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.%羌塘盆地在中生代晚期发生一次重要的构造运动,导致盆地结束海相沉积历史并形成区域性不整合.对该期构造事件发生的时代以及其对盆地油气成藏与保存的影响一直存在争议.本文根据近年来对羌塘盆地地层时代的新认识,结合盆地沉积埋藏和油气生成过程分析,认为该构造事件主要发生于早-晚白垩世之间(～ l00Ma),为班公湖-怒江洋盆最终闭合和拉萨-羌塘地块碰撞的结果.构造事件与盆地主要烃源岩该的生烃同时,盆地内与构造事件有关的圈闭构造为油气成藏提供了良好的场所,是盆地的主要评价和勘探目标.
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