naa a22 4500 510755968 CHVBK 20180411083122.0 cr unu---uuuuu 180411e20130201xx s 000 0 eng 10.1007/s12594-013-0020-z doi (NATIONALLICENCE)springer-10.1007/s12594-013-0020-z Sesha Sai V. Petrology Division, Geological Survey of India, Training Institute, 500 068, Hyderabad, India aut Proterozoic granite magmatism along the terrane boundary tectonic zone to the east of Cuddapah basin, Andhra Pradesh — petrotectonic implications for precambrian crustal growth in Nellore schist belt of eastern Dharwar craton [Elektronische Daten] [V. Sesha Sai] The area adjoining the western part of Archaean Nellore schist belt and the eastern margin of the Proterozoic Cuddapah basin in south Peninsular India is marked by emplacement of a number of granite plutons of Proterozoic age, intermittently extending over a stretch of 350 km from Vinukonda in the north to Sri Kalahasti in the south. Vinukonda, Darsi, Podili and Anumalakonda plutons are intensely deformed particularly along the margins, while development of crude deformational fabric is noticed in Kanigiri, Rapur and Kayyuru-Vendodu plutons. Petrographically majority of these granites vary from alkali feldspar granite to granite with the exception of Rapur granite which varies from granite to granodiorite. Geochemically they exhibit calc-alkaline trend and in A/NK-A/CNK plot they are positioned at the juncture of peraluminous-metaluminous-peralkaline field. Characteristically, majority of these granites are fluorite bearing. Biotite mineral chemistry suggests high FeOT contents (31.68 to 34.69 %) and very low MgO contents (0.49 to 2.41 %). Geochemically, these are charecterised by high SiO2 (69 to 74.5 %), Na2O+K2O (8.19 to 10.11%), Zr (280-660ppm), Y (70-340 ppm), Rb content (180-370 ppm) and high REE contents (except Eu); and low CaO (0.01 to 1.99), MgO (0.01 to 0.92%) and Sr (10 ppm to 85 ppm) contents. Rare earth element studies reveal a general enrichment of LREE, pronounced negative Eu anomaly; flat and depleted HREE. Enriched LILE and HFSE contents; presence of fluorite and interstitial biotite indicate that these granites are crystallized from a fluorine saturated magma derived from enriched crustal source. The field setup, distinct mineralogy and chemical characteristics suggest that these granite plutons are emplaced along a major tectonic zone i.e. terrane boundary shear zone (TBSZ) in a late-orogenic to anorogenic tectonic setup, close to the vicinity of a collision boundary zone; western margin of NSB and eastern margin of Nallamalai Fold Belt (NFB). The Proterozoic granite magmatism reported in the present studies represents a significant event of Precambrian crustal growth at the juncture of two tectonically contrasting terranes i.e. the Archaean Nellore schist belt and the Proterozoic Cuddapah basin in eastern Dharwar craton. Geological Society of India, 2013 Granite magmatism nationallicence Proterozoic nationallicence Nellore schist belt nationallicence Cuddapah basin nationallicence Eastern Dhawar craton nationallicence Andhra Pradesh nationallicence Journal of the Geological Society of India Springer-Verlag 81/2(2013-02-01), 167-182 0016-7622 81:2<167 2013 81 12594 https://doi.org/10.1007/s12594-013-0020-z text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s12594-013-0020-z text/html Onlinezugriff via DOI NATIONALLICENCE 100 1- Sesha Sai V. Petrology Division, Geological Survey of India, Training Institute, 500 068, Hyderabad, India aut NATIONALLICENCE 773 0- Journal of the Geological Society of India Springer-Verlag 81/2(2013-02-01), 167-182 0016-7622 81:2<167 2013 81 12594 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer