HR: 0800h
AN: T51A-0308    [Abstracts]
TI: Arc-continent collision in the Southern Urals
AU: * Brown, D
EM: dbrown@ija.csic.es
AF: Institute of Earth Sciences "Jaume Almera", CSIC, c/Lluis Sole i Sabaris, Barcelona, 08028, Spain
AB: The transition from intraoceanic subduction to arc-continent collision in the Southern Urals of Russia is arguably one of the best-preserved examples in any Paleozoic orogen. The arc-continent collision history recorded in the rocks of the Southern Urals began in the Early Devonian with the onset of intra-oceanic subduction and the formation of the Magnitogorsk Arc and ended with its collision with the margin of Laurrusia during the Late Devonian. Arc-continent collision led to the development of an accretionary complex that includes shallowly and deeply subducted continental margin rocks, ophiolite fragments, and sediments that were deposited in a foreland-basin setting. Data from high pressure rocks preserved in the accretionary complex indicates that at the same time as new arc crust was being added to the continent its margin was being subducted beneath the accreting arc to a depth of at least 60 km and perhaps as much as 120 km or more. Geophysical datasets indicate that the Eurasian continental crust currently reaches a maximum thickness of 53 km beneath the Uralides, with normal mantle P-wave and S-wave velocities below a well defined refraction Moho. This suggests that any of the Laurrusia margin that was subducted to current sub-Moho depths (53 km) has been assimilated into the mantle and its identity as continental crust destroyed.
DE: 8100 TECTONOPHYSICS
DE: 8104 Continental margins: convergent
SC: Tectonophysics [T]
MN: 2007 Fall Meeting