Isotopic and geochemical studies of Proterozoic to Recent Earth processes: Results from Indian lamproites, massif anorthosites and Vindhyan sediments, western Anatolian volcanics, Nyiragongo volcano in the African rift, Lonar impact crater in the Deccan

This study utilizes isotopic and geochemical tools to investigate Proterozoic crust-mantle processes in India (Part-I), Cenozoic to recent volcanism in western Anatolia and the Fast African Rift (Part-II), meteoritic impact on basalts and diagenesis of black shales (Part-III).; Part-I. A combined major, trace element and Nd-Sr-Hf-Pb isotopic study of rare Proterozoic lamproites from eastern India provides evidence of their origin from melting of subducted Archean komatiite in a mantle peridotite source.; Chilka massif anorthosites of eastern India formed at ∼855 Ma by melting of lower crust with minor contributions from depleted mantle due to rifting associated with the breakup of the Supercontinent Rodinia.; Trace elements and Nd-isotopes indicate sediment sources of the mid-Proterozoic Vindhyan basin in India from an extinct Andean-type are. Sedimentation in this basin, was initiated in a foreland setting that lasted for ∼1000 Ma. with at least three discontinuities.; Part-II. Calc-alkaline volcanism in Western Anatolia was a result of mantle wedge melting assisted by slab delamination and slab tear in the north and south, respectively. Shoshonitic Kula volcanism resulted from Aegean extension. There is Nd-isotopic evidence of an Atlantic-type suboceanic astllenosphere beneath the western Anatolian micro-plate.; Volcanism in Nyiragongo and Nyamuragira in the east African rift is a result of plume-asthenosphere interaction. Isotopic and geochemical differences in lava compositions from spatially adjacent, simultaneously erupting volcanoes indicate differences in the degrees and depths of partial melting of a heterogeneous phlogopite-bearing carbonated eclogite-peridotite source assemblage. U-Th series disequilibria indicate recent melting of this source and rapid upwelling of the magma.; Part-III. Trace element and Nd-Sr-Ph isotopic study of impact breccia and target basalts from the Lonar crater in India suggests that the Archean basement beneath the target Deccan basalts were also mobilized upon impact.; Source heterogeneity is indicated by the Nd-isotopic compositions of immature black shales, while diagenesis caused variations in Nd-isotopes of mature and post mature Utica shales. North America. The Taconic Foreland Basin hosting the Utica Shale Magnafacies was connected to the global ocean during the time of deposition and sediments were derived from pre-Grenvillean age rocks.