Neoproterozoic Felsic Volcano-plutonic Rocks, Tusham Ring Complex, Malani Igneous Suite, NW Indian Shield: Petrogenetic Modeling, Magmatic Source and Geodynamic Evolution

This paper reports petrogenetic modelling and geodynamic evolution of felsic volcano-plutonic rocks of Riwasa and Nigana areas from Tusham Ring Complex (TRC), NW Indian shield and also discusses their geochemical characteristics to understand the possible magmatic source. These granitoids are identified with hypersolvus, high-K calc-alkaline to shoshonitic series, peraluminous, ferroan, typical A-type affinity and anorogenic genesis. The investigated rocks are enriched in SiO2, Na2O + K2O, REEs (except Eu), LILE + HFSE, halogens (F and Cl), depleted in CaO, MgO, Sr, Cr, Ni, P, Ti, V and Eu abundances and have elevated Fe/Mg, Ga/Al, Th/U, A/CNK ratios. The elemental geochemistry in conjunction with petrogenetic modelling (batch melting plus fractional crystallization) suggests that the felsic volcano-plutonic rocks of TRC were derived from a source similar to 12% partial melting of Nathwara tholeiitic basalt leaving a residue with (80% plagioclase, 5% orthoclase, 5% clinopyroxene, 5% orthopyroxene and 5% hornblende), 9% partial melting of Kundal basalt leaving a residue with (67% plagioclase, 13% orthoclase, 8% clinopyroxene, 7% orthopyroxene and 5% hornblende), 5% partial melting of Mesoproterozoic plagioclase amphibolite of southwestern Yangtze Block leaving a residue with (79% plagioclase, 4% orthoclase, 4% clinopyroxene, 9% orthopyroxene and 4% hornblende) and 15% fractional crystallization of least evolved felsic volcanic rocks leaving a residue with (60% plagioclase, 20% clinopyroxene, 5% hornblende and 5% magnetite). In this study, we also propose that the tectonic-magmatic activities that occurred in TRC are closely related to Neoproterozoic magmatism of NW India (Malani Igneous Suite-MIS), South China (SW Yangtze Block), NW Vietnam (Phan Si Pan Zone), SE Pakistan (Nagarparkar Igneous Complex), Seychelles and Madagascar.