Plate velocity exhumation of ultrahigh-pressure eclogites in the Pakistan Himalaya
Parrish, Randall R; Gough, SJ; Searle, MP; Waters, DJ. 2008 Plate velocity exhumation of ultrahigh-pressure eclogites in the Pakistan Himalaya. Geology, 34 (11). 989-992. 10.1130/G22796A.1Full text not available from this repository.
U-Pb ages of zircon and allanite from the coesite-bearing ultrahigh-pressure (UHP) units in the Kaghan Valley, northern Pakistan, demonstrate that peak UHP metamorphism along the northern margin of the Indian plate occurred at 46.4 ± 0.1 Ma at peak pressure-temperature conditions of >27.5 kbar (>100 km) and 720–770 °C. Much lower pressure retrogressive growth of titanite took place between 46.4 and ca. 44 Ma, indicating that the eclogites were exhumed to 35 km depth at or before 44 Ma, implying very rapid exhumation rates within the mantle of 30–80 mm/yr or more, comparable to rapid plate velocities. Once entrained in the base of the crust, the eclogites followed a slower cooling history from 45 Ma, similar to the amphibolite facies gneisses of the Pakistan Himalaya.
|Programmes:||BGS Programmes 2008 > NERC Isotope Geoscience Laboratory|
|Additional Keywords:||Himalayas, Pakistan, BGSPAP, Metamorphism, ultrahigh-pressure metamorphism • exhumation • allanite • UTh-Pb dating • zircon • coesite • continental collision|
|NORA Subject Terms:||Earth Sciences|
|Date made live:||28 Jul 2009 15:11|
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