

similar to those seen in monazite from igneous and metamorphic rocks (Bomins and

Crocket, 2011). The chondrite normalized pattern for three detrital monazite grains

are shown in Fig.7.33, It indicates very steep LREE fractionated pattern with LREE

enrichment and strong negative Eu anomaly. Negative Dy and Yb anomaly is also

noted. Sample -3 show steep depleted trends in HREE but other two grains-1 & 2

shows sharp increase from Gd to Dy and then increase from Dy to Tm and then sharp

decrease from Tm to Yb or Lu. U, Th, P, Y data suggest their derivation from granitic

rocks.

242

Table 7.26: Electron Probe Micro analysis of monazite grains from QPC, Western margin of Bonai granite, Orissa.

Oxide (wt % ) Grain-1 Grain-2 Grain-3 Average

UO2 0.01 0.22 0.27 0.17

ThO2 0.12 0.56 1.19 0.62

PbO LDL LDL LDL LDL

SiO2 1.56 7.05 1.11 3.24

P2O5 26.11 25.30 25.47 25.63

CaO 1.49 0.88 1.17 1.18

TiO2 LDL 0.04 0.03 -

FeO 0.20 LDL LDL -

Y2O3 1.10 1.67 1.37 1.38

RE2O3 59.85 58.62 61.00 59.62

Total 89.85 94.34 91.61 91.93

Fig. 7.32.Chondrite normalized REE plot of uraninite grain in QPC matrix, western margin of Bonai granite, Orissa.(CN values after Sun and McDonough,1995).

243

Zircon: Zircon is a chemically inert and a refractory mineral which can withstand

weathering and transport processes as well as high temperature metamorphism and

anatexix (Hinton and Upton, 1991). Zircon chemistry is simple and usually contains

ZrO2, HfO2 and SiO2 about more than 99 % of the total oxides with other elements

commonly present as substitutes are Y, REEs, Th and U (Romans et al., 1975). The

EPM analysis of three detrital zircons from QPC matrix of study are is given in

Table. 7.27. Since zircon is highly resistant minerals, it is commonly found in almost

all siliciclastic rock as detrital grains.

It is also observed that zircon always contains a some amount of hafnium, the

HfO2/ZrO2 ratio varies but is normally about 0.01.The highest ratio is found in

metamict zircon(0.06) while it increases from 0.015 for zircons in nepheline- syenites

to 0.04 for granites(Rankama and Sahama,1950). According to Deer et al. (1966),

HfO2/ZrO2 ratio in zircon is about 0.01 but rises to 0.04 in granite. In the present

study area, zircon from QPC matrix has indicated 0.015 to 0.024 which is similar to

zircon from granites (Kevin and Kyser, 1993), thus suggest derivation of zircon in

QPC from granitic rocks.

Fig.7.33. Chondrite normalized REE plot of monazite detrital grain in QPC matrix, western margin of Bonai granite, Orissa. (CN values after McDonough and Sun, 1995).

244

Table 7.27: Electron Probe Micro analysis of Detrital zircon grains from QPC, Western margin of Bonai granite, Orissa.

Th/U ratio is also a good indicator for differentiate among different provenance of

zircon. According to Ahrens et al. (1967), Th/U ratio in zircon is generally less than

1.0 than the average Th/U ratio of 4.0 for crustal rocks indicating a preferential

incorporation of U versus Th in zircon during crystallization from magma. The range

and average of Th/U ratio in zircon from granitic zircon suites range from 0.15 to

1.20 and 0.47. Igneous zircon generally contains less that 1 wt % of the REE and Y.

In the present study, Th/U ratio varies from 0.28 to 1.61, thus revealing granitic

source of zircon (Kumar et al., 2012).

Oxides

(Wt %)

Grain-1 Grain-2 Grain-3

B C B C C UO2 2.05 0.56 0.39 0.34 0.08 ThO2 3.30 0.16 1.42 0.31 LDL PbO 0.01 0.16 LDL LDL 0.03

Al2O3 1.33 0.19 0.51 0.42 0.04 SiO2 24.56 28.80 27.29 30.04 34.93 MgO LDL 0.03 0.03 0.01 0.06 CaO 0.23 0.13 0.11 0.06 0.07 TiO2 0.32 0.04 0.04 0.10 0.00 MnO 0.01 0.01 LDL 0.01 0.01 FeO 0.39 0.68 0.23 0.01 0.12 Y2O3 0.49 0.13 LDL LDL 0.57 ZrO2 54.08 60.20 60.83 62.31 58.84 HfO2 0.80 1.46 1.35 1.00 0.96

RE2O3 1.28 0.56 0.47 0.49 0.36 Total 88.85 93.11 92.67 95.10 96.07

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Galena: The data on galena chemical composition is given in Table. 7.28. The data

indicate that galena has 72.44 % Pb and 11.24 % S and 0.21 % Ag. Since at present

data for only one galena is available, it is too early to make any conclusion out of

this. However, its presence as inclusion within uraninite grain suggests radiogenic

origin. Similar type of galena has also been noted in detrital uraninite grains in QPC

from Daitari IOG basin of Orissa (Kumar et al., 2011).

Table 7.28: Electron Probe Micro analysis of Galena grain from QPC, Western margin of Bonai granite, Orissa

Fe, Ni, Co, Zn, As, and Mo are = 0.00 wt % LDL- Less than detection level, C-Core.

Oxide (Wt %) Galena (Grain-1) C

S 11.24 Cu 0.06 Ag 0.21 Cd 0.03 Sb 0.05 Pb 72.44