Abstract: An important phase of tectonic events took place in the Qiangtang Basin, northern Xizang during the Late Mesozoic, and led to the termination of marine deposition and the formation of regional unconformity in the basin. However, there has long been much debated concerning the ages of the tectonic event and its bearings on the hydrocarbon accumulation and preservation in the basin. The authors in this study contend, in terms of the preexisting data such as stratigraphic age, sediment burial history and hydrocarbon accumulation, that this tectonic event was initiated between the Early and Late Cretaceous (ca. 100 Ma), and represented a tectonic response to the final collapse of the Bangong Lake-Nujiang Ocean basin and the collision of the Lhasa and Qiangtang blocks. The age of this tectonic event was contemporaneous with that of the hydrocarbon generation in the basin. The trap structures associated with this tectonic event are interpreted to be ideal localities, and thus are promising targets for the oil and gas exploration and assessment in the Qiangtang Basin.