naa a22 4500 510755976 CHVBK 20180411083122.0 cr unu---uuuuu 180411e20130201xx s 000 0 eng 10.1007/s12594-013-0022-x doi (NATIONALLICENCE)springer-10.1007/s12594-013-0022-x Geology and geochemistry of archaean felsic metavolcanic rocks of the Eastern Part of the Kolar greenstone belt, Dharwar craton, India: Implications for their petrogenesis and geodynamic setting [Elektronische Daten] [A. Ugarkar, S. Solankar, V. Vasudev] In the Kolar greenstone belt of the Dharwar craton, felsic metavolcanics are encountered prominently in its eastern region around Surapalli and Marikoppa. These felsic volcanic rocks are essentially homogeneous and their bulk mineralogy is almost the same. They consist of phenocrysts of quartz and feldspar, set in a fine-grained quartzo-feldspathic groundmass. They are calc-alkaline rhyolite in composition, and are characterized by high SiO2 (av. 75.74 wt.%), moderate Al2O3 (av. 11.84 wt.%), Na2O (av. 3.55 wt.%), K2O (av. 3.26 wt%) contents and low Mg# (av. 6.07), Cr (av. 8 ppm), Ni (av. 8 ppm), Sr (av. 331 ppm.), Y (av. 7 ppm), Yb (av. 0.87 ppm) and Nb/Ta (av. 6.40) values, suggesting Tonalite-Trondhjemite-Granodiorite (TTG) affinity for these felsic volcanics. They are strongly fractionated [(La/Yb)N− = 14.41-48.70] with strong LREE enrichment [(La/Sm)N = 2.50-3.59] and strong HREE depletion [(Gd/Yb)N = 1.34-2.77] with positive Eu anomaly. The regional geological set-up, petrographic and geochemical characteristics suggest that these felsic volcanics probably were derived by partial melting of a subducting basalt slab at shallow depth without much involvement of mantle wedge in an island arc geodynamic setting. Geological Society of India, 2013 Felsic volcanism nationallicence Champion gneiss nationallicence Geochemistry nationallicence Petrogenesis nationallicence Geodynamics nationallicence Kolar greenstone belt nationallicence Dharwar craton nationallicence Karnataka nationallicence Ugarkar A. Department of Geology, Karnatak University, 580 003, Dharwad, India aut Solankar S. Department of Geology, Karnatak University, 580 003, Dharwad, India aut Vasudev V. Geomysore Services (India) Pvt. Ltd., 120/45, III Block, 6th Cross, 6th Main, Tyagarajanagar, 560 028, Bangalore, India aut Journal of the Geological Society of India Springer-Verlag 81/2(2013-02-01), 192-202 0016-7622 81:2<192 2013 81 12594 https://doi.org/10.1007/s12594-013-0022-x text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s12594-013-0022-x text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Ugarkar A. Department of Geology, Karnatak University, 580 003, Dharwad, India aut NATIONALLICENCE 700 1- Solankar S. Department of Geology, Karnatak University, 580 003, Dharwad, India aut NATIONALLICENCE 700 1- Vasudev V. Geomysore Services (India) Pvt. Ltd., 120/45, III Block, 6th Cross, 6th Main, Tyagarajanagar, 560 028, Bangalore, India aut NATIONALLICENCE 773 0- Journal of the Geological Society of India Springer-Verlag 81/2(2013-02-01), 192-202 0016-7622 81:2<192 2013 81 12594 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer