Tectonic evolution of the neoproterozoic tusham ring complex, Northwestern India: Constraints from geochemistry and zircon U–Pb geochronology, and implications for Rodinia supercontinent history

Neoproterozoic felsic magmatic suites are important proxies to investigate the breakup history of the Rodinia supercontinent which likely coincided with the emplacement of voluminous Silicic Large Igneous Provinces (SLIPs). Here we report new zircon U–Pb ages with comprehensive whole-rock and mineral chemistry data on the felsic volcano-plutonic rocks from the Tusham Ring Complex (TRC) that forms part of the anorogenic Malani Igneous Suite (MIS) (∼780–750 Ma) in NW India. The plutonic rocks (granites) and contemporaneous volcanic rocks (rhyolites) show affinity to A-type granitoids, hypersolvus to subsolvus, and metaluminous to peraluminous. The granitoids investigated in this study are enriched in SiO2, Na2O + K2O, Fe/Mg, Ga/Al, U, Th, REE (except Eu), and depleted in MgO, CaO, Cr, Ni, P, Ti, Sr, and Eu contents. The zircon U–Pb dating for felsic volcanic rocks (four rhyolite samples) yielded Neoproterozoic ages ranging from 827 to 764 Ma whereas zircon in five felsic plutonic rocks (granite) shows ages ranging from 830 to 787 Ma, indicating coeval nature of the intrusive and extrusive rocks. The zircon grains have mostly negative εHf(t) values up to −3.62 and yield crustal Hf model ages from 1.6 Ga to 1.9 Ga, suggesting that the magmatic event involved melting of a Paleoproterozoic source. Based on geochemical features, we propose that the partial melting of crustal protoliths, fractional crystallization, and crustal contamination played a significant role in the magmatic evolution of these rocks. We also infer that the felsic anorogenic magmatism in the TRC occurred in an extensional tectonic regime, possibly associated with a mantle plume event. Our results, in conjunction with previous studies, support the model of anorogenic magmatism linked with the disruption of the Neoproterozoic Rodinia supercontinent.