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TitleEocene deep crust at Ama Drime, Tibet: early evolution of the Himalayan orogen
AuthorKellett, D AORCID logo; Cottle, J MORCID logo; Smit, M
SourceLithosphere vol. 6, no. 4, 2014 p. 220-229, Open Access logo Open Access
Alt SeriesEarth Sciences Sector, Contribution Series 20120286
PublisherGeological Society of America
Mediapaper; digital; on-line
File formatpdf; html
AreaAma Drime; Kharta; India
Lat/Long WENS 87.1667 87.8333 28.5000 28.0000
Subjectstectonics; geochronology; Eocene; orogenesis; orogenic regions; tectonic interpretations; tectonic evolution; tectonic setting; metamorphism; zircon; zircon dates; radiometric dating; uranium lead dating; Cenozoic
Illustrationslocation maps; cross-sections; photomicrographs; plots; tables
ProgramGEM: Geo-mapping for Energy and Minerals GSC Science Laboratory Network
Released2014 08 01
AbstractTiming of garnet growth in deep-crustal rocks exposed in the Ama Drime massif of southern Tibet was constrained by Lu-Hf dating. Garnet from three mafic granulitized eclogites, hosted by the Ama Drime felsic orthogneiss, yielded 36.1 ± 1.9 Ma, 37.5 ± 0.9 Ma and 34.1 ± 0.8 Ma. These ages are the oldest reported from the central-eastern Himalaya for deep burial of the Indian lower crust beneath Tibet, and demonstrate that this process started as early as the Eocene following the collision of India and Asia. Unlike the ultra-high pressure eclogites of the northwest Himalaya, the Ama Drime eclogites were not rapidly exhumed as a cold slab, but spent >20 million years in the lower and middle crust before being exhumed to shallow crustal levels in the mid- to late-Miocene.

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