Abstract: Some advances in stratig raphy and paleontology have been made in the 1:250000 regional geological survey in the Coqen district, Xizang. Abundant foraminiferal fossils were discovered in the upper part of the "Wuyu Group" originally assigned to the continental deposits during the Pliocene. Acco rding to the foraminifera assemblages, the Group should be ascribed to the Aptian-Cenom anian littoral-neritic deposits. The discovery of plenty of silicified wood for the first time in the brecciated tuffs of Early Cretaceous and early Late Cretaceous age has disclosed that the climates were tem perate and humid, and a vast area of forests were destroyed by frequent volcanic eruption in Xizang during these periods. T here occur different fossil com munities in the Lower Permian strata on both sides of the Lagkor lake-Chuanba fault:the coral-fusulinid comm unity in the shallower neritic environments on the southern side and the ammonoid community indicating the deeper neritic environments on the northern side.