R8: Metamorphic rocks and tectonics

[R8-03] U-Pb geochronology and metamorphic history of gneissic rocks from Sarwar-Junia fault zone, Rajasthan, NW India: Implications for the tectonothermal evolution of the Aravalli-Delhi Mobile Belt

*Junya Okazaki¹, Kaushik Das¹, Anupam Chattopadhyay², Jun-ichi Ando¹, Arindam Sarkar² (1. Hiroshima Uni. Sci., 2. Dehli Uni.)

Keywords:Sarwa-Junia Fault Zone, Metamorphic history, Granitic and Pelitic gneisses, Tectonics of the Aravalli-Delhi Mobile belt, Age of faulting

The gneisses of study area recorded two phases of metamorphism. The first metamorphism (M₁) occurred at ca. 1740 Ma. Subsequently, the second metamorphism (M₂) occurred at ca. 950 Ma. The M₂ peak stage condition reached ~ 850 ℃ temperature at ~ 7 kbar pressure and subsequently, slow near-isobaric cooling occurred. As subsequent event(s), the presence of pseudotachylyte veins indicate the brittle faulting. Such faulting is considered to have occurred between ca. 750 Ma and ca. 905 Ma.