HR: 0800h
AN: T51A-0295    [Abstracts]
TI: Multi-Stage origin of the ophiolites along the Bangong-Nujiang suture zone: Implications for the evolution of central Tibet
AU: * Wang, W
EM: weiliang@hkusua.hku.hk
AF: Department of Earth Sciences, University of Hong Kong, Pokflam Road, Hong Kong, 852, China
AU: Aitchison, J C
EM: jona@hku.hk
AF: Department of Earth Sciences, University of Hong Kong, Pokflam Road, Hong Kong, 852, China
AB: The history of the BNS ophiolite is important for models of the tectonic evolution of Central Tibet during the Mesozoic. Current petrologic, geochemical, and stratigraphic data all favor the interpretation of the ophiolite as having formed in a transitional MORB-IAT setting above a supra-subduction zone. Detailed studies of field relationships at several localities indicate that two distinct ophiolitic suites are present, especially in the western and middle sectors of the suture zone. One suite includes all elements of an entire ophiolite sequence albeit dismembered or disrupted through faulting. These rocks are mainly scattered along the northern part of the BNS, e.g. at Bangong Tso, Dong Tso and Dongqiao-Amdo. Radiometric ages for this ophiolitic suites are limited to the Early to Middle Jurassic. The other zone of ophiolitic rocks is located in the southern part of the BNS, such as Shiquanhe, Guchang, Lagkor Tso, Baila-Jueweng and Xainza, and is associated with a remnant basin allowed the deposition of Upper Jurassic to Lower Cretaceous cherts along the south part of the suture, and shallow marine deposition continued on the structural highs elsewhere along the suture.
DE: 1031 Subduction zone processes (3060, 3613, 8170, 8413)
DE: 3022 Marine sediments: processes and transport
DE: 8170 Subduction zone processes (1031, 3060, 3613, 8413)
DE: 8175 Tectonics and landscape evolution
DE: 8185 Volcanic arcs
SC: Tectonophysics [T]
MN: 2007 Fall Meeting