Geochronology of granulitized eclogite from the Ama Drime Massif: Implications for the tectonic evolution of the South Tibetan Himalaya

摘要: [1] The Ama Drime Massif (ADM) is an elongate north-south trending antiformal feature that extends ∼70 km north across the crest of South Tibetan Himalaya and offsets position Detachment system. A detailed U(-Th)-Pb geochronologic study granulitized mafic eclogites associated rocks from footwall ADM yields important insights into middle to late Miocene tectonic evolution Himalayan orogen. The igneous precursor 986.6 ± 1.8 Ma was intruded paleoproterozoic (1799 9 Ma) orthogneiss, latter being similar in age previously assigned Lesser Series foreland. original eclogite-facies mineral assemblage has been strongly overprinted by granulite facies metamorphism at 750°C 0.7–0.8 GPa. In host event correlated with synkinematic sillimanite-grade muscovite dehydration melting. Monazite xenotime ages indicate anatexis occurred <13.2 1.4 Ma. High-grade followed postkinematic leucogranite dyke emplacement 11.6 0.4 This integrated data set indicates high-temperature metamorphism, decompression, exhumation postdates mid-Miocene south directed midcrustal extrusion kinematically linked orogen-parallel extension.