库车坳陷晚白垩世隆升过程及其地质响应

Late Cretaceous uplifting process and its geological response in Kuqa Depression

利用裂变径迹分析技术 ,并结合地质学研究方法 ,对库车坳陷晚白垩世隆升过程进行了研究。库车坳陷晚白垩世隆升约发生在 89Ma前 ,平均隆升速率为 3 7 8～ 45 3m/Ma ,是一个较缓慢的隆升过程。这一隆升过程不仅造成了库车坳陷全区缺失晚白垩世地层 ,而且也导致了库车坳陷构造变形雏形的发育。晚白垩世的隆升事件局限在库车坳陷内部 ,没有影响到天山造山带。隆升事件的北部界限位于库车坳陷的前陆逆冲断层带中 ,界线南北的隆升差异明显 ,南部的隆升发生在晚白垩世时期 ,而北部的隆升事件发生在中新世时期。这一隆升过程在特提斯北缘的盆地群中都有表现 ,而隆升的形成是青藏高原地区Kohistan_Dras岛弧与拉萨地体在晚白垩世时期的碰撞事件远距离效应的结果。

The Late-Cretaceous uplifting process of the Kuqa Depression was investigated using the fission track (FT) technique and the geological analysis.The uplifting has occurred for about 89 million years.The average velocity of uplifting is from 37.8 to 45.3 meters per million years,which belongs to a slow uplifting process.This uplifting not only resulted in the erosion or non-deposition of the Late Cretaceous strata,but also in the formation of the structural rudiment of deformation in the Kuqa Depression.The uplifting of the Late Cretaceous was limited in the area of the Kuqa Depression and had no effect on the Tianshan orogenic belt.The northern boundary of uplifting event is located in the foreland thrust belt of the Kuqa Depression.The uplifting event in the north of boundary occurred in Miocene,and that in the south of boundary occurred in Late Cretaceous.This uplifting event is related to the collision between the Kohistan-Dras island arc and the Lasa Block in Late Cretaceous.It was the result of a long-distance effect of this collision.These results are very important to reveal the relationship between the Kuqa Depression and the Tianshan orogenic belt,and those also benefit to study the formation and evolution of oil and gas in the Kuqa Depression.