柴达木盆地西部阿尔金斜坡地区盆山演化与油气勘探

通过高分辨、高精度古地磁测年剖面和地震生长层序分析,柴达木盆地西部阿尔金斜坡地区新生代以来至少发生了10次构造运动、3期构造幕,反映了阿尔金地区经历了3次加速隆升的过程。该区整体具准前陆特征,下第三系以逆冲作用为主,沉积、沉降中心相对稳定,是柴西主要烃源岩发育区;上第三系以走滑挠曲为主,沉积、沉降中心沿阿尔金断裂带由西南向东北明显迁移。垂直阿尔金造山带向盆内区可划分为山前高断鼻带、中部低断鼻带、盆内下第三系冲断前锋和反冲带。柴西阿尔金斜坡地区现今构造圈闭是多期冲断、走滑、掀斜隆升叠加作用的结果,发育构造圈闭、地层不整合圈闭、岩性圈闭,具有一定的油气勘探潜力。

Basin-range Evolution and Oil-Gas Exploration in Altun Slope Area of Western Qaidam Basin

According to the high-resolution and high-accuracy analysis on the paleomagnetic dating for profile and the seismic growth sequence, it is believed that at least 10 stages of structural movement and three structural episodics have occurred in the Altun slope area of western Qaidam Basin since the Cenozoic era, indicating that the Altun area has undergone three accelerate-uplift stages. In general, this area has foreland characteristics. The Paleogene is the main developed area of hydrocarbon source rocks in western Qaidam Basin, of which thrusting is the main structural feature and the sedimentary and subsidence centers are relatively stable. Strike-slip flexuring is the main structural feature of the Neogene and its depositional and subsidence centers obviously migrate from southwest to northeast along Altun fault. The vertical basin-oriented Altun Orogenic belt can be divided into the high fault-nose belt in the front of mountain area, the low fault-nose belt in the middle part, the leading thrusting belt and the recoiling belt in the Paleogene of Qaidam Basin. It is the superimposition of multistage thrusting, strike-slip, and tilting uplift that formed the current structural traps in the Altun slope area of western Qaidam Basin. The well-developed structural traps, unconformity traps, and lithological traps are the main structural trap types in this region and they have certain potential for oil and gas exploration.