Two-stage evolution of the Altyn Tagh Fault during the Cenozoic: new insight from provenance analysis of a geological section in NW Qaidam Basin, NW China

Terra Nova, 24, 387395, 2012 Abstract We analysed provenance of conglomerate in a geological section spanning late Eocene to Pliocene using the gravel-count method in the NW Qaidam Basin, NW China. The result indicates that the clasts were all derived from the Altyn Mountain to the north with a sudden alteration at ca. 15 Ma, and supports a two-stage evolution model for the Cenozoic Altyn Tagh Fault (ATF) highlighting the history prior to the initiation of left-slip movement on the ATF. During the first stage of ca. 3615 Ma, the ATF was a basal shear zone confined in the middle lower crust and created obvious uplift of the Altyn Mountain. During the second stage since ca. 15 Ma, the crust beneath the Altyn Mountain was eventually split, and left-slip movement on the ATF then initiated.