Exhumation history of the NW Indian Himalaya revealed by fission track and 40Ar/39Ar ages
Schlup, M. and Steck, A. and Carter, Andrew and Cosca, M. and Epard, J.L. and Hunziker, J. (2011) Exhumation history of the NW Indian Himalaya revealed by fission track and 40Ar/39Ar ages. Journal of Asian Earth Sciences 40 (1), pp. 334-350. ISSN 1367-9120.
New fission track and Ar/Ar geochronological data provide time constraints on the exhumation history of the Himalayan nappes in the Mandi (Beas valley) – Tso Morari transect of the NW Indian Himalaya. Results from this and previous studies suggest that the SW-directed North Himalayan nappes were emplaced by detachment from the underthrusted upper Indian crust by 55 Ma and metamorphosed by ca. 48–40 Ma. The nappe stack was subsequently exhumed to shallow upper crustal depths (<10 km) by 40–30 Ma in the Tso Morari dome (northern section of the transect) and by 30–20 Ma close to frontal thrusts in the Baralacha La region. From the Oligocene to the present, exhumation continued slowly. Metamorphism started in the High Himalayan nappe prior to the Late Oligocene. High temperatures and anatexis of the subducting upper Indian crust engendered the buoyancy-driven ductile detachment and extrusion of the High Himalayan nappe in the zone of continental collision. Late extrusion of the High Himalayan nappe started about 26 Ma ago, accompanied by ductile extensional shearing in the Zanskar shear zone in its roof between 22 and 19 Ma concomitant with thrusting along the basal Main Central Thrust to the south. The northern part of the nappe was then rapidly exhumed to shallow depth (<10 km) between 20 and 6 Ma, while its southern front reached this depth at 10–5 Ma.
|Keyword(s) / Subject(s):||Himalaya, geochronology, Nappe tectonics, Ar–Ar ages, fission track ages|
|School:||Birkbeck Schools and Departments > School of Science > Earth and Planetary Sciences|
|Date Deposited:||27 Jan 2011 11:20|
|Last Modified:||11 Oct 2016 11:55|
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