Timescales of Partial Melting and Melt Crystallization in the Eastern Himalayan Orogen: Insights From Zircon Petrochronology

Revealing the timescales of metamorphic and anatectic processes is central to our understanding tectonic evolution collisional orogens. High-temperature migmatites leucogranites are well exposed in Himalayan orogenic core, making it an ideal region study timing duration partial melting melt crystallization orogen. Here, we report integrated comprehensive data set petrography, U-Pb age, trace element for zircon from a pelitic granulite associated leucosomes Greater Sequence (GHS) Yadong area, eastern Himalaya. Zircon grains with complex internal structure retain variable ages ranging 32 Ma 13 that correlate systematically changes concentrations Y, Th, U, Hf, Nb, Ta, HREE, ratios Th/U, Eu/Eu*, Nb/Ta. Combined petrologic analysis, conclude witnessed high-temperature metamorphism, melting, over ?20 Myr. Prograde, simultaneous increases pressure temperature dehydration began at least by ?32 lasted until ?24 Ma. Subsequent quasi-isothermal decompression-melting occurred between ?22 19 Ma, late spanned ?19 Large volumes generated during prograde metamorphism could have triggered exhumation GHS rocks, increasing fraction through positive feedback melting. More analysis different rock types led more complete interpretations Yadong-Sikkim might enable alternate elsewhere Himalayas.