HR: 1340h
AN: T53A-0469    [Abstracts]
TI: Continental Collision Model Development: Example from Kohistan, NW Himalayas
AU: * Khan, S D
EM: sdkhan@mail.uh.edu
AF: Department of Geosciences, University of Houston, Houston, TX 77204-5007 United States
AU: Walker, D J
EM: jdwalker@ku.edu
AF: Departemnt of Geology, University of Kansas, Lawrence, KS 66045-7613 United States
AU: Shah, M T
EM: tahir_shah56@yahoo.com
AF: NCE in Geology, University of Peshawar, Peshawar, 25120 Pakistan
AU: Stockli, L
EM: lstockli@ku.edu
AF: Departemnt of Geology, University of Kansas, Lawrence, KS 66045-7613 United States
AB: In order to develop a comprehensive model for the processes involved in continental collision and accretion, it is essential to integrate data and models from a wide variety of disciplines. Studies of the spatial-temporal compositional relationships of post collisional magmas in this regard are very valuable. We are therefore examining the evolution of the Kohistan lithosphere by studying the timing of tectonic and magmatic events, and mantle enrichment-depletion history. A model for the evolution of Kohistan and its interaction with Karakoram and Indian plates will serve to better understand Himalayan orogeny. It is widely accepted that the drift of India was coeval with the development of the Kohistan arc, which collided with Asia along the Shyok Suture, sometime between 75 and 95 Ma (ago). The southern margin of Asia including the Kohistan arc, then became an Andean-type convergent margin that lasted for 20-40 million years, until India collided with Asia. Thrusting of the Kohistan terrane south-ward over the north Indian margin along the Main Mantle Thrust (MMT) was started by 55 Ma. On the basis of the K/Ar and 40Ar/39Ar ages, some authors concluded that the calc-alkaline volcanism, the Utror and Teru Volcanic Formations, continued until 55 Ma. These widely accepted views are inconsistent with our findings on two samples of relatively young 40Ar/39Ar ages for the Teru Volcanic Formation, which suggests that volcanism continued until at least 33 Ma. This interpretation conflicts with earlier models that classify these rocks as pre-collisional. Results giving evidence for the presence of post-collisional volcanic event(s) in Kohistan might indicate previously unrecognized widespread volcanic activity throughout the Himalayas after the collision of the Indian plate with Asia.
DE: 4825 Geochemistry
DE: 5475 Tectonics (8149)
DE: 1744 Tectonophysics
DE: 1035 Geochronology
DE: 1640 Remote sensing
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting