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The Madurai block, the largest crustal block in the Precambrian Southern Granulite Terrane of south India, preserves rare assemblages of high- to ultrahigh-temperature metamorphic rocks. These rocks bear exclusive evidence for the high thermal regime prevalent during their formation and can be constrained from accessory phases such as zircon, monazite and garnet. Here, we present the P-T-t evolutionary history of garnet-cordierite-spinel granulites from different localities in the Madurai block. Combined petrography, mineral reaction, geothermobarometry and pseudosection modelling of the samples record HT to near-UHT metamorphic conditions with clockwise P-T trajectories. LA-(MC)-ICPMS U-Pb/Hf isotopic studies on zircons point to Paleoproterozoic high-grade metamorphism in the area with juvenile magmatic signatures. LA-ICPMS/EPMA monazite dating constrains the timing of HT to near-UHT metamorphism at ~580 and ~550 Ma. The heat source required for the Paleoproterozoic high-T event is correlated with the synchronous igneous emplacements reported in the region, whereas the heat source responsible for the Neoproterozoic HT to near-UHT event can be related to the processes associated with crustal thickening and synchronous mafic emplacement. The clockwise P-T trajectories of these granulites are interpreted as the signature of collisional orogeny prevalent in the region during the final stages of Gondwana assembly. [ABSTRACT FROM AUTHOR]

Here, we report petrography, whole-rock geochemistry, and zircon U-Pb geochronology to understand the origin, source, geodynamic setting, and evolution of A-type granite and granite gneiss as well as establish their emplacement age from Mahakoshal Basin. Mineralogically, Sidhi granite gneiss and Madanmahal granite of the Mahakoshal Basin dominantly consist of quartz, K-feldspar, and plagioclase. Geochemically, Sidhi granite gneiss and Madanmahal granite are ferroan in nature. The studied rocks are akin to peraluminous A-type granites and have average zircon saturation temperatures of 955°C and 977°C, respectively. The studied rock types are derived from partial melting of pre-existing crust indicated by (Y/Nb)N >0.18, (Th/Nb)N >2, (Ce/Pb)N <1, and (La/Nb)N >2 accompanied by the Eu, Ba, Sr, Ti, and Nb negative anomalies. The zircon U-Pb geochronology yielded emplacement ages of 1723 ± 16 Ma for the Sidhi granite gneiss and 1801 ± 64 Ma for the Madanmahal granite. Based on similar geochemical characteristics such as rare earth element patterns, Eu anomalies, and Ce/Pb, La/Nb, and Th/Nb ratios, we propose that the Sidhi granite gneiss and Madanmahal granite are derived from the same source i.e. Bundelkhand gneisses and granites, and formed in a post-orogenic rift environment of the accretionary orogen setting. [ABSTRACT FROM AUTHOR]