Metamorphic P-T path of the eastern Trivandrum Granulite Block, southern India : implications for regional correlation of lower crustal fragments

概要

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We report here the metamorphic P-T path for granulite-facies metapelites from the eastern part of the Trivandrum Granulite Block (TGB), southern India, and compare with the paths from the western part of the block as well as from other granulite blocks and shear zones in this region for understanding of exhumation history of the southern granulite terrane. The peak temperature condition of the eastern part (900-1000 °C) is almost consistent with that from the western part, suggesting regional ultrahigh-temperature (UHT) metamorphism throughout the TGB. However, there is a slight difference in peak pressure conditions between the eastern part (12 kbar) and the western part (10 kbar) estimated from different Zn content within spinel in equilibrium with quartz. Such P ∼ 12 kbar high-pressure event is consistent with that obtained from granulite-facies rocks further north in the Palghat-Cauvery Shear Zone system (PCSZ) and Madurai Granulite Block (MGB). The results therefore suggest that the TGB, MGB, and PCSZ underwent similar prograde high-pressure metamorphism followed by peak UHT event along a clockwise P-T trajectory, related to the collisional orogeny during the assembly of the Gondwana Supercontinent.
日本鉱物科学会の論文
2008-08-01