Large-Scale Geometry, Offset and Kinematic Evolution of The
Available online at www.sciencedirect.com R Earth and Planetary Science Letters 219 (2004) 255^269 www.elsevier.com/locate/epsl Large-scale geometry, o¡set and kinematic evolution of the Karakorum fault, Tibet Robin Lacassin a;Ã, Franck Valli a, Nicolas Arnaud b, P. Herve¤ Leloup c, Jean Louis Paquette d, Li Haibing a;e, Paul Tapponnier a, Marie-Luce Chevalier a, Stephane Guillot c, Gweltaz Maheo c, Xu Zhiqin e a Laboratoire de Tectonique, Me¤canique de la Lithosphe're, UMR 7578 CNRS, Institut de Physique du Globe de Paris, 75252 Paris CX05, France b Laboratoire de Dynamique de la Lithosphe're, UMR 5573 CNRS, ISTEEM - USTL, Place Euge'ne Bataillon, 34095 Montpellier CX5, France c Laboratoire de Dynamique de la Lithosphe're, UMR 5570 CNRS, UCB Lyon et ENS Lyon, 2 rue Dubois, 69622 Villeurbanne, France d Laboratoire Magmas et Volcans, UMR 6524 CNRS, Universite¤ Blaise Pascal, Rue Kessler, 63038 Clermont Ferrand CX, France e Institute of Geology, Chinese Academy of Geological Sciences, 26 Baiwanzhuang Road, Beijing 100037, PR China Received 16 September 2003; received in revised form 18 December 2003; accepted 18 December 2003 Abstract The total offset, lifespan and slip rate of the Karakorum fault zone (KFZ) (western Tibet) are debated. Along the southern fault half, ongoing oblique slip has exhumed dextrally sheared gneisses intruded by synkinematic leucogranites, whose age (V23 Ma, U/Pb on zircon) indicates that right-lateral motion was already in progress in the late Oligocene. Ar/Ar K-feldspar thermochronology confirms that rapid cooling started around 12 Ma, likely at the onset of the present dextral normal slip regime.
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