Petrological and Geochemical Studies on Granitoids in BibinagarBhongir Area, Nalgonda District, Telangana, India.

Petrological and Geochemical Studies on Granitoids in BibinagarBhongir Area, Nalgonda District, Telangana, India.

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  Ch.Ramakrishna1 .et al. Int.Journal of Engineering Research and Applications www.ijera.com ISSN: 2248-9622, Vol. 6, Issue 4, (Part - 2) April 2016, pp.57-63 www.ijera.com 57|P a g e Petrological and Geochemical Studies on Granitoids in Bibinagar- Bhongir Area, Nalgonda District, Telangana, India. Ch. Ramakrishna1 , G. Mallesh2 , Ch. Ravi3 , and M. Narsimha Reddy4 1234 Department of Geology, University College of Science, Osmania University, Hyderabad-07 ABSTRACT The Granitoids of the Bibinagar- Bhongir area in the Nalgonda district are purely high potassic calc alkaline and meta aluminous and A-type belongs to Peninsular Gneissic Complex of the Eastern Dharwar Craton. The petrographic study of granitoids indicates that of pure magmatic origin in the form of different magmatic textures viz. perthitic, porphyritic and poiklitic textures. Geochemically the granitoids are rich in K2O & Na2O suggesting source from calc-alkaline magma. The Granitoids are falling mostly in the volcanic arc field on Yb vs Ta discrimination plot. The REE pattern shows strong Eu negative anomaly, suggesting early separation of plagioclase and the enhanced level of LILE relative to HFSE in Bibinagar-Bhongir granitoids points to the subduction zone enrichment and/or crustal contamination of the source region. Key words: Granitoids, Geochemistry, Petrology, I. INTRODUCTION The Indian Peninsula is traditionally considered to be a monolithic continental shield constituted by crystalline rocks. Later, the Precambrian rocks of India were divided into distinct segments based on principal orogenic trend, viz. Dharwar, Eastern Ghat, Aravalli and Satpura. Several genetic classifications have been attempted reflecting divergent interpretation of the tectono-stratigraphic make-up of different parts of the peninsular shield – [A Manual of the Geology of India, Vol. 1, Pt. 1, Spl. Pub. No. 77, Geol. Surv. Ind., (2006)]. The basement and crust i.e. granites of the middle to late Archaean age are tonalite- trondhjemite-granodiorite (TTG) suites Swami Nath and Ramakrishnan (1981); Naqvi et al. (1983); Rama Rao and Divakara Rao (1994). The Closepet granite of the Indian sub-continent rich in potassic has been formed during the Archean to Paleoproterozoic Radhakrishna (1956); Friend (1984); Divakara Rao et al. (1999); Jayananda and Mahabaleswar (1992); Jayananda et al (1995). The middle to late Proterozoic granitic events are of local significance. The younger granite are meta- aluminous, alkali rich-calc-alkaline series, A- type and volcanic arc granites, syn-collision to late orogenic. Geochemically the tectonic setting of granite can be inferred clearly through geochemistry. In this paper we describe the geology and geochemistry of a granitic rock of Peninsular Gneissic Complex. The area under study forms a part of the Eastern Dharwar craton located within the state of Telangana. They area bounded by Latitudes 17.30 to 17.80 N; 78.60 to 79.00 E adjoining the Bibinagar-Bhongir of Nalgonda district [Fig 1(a, b)]. Fig-1a: Geology map of Telangana Fig-1b: Geology map of Nalgonda, square showing study area. II. GEOLOGICAL SETTING Geology of the Dharwar craton has been synthesized and summarize by many pioneers viz., Swaminath and Radhakrishnan (1981); Naqvi (1981); RESEARCH ARTICLE OPEN ACCESS
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  Ch.Ramakrishna1 .et al. Int.Journal of Engineering Research and Applications www.ijera.com ISSN: 2248-9622, Vol. 6, Issue 4, (Part - 2) April 2016, pp.57-63 www.ijera.com 58|P a g e Radhakrishna (1983); Radhakrishna and Naqvi (1986); Naqvi and Rogers (1983,1987); Rogers (1996) Naqvi (2005) that the Dharwar Province is essentially a granite-greenstone terrain characterized by a number of NNW-SSE trending belts of schistose rocks separated by granitic terrains. The Province is divisible into western and eastern parts along a major shear zone west of the Closepet Granite [A Manual of the Geology of India, Vol. 1, Pt. 1, Spl. Pub. No. 77, Geol. Surv. Ind.,(2006)]. The Eastern Dharwar Craton (EDC) based on the lithological assemblage and its environment of emplacement or geodynamic setting is described an intra-oceanic [Manikyamba et al. (2004, 2005); Naqvi et al., (2006)]. The EDC comprised different type of granites. The state of Telangana geologically is located in the southeastern corner of the Precambrian shield. III. PETROGRAPHY The Granitoid rocks of the Peninsular Gneissic Complex are generally massive, occasionally foliated and rarely gneissic. The rocks are leucocratic showing light grey to grayish pink in colour. The petrographic study of these rocks exhibit equigranular, coarse grained showing perthitic, porphyritic and poiklitic textures. The essential constituents are quartz, K-feldspar (orthoclase, microcline), plagioclase feldspar; minor amount of biotite, apatite and opaques. Microcline is predominant over orthoclase. The microcline phenocrysts have inclusions of quartz and twinned plagioclase with occasional alkali feldspar. The groundmass is composed of quartz, alkali feldspar, plagioclase and biotite with feldspars partially sericitised. The microcline grains at few places are perthitic, partially altered to chlorite observed at places. The plagioclase exhibits perthitic texture and the presence of primary biotite is an evidence for its magmatic source. Secondary muscovite is present as an alteration product of K-feldspar and chlorite. Most of the quartz grains exhibit undulose extinction. The K-feldspar is highly sericitised and contains perthitic lamellae and the contact of plagioclase and K- feldspar is myrmekitic in nature. Recrystallized biotite is present in minor amounts with zircon and opaque’s as accessories. Recrystallized small quartz phenocryst grains are shows thin zoning. It is noticed that even the K-feldspar phenocrysts have been marginally recrystallized. Replacement of K-feldspar by the muscovite and chlorite is observed where the grain boundary is recrystallized. Field photo-1: Epidote vein is intruded in to coarse grained pink granite at Hanumapur. Field photo-2: Granite is intruded by quartz- pegmatite vein at SE Bhongir. Field photo-3: Pegmatitic vein showing intrusive relationship with pink granite at Masireddipalli. Field photo-4: Hornblende grains devoleped along foliation plane in granite at Kondamadugu.
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  Ch.Ramakrishna1 .et al. Int.Journal of Engineering Research and Applications www.ijera.com ISSN: 2248-9622, Vol. 6, Issue 4, (Part - 2) April 2016, pp.57-63 www.ijera.com 59|P a g e Photomicrograph-1: Granite showing altered alkali feldspar at Anjapur [Sample No AJ-1] Photomicrograph-2: Microcline showing crosshatched twinning in Granite at Madhapuram [Sm. No: MA-1] Photomicrograph-3: Perthite showing relict quartz inclusions at Pagidipalli [Sm. No: PP-1] Photomicrograph-4: Microcline showing crosshatched twinning in Granite at Padamatisomaram [Sm. No PS- 2] Photomicrograph-5: Flame perthite in Granite at Padamatsomaram [Sm. No PS-2] IV. SAMPLING AND ANALYTICAL TECHNIQUES A total of 100 samples of granitoids from Bibinagar- Bhongir area in the Nalgonda district were collected. Around 40 thin sections were prepared and studied. Major oxides and trace element compositions were analyzed using X-ray fluorescence spectrometry (XRF) and Inductively Coupled Plasma-Mass Spectrometer (ICP-MS) at the National Geophysical Research Institute (NGRI), Hyderabad. The major oxides include SiO2, Al2O3, Fe2O3, MnO, MgO, K2O, Na2O, TiO2 & P2O5 and the trace elements include Be, Ge, As, Mo, Hf, Ta, W, Bi, U, La, Ce, Pr, Nd, Eu, Sm, Tb, Gd, Dy, Ho, Er, Tm, Yb & Lu. The granites are plotted on an Ab-An-Or diagram of O’Connor, (1965) (Fig -2). The data falls within the granite field while few samples fall in the granodiorite field. Harker diagram (Fig.-3) exhibits decrease in the amount of MgO, TiO2, CaO, P2O5 and total Fe with increase in SiO2.The negative correlation between SiO2 vs CaO, SiO2 vs TiO2 and SiO2 vs MgO indicating plagioclase fractionation as well as differential crystallisation and hence diorite- granodiorite and biotite granite are observed. Fig-2: Granitoids plots in Feldspar triangles diagram (Ab-An-Or) after O’Connor 1965.
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  Ch.Ramakrishna1 .et al. Int.Journal of Engineering Research and Applications www.ijera.com ISSN: 2248-9622, Vol. 6, Issue 4, (Part - 2) April 2016, pp.57-63 www.ijera.com 60|P a g e MultipleplotofSiO2vs.TiO2Al2O3MgOCaONa2OK2OP2O5Fe2O3MnO 60 65 70 75 0.00.20.40.60.81.0 SiO2 TiO2 60 65 70 75 11.011.512.012.513.013.5 SiO2 Al2O3 60 65 70 75 02468 SiO2 MgO 60 65 70 75 123456 SiO2 CaO 60 65 70 75 3.03.54.04.55.05.56.0 SiO2 Na2O 60 65 70 75 12345678 SiO2 K2O 60 65 70 75 0.00.10.20.30.4 SiO2 P2O5 60 65 70 75 01234567 SiO2 Fe2O3 60 65 70 75 0.000.100.200.30 SiO2 MnO MultipleplotofSiO2vs.TiO2Al2O3MgOCaONa2OK2OP2O5Fe2O3MnO Fig.-3: Harker variation diagram of granitoids. V. CLASSIFICATION/TECTONIC ENVIRONMENT Classification of the rock with total alkali silica (TAS), SiO2 vs K2O+Na2O geochemical rock classification diagram of Cox et al (1979) (Fig-4) adapted by Wilson, 1989 for plutonic rocks shows the plots fall mostly in the acid field or to be more specific mostly they falls in granite field and very few bordering diorite and syenite field. The solid curve line sub-dividing the alkaline from the subalkaline rocks. After plotting the TAS vs Silica (Fig-5) by Middlemost (1994) the plots are fall in granite field while few of them falls in quartz monzonite, granodiorite and diorite field. As per the K2O+Na2O; Fe2O3 and MgO plot (Fig-6) it is clear that the rock is rich in K2O+Na2O which means it is alkali granite. The AFM plot (Fig-7) after Irvine and Baragar (1971) suggests the magma to be Calc-alkaline in nature. When the major Oxides data were plotted (Fig-8) in the R1-R2 diagram of De La Roche et al (1980) which is based upon the cation proportions expressed as millications on an X-Y bivariate graph using the plotting parameters R1& R2 where R1 is plotted along the X-axis and is defined by R1=4Si- 11(Na+K)-2(Fe+Ti) and Fe represents the total Fe while the R2 is plotted along the Y-axis and is defined as R2=(Al+2Mg+6Ca), the plots fall in the granite, granodiorite, quartz monzonite, alkali granite and diorite field. The Molar Na2O-Al2O3-K2O plot (Fig-9) shows granitoids are meta-aluminous, alkali rich-calc-alkaline series. Numerous petrogenetic schemes such as Whalen et al. (1987) and Pearce et al. (1984) have been proposed for the origin of the chemically distinctive A-type (Anorogenic Granites). Whalen et al. (1987) has used a factor (10000*Ga/Al) plotted against elements like Nb, Ce, Zr, Y, Zn, (K2O+Na2O), and against ratios K2O/MgO, FeOt /MgO, (K2O+Na2O)/CaO to show discrimination of A-type granite from the general M-, I- and S-type granites. Similarly, he used (Zr+Ce+Y+Nb) against FeOt /MgO and (K2O+Na2O)/CaO to distinguish A- type granite (Fig-10) falls in A- type and volcanic arc granites, syn-collision to late orogenic. Fig-4: SiO2 vs Na2O+K2O binary (TAS, Cox et al.1979) diagram shows majority of samples fall in Granitic field except two of them falls in diorite field. Fig-5: Na2O+K2O vs SiO2 binary (Middlemost, 1994) diagram shows Plots of Granitoids of Bibinagar-Bhongir area. Fig-6: Na2O + K2O, Fe2O3 and MgO plot
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  Ch.Ramakrishna1 .et al. Int.Journal of Engineering Research and Applications www.ijera.com ISSN: 2248-9622, Vol. 6, Issue 4, (Part - 2) April 2016, pp.57-63 www.ijera.com 61|P a g e A M F Tholeiite Series Calc-alkaline Series AFMplotIrvineandBaragar1971 Fig-7: AFM triangular diagram for Granitoids after Irvine and Baragar (1971). A = Wt% Na2O + K2O, F = Wt% FeO+Fe2O3 and M = Wt% MgO recalculated to 100 Fig-8: R1-R2 plot (De la Roche et al. 1980) of granitoids of Bibinagar-Bhongir area. Na2O K2O Al2O3 Sodic Potassic Ultrapotassic Metaluminous Peraluminous Peralkaline Perpotassic MolarNa2O  Al2O3K2Oplot Fig-9: Molar Na2O- Al2O3- K2O plot. 50 500 5000 1310100 A FG OTG Zr+Nb+Ce+Y FeOtMgO 50 500 5000 1310100 AFG OTG Zr+Nb+Ce+Y Na2OK2OCaO 1 3 10 20 131020 A I & S 10000*Ga/Al Na2OK2O 1 3 10 20 110100 A I & S 10000*Ga/Al Na2OK2OCaO 1 3 10 20 110100 A I & S 10000*Ga/Al K2OMgO 1 3 10 20 110100 A I & S 10000*Ga/Al FeOtMgO 1 3 10 20 101001000 I & S 10000*Ga/Al Zr 1 3 10 20 110100 I & S 10000*Ga/Al Nb 1 3 10 20 1101001000 I & S 10000*Ga/Al Ce 1 3 10 20 110100 I & S 10000*Ga/Al Y 1 3 10 20 1101001000 I & S 10000*Ga/Al Zn 1 3 10 20 0.512 I & S 10000*Ga/Al Agpaiticindex PlotstodistinguishA typegranitoidsWhalen1987 Fig-10: Granitoids indicating a type nature (Whalen, 1987) When the granite data was plotted on a Ta vs Yb diagram (Fig-11) using the composition and discriminate fields of Pearce et al (1984) they fell in the Volcanic Arc Granite field and few plots in the syn-collision granite field. The same data i.e. K2O-Fe2O3 vs SiO2 and Fe2O3 vs MgO (Fig -12) plotted in Maniar and Piccoli (1989) which is primarily a major element based on geotectonic classification, it occupied the Island Arc Granite(IAG) + Continental Arc Granite (CAG) + Continental Collision Granite (CCG). 1 10 100 1000 1101001000 ORGVAG WPGsy n-COLG Y+NbRb 1 10 100 1000 1101001000 ORG VAG+ sy n-COLG WPG Y Nb 1 10 100 1101001000 sy n-COLG WPG VAG ORG Ta+Yb Rb 0.1 1 10 100 0.1110100 sy n-COLG WPG VAG ORG Yb Ta GranitetectonicdiscriminationPearceetal.1984 Fig-11: Granite tectonic decimation –Pearce et al. (1984) 60 65 70 75 80 01234567 IAG+CAG+CCG+RRG+CEUG+POG OP SiO2 K2O 70 72 74 76 78 80 1011121314151617 IAG+CAG+CCG RRG+CEUG POG SiO2 Al2O3 60 65 70 75 80 0.50.60.70.80.91 IAG+CAG+CCG POG RRG+CEUG SiO2 FeOtFeOtMgO 0 5 10 15 20 25 30 0102030405060 IAG+CAG+CCG POG RRG+CEUG M AFM FAFM 0 5 10 15 20 25 30 0102030405060 IAG+CAG+CCG POG RRG+CEUG C ACF FACF 0.5 1 1.5 123 Metaluminous Peraluminous Peralkaline A/CNK A/NK GranitetectonicdiscriminationManiarandPiccoli1989 Fig-12: Granite tectonic discrimination- Maniar and Piccoli (1989). VI. RARE EARTH ELEMENTS (REE) The REE pattern of the igneous rock is controlled by the REE chemistry of its source and the crystal melt equilibrium which has taken place during its evaluation. The characteristic chondrite normalized REE pattern of granite (Fig -13) shows strong negative Eu anomaly suggesting early separation of plagioclase by Nakamura (1974). On a spider diagram multi element profiles normalised to primitive mantle as per Sun & Macdonough (1989) the Bibinagar-Bhongir
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  Ch.Ramakrishna1 .et al. Int.Journal of Engineering Research and Applications www.ijera.com ISSN: 2248-9622, Vol. 6, Issue 4, (Part - 2) April 2016, pp.57-63 www.ijera.com 62|P a g e granitoids (Fig -14) patterns showing volcanic arc granite such as the rocks in the region are enriched with large ion lithophile elements (LILE) such as Th, Ba and Rb with a high ionic strength or high field strength elements (HFSE) such as Ti, Y and P show depletion, which is the characteristic of volcanic arc granites. The enrichment of Ce and La in Calc- alkaline and Shonshonitic Series and low value of Y and Yb relative to the normalizing composition indicates the volcanic arc granites. The enhanced level of LILE relative to HFSE in Bibinagar-Bhongir granitoids (Fig-11) points to the subduction zone enrichment and/or crustal contamination of the source region as per Pearce et al (1984). The patterns indicate moderately fractionated LREE and poorly fractionated HREE (Fig- 14). La Pr Pm Eu Tb Ho Tm Lu Ce Nd Sm Gd Dy Er Yb 1101001000 SpiderplotREEchondriteNakamura1974 Sample/REEchondrite Fig-13: Nakamura, N., (1974) Determination of REE. Cs Ba U K Ce Pr P Zr Eu Dy Yb Rb Th Nb La Pb Sr Nd Sm Ti Y Lu 0.010.1110100100010000 SpiderplotNMORBSunandMcDonough1989 Sample/NMORB Fig-14: Sun, S.S., McDonough, W.F., (1989). VII. SUMMARY AND CONCLUSIONS The petrographic study of Granitoids of the Bibinagar- Bhongir area are indicates that of pure magmatic origin in the form of different magmatic textures viz. perthitic, porphyritic, poiklitic textures and presence of many fresh quartz grains. The Granitoids are also showing syntectonic movement. The field evidences viz., the alignment of hornblende along foliation plane, enrichment of biotite at places and migmatisation of magma is evidenced. It was evidenced by petrographic studies also such as, the bent twin lamellae of plagioclase which was developed due to deformation and recrystallisation of quartz grains. The granites plotted on an Ab-An-Or diagram (Fig-2) O’Connor, 1965) is falls within the granite field. Based on classification of the rock with total alkali silica (TAS), SiO2 vs K2O+Na2O geochemical rock classification diagram of Cox et al (1979) (Fig -4), adapted by Wilson,1989 for plutonic rocks, mostly they fall in granite field and very few bordering the diorite and syenite field. The TAS vs Silica (Fig-5) by Middlemost (1994) plot falls in the granite field while few are falling in the granodiorite, quartzmonzonite and diorite field. The granite data was plotted on a Ta vs Yb diagram (Fig-11) using the composition and discriminate fields of Pearce et al (1984) they fell in the Volcanic Arc Granite field and few plots in the syn-collision granite field. The same data i.e. K2O-Fe2O3 vs SiO2 and Fe2O3 vs MgO (Fig -12) plotted in Maniar and Piccoli (1989) which is primarily a major element based on geotectonic classification, it occupied the Island Arc Granite(IAG) + Continental Arc Granite (CAG) + Continental Collision Granite (CCG). The characteristic chondrite normalized REE pattern of granite (Fig -13) shows strong negative Eu anomaly suggesting early separation of plagioclase by Nakamura (1974). The enrichment of Ce and La in Calc-alkaline and Shonshonitic Series and low value of Y and Yb relative to the normalizing composition indicates the volcanic arc granites. The enhanced level of LILE relative to HFSE in Bibinagar-Bhongir granitoids (Fig-11) points to the subduction zone enrichment and/or crustal contamination of the source region as per Pearce et al (1984). REFERENCES [1]. A Manual of the Geology of India, Vol. 1, Pt. 1, Spl. Pub. No. 77, Geol. Surv. Ind., (2006)]. [2]. Swaminath, J., Ramakrishnan, M., 1981. Early Precambrian supracrustals of Southern Karnataka. Geol. Surv. India Memoir 112, 351 p. [3]. Naqvi, S.M., 1981. The oldest supracrustals of the Dharwar Craton, India. J. Geol. Soc. India 22 (10), 458–469. [4]. Naqvi, S.M., Rogers, J.J.W., 1983. Precambrian of South India (based on the Proceedings of the Indo-U.S.Workshop held at Hyderabad,January 12–14, 1982), vol. 4, Geological Society of India, Memoir, p. 575 [5]. V. Divakara Rao,P Rama Rao and MV Subba Rao 1999.The Ghingee grannite,Tamilnadu,South India: Geochemistry and petrogenesis,Gondwana Research, V.2.,No 1,pp 117-126.
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  Ch.Ramakrishna1 .et al. Int.Journal of Engineering Research and Applications www.ijera.com ISSN: 2248-9622, Vol. 6, Issue 4, (Part - 2) April 2016, pp.57-63 www.ijera.com 63|P a g e [6]. Radhakrishna, B.P., 1956. The Closepet Granite of Mysore State, India.Mysore Geological Association (Bangalore) Special Publication, 3, 110 p. [7]. Friend, C.R.L. and Nutman, A.P. (1991). SHRIMP U-Pb Geochronology of the Closepet Granite and Peninsular Gneiss, Karnataka, South India. J. Geol. Soc. India 38, 357-368. [8]. Jayananda, M., Martin, H. and Mahabaleshwar, B. (1992). The mechanisms of recycling of Archean continental crust: example of the Closepet granite, southern India. Proc. 3"I In. Archean Symp.,Perth. 2 13-222. [9]. Jayananda, M., Martin, H., Peucat, J.-J. and Mahabaleshwar, B. (1995). Late Archean crust-mantle interactions: geochemistry of LREE-enriched mantle derived magmas. Example of Closepet batholith, southern India. Contrib. Mineral. Petrol. 1 19,3 14- 329. [10]. Radhakrishna, B.P., 1983. Archaean granite- greenstone terrain of south Indian shield. In: Naqvi, S.M., Rogers, J.J.W. (Eds.), Precambrian of South India, vol. 4. Geological Society of India, Memoir, pp.1– 46. [11]. Radhakrishna, B.P., Naqvi, S.M., 1986. Precambrian continental crust of India and its evolution. J. Geol. 94, 145–166. [12]. Naqvi, S.M., Rogers, J.J.W., 1987. Precambrian geology of India. In: Oxford Monographs on Geology and Geophysics No. 6. Oxford University Press, New York, pp. 223. [13]. Rogers, J.J.W., 1996. A history of continents in the past three billion years. J. Geol. 104, 91–107 [14]. Naqvi, S.M., 2005. Geology and Evolution of the Indian Plate (From Hadean to Holocene—4 Ga to 4 Ka). Capital Publishing Company,New Delhi, pp. 450. [15]. Manikyamba, C., Kerrich, R., Naqvi, S.M., Ram Mohan, M., 2004. Geochemical systematics of tholeiitic basalts from the 2.7 Ga Ramagiri-Hungund composite greenstone belt, Dharwar Craton.Precambrian Res. 134, 21–39. [16]. Manikyamba, C., Naqvi, S.M., Rao, D.V.S., Ram Mohan, M., Khanna,T.C., Rao, T.G., Reddy, G.L.N., 2005. Boninites from the Neo-archaean Gadwal greenstone belt, Eastern Dharwar craton, India: implications for Archaean subduction processes. Earth Planet. Sci. Letters 230 (1), 65-83 [17]. Naqvi, S.M., Khan, R.M.K., Manikyamba, C., Ram Mohan, M.,Khanna, T.C., 2006. Geochemistry of the Neo Archaean high-Mg basalts, boninites and adakites from the Kushtagi-Hungund greenstone belt of the eastern Dharwar craton (EDC); implications for the tectonic setting. J. Asian Earth Sci. 27, 25–44. [18]. O'Connor, J. T. (1965). A classification for quartz-rich igneous rocks based on feldspar ratios. In: US Geological Survey Professional Paper B525. USGS, 79–84 [19]. Wilson, M. 1989. Igneous Petrogenesis. London: Unwin Hyman. [20]. Middlemost, A.K.: 1994, Naming materials in the magma/igneous rock system. Earth- Sci. Reviews 37, 215–224. [21]. Irvine, T. N. & Baragar, W. R. A. (1971). A guide to the chemical classification of the common volcanic rocks. Canadian Journal of Earth Sciences 8, 523–548. [22]. De La Roche, H., Leterrier, J., Grandclaude, P. & Marchal, M. (1980). A classification of volcanic and plutonic rocks using R1R2- diagram and major element analyses – its relationships with current nomenclature. Chemical Geology 29, 183–210. [23]. Whalen, J.B. Currie, K.L. & Chappell, B.W. 1987. Contrib. Mineral. Petrol., 95. 407- 419.Pearce, J.A., Harris, N.B.W., Tindle, A.G., 1984. Trace element discrimination diagrams for the tectonic interpretation of granitic rocks. Journal of Petrology 25, 956– 983. [24]. Lett. 230, 65–83,Maniar, P.D., Piccoli, P.M., 1989. Tectonic discrimination of granitoids. Geological Society of America Bulletin 101, 635–643. [25]. Nakamura, N., 1974. Determination of REE, Ba, Mg, Na and K in carbonaceous and ordinary chondrites. Geochim. Cosmochim. Acta 38, 757-775. [26]. Sun, S.S., McDonough, W.F., 1989. Chemical and isotopic systematic of oceanic basalts: implications for mantle composition and processes. In: Saunders, A.D., Norry, M.J. (Eds.), Magmatism in Ocean Basins, vol. 42. Geological Society Special Publication, 313–345.