Abstract: The Upper Cretaceous Jingzhushan Formation in the Coqen region,Xizang is arranged along the Bangong Lake-Nujiang suture zone,Qiekan-Goicang-Asog fault and northern Taro Lake-southern Dawa Lake-Qiucuomai depression zone.Lithologically,the Jingzhushan Formation is made up of a suite of purplish red molasse clastic rocks which were laid down in the fan delta and delta environments.The progradational directions indicated by the foreset beddings in these environments suggest an early provenance from the north and an additional late provenance from the south.The development of the molasses deposits in the Jingzhushan Formation has provided a convincing orogenic evidence of the Bangong Lake-Nujiang suture zone.