Proterozoic Alkaline rocks and Carbonatites of Peninsular India: A review

Abstract

African orogeny events. Whereas clinopyroxene, amphibole, titanite and apatite fractionation seems to have affected the nephelinite, nepheline syenite and syenite, carbonatite is affected by fractionation of calcite, dolomite, ankerite, pyroxene, apatite, magnetite, mica, and pyrochlore. Trace elements and Sr-Nd-Pb-C-O isotopic compositions of these ARCs strongly suggest a subcontinental lithospheric mantle source, that is enriched either by distribution of subducted crustal material or by metasomatism of mantle-derived fluids, for the generation of ARCs. Despite some isotopic variability that can result from crustal contamination, a trend showing enrichment in 87 Sr/ 86 Sr i (0.702 to 0.708) and depletion in ε Nd(i) (-1.3 to -14.1) over a 2 Gyr duration indicates temporal changes in the lithospheric/ asthenospheric source of ARCs, due to periodic enrichment of the source by mantle-derived fluids. ARC generation starts in an intracontinental rift setting (beginning of Wilson cycle). These early-formed ARCs are carriedto 100 km depths during continental collision (termination stage of Wilson cycle) and undergo extensive

Petrogenesis of a nepheline syenite from parts of the Chotanagpur Granite Gneissic Complex: implications for Neoproterozoic crustal extension in the East Indian Shield

“…We therefore presume that the composition of the magmatic protolith of the studied rock did not change significantly at the scale of the hand specimen. Our study, thus, corroborates the view of published work that the magmatic characters are retained in the studied rock (Upadhyay & Raith, 2006;Upadhyay et al 2006b,c;Burke et al 2008;Ashwal et al 2016;Paul et al 2020).…”

“…It has been mentioned earlier that three so far reported occurrences of alkaline rocks (including this study) and two occurrences of carbonatite are located along two prominent shear zones, the NPSZ and SPSZ, in the CGGC (Fig. 1; Bhaumik et al 1990;Basu, 1993Basu, , 2003Acharyya et al 2006;Goswami & Bhattacharyya, 2008;Goswami & Basu, 2013;Chakrabarty et al 2016;Das et al 2017Das et al , 2019Paul et al 2020). These alkaline rocks and carbonatite share features that signify that the magmatic protoliths of these rocks were emplaced within the granulite crust of the CGGC (in the NPSZ and part of the SPSZ) and were subsequently deformed and metamorphosed.…”

“…The Palaeoproterozoic Indian shield subsequently broke up and reassembled in the subsequent supercontinent cycles (Rodinia and Gondwana; reviewed in Meert & Torsvik, 2003;Brown, 2007;Li et al 2008;Bhowmik et al 2012;Sengupta et al 2015;Dasgupta et al 2013a;Chattopadhyay et al 2015;Olierook et al 2019). The Indian shield including the CGGC has been punctured by multiple phases of alkaline magmatism with or without carbonatite (reviewed in Paul et al 2020) and kimberlite/lamproite/lamprophyre (reviewed in Chalapathi Rao et al 2004Rao et al , 2012Rao et al , 2020Rao et al 2016;Sharma et al 2019) that spread over a long stretch of time after the formation of the Indian shield as a part of the Columbia supercontinent. Geochemical and radiogenic isotope data from >1000 Ma kimberlite/lamproite/lamprophyre and the entrained perovskite support the existence of a metasomatized SCLM where DM was the chief component with variable contributions from the asthenospheric mantle (Rao et al 2016;Sharma et al 2019).…”

“…14). Paul et al (2020), in their exhaustive analyses of published data on the Indian DARs/ DARCs, compiled the ages of emplacement of the magmatic protoliths and the metamorphism of these rocks. We have plotted these data in Figure 14 using the following filters: (1) Only the dates that are based on U-Pb and Sm-Nd systematics are considered; this will ensure interpretation of the DARs/DARCs in the context of supercontinent cycles.…”

Composition and genesis of albitite-hosted antecrystic pyrochlore from the Sevattur carbonatite complex, India

“…Twenty-six major carbonatite complexes have been reported from the Indian subcontinent (Krishnamurthy, 2019; Paul et al , 2020; Randive and Meshram, 2020). Among these, the Cretaceous Amba Dongar, Gujarat; the Tertiary Sarnu-Dandali complex, Rajasthan and the Neoproterozoic Sevattur (also known as Sevathur) alkaline-carbonatite complex are known for the commercial mining of fluorite, REE and vermiculite, respectively (Viladkar and Subramanian, 1995; Palmer and Williams-Jones, 1996; Bhushan and Kumar, 2013; Bhushan, 2015).…”