Geochronology of the initiation and displacement of the Altyn Strike-Slip Fault, western China

40Ar/39Ar dating studies have been carried out along the Dangiin Pass transect across the Altyn Strike-Slip Fault (ASSF). The samples gave ages of 445.2-454.3 Ma in the Northern Belt, 164.3-178.4 Ma in the Mesozoic Shear Zone and 26.3-36.4 Ma in the Cenozoic Shear Zone. Using the piercing point of the Bashikaogong Fault and the Cangma-Heihe Fault an offset of 350-400 kin along the ASSF has been estimated. The 40Ar/39Ar dating of the syntectonic-growth or syntectonic-resetting minerals from the samples within the ASSF belt, and offset estimations from different age piercing points suggest that the ASSF should be initiated in the Middle Jurassic (178.4-160 Ma). Combined with previously reported ages, our studies show that the ASSF is characterized by multi-phase re-activation during 85-100, 25-40 and 8-10 Ma following its initiation in the Middle Jurassic in the regional tectonic setting of convergence between the Indian and Eurasian continents. (c) 2006 Elsevier Ltd. All rights reserved.