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柴达木北缘地区前陆盆地背靠相对活动的南祁连造山带，面朝相对稳定的柴达木微板块，在中生代（至少侏罗纪）曾历经强烈的挤压作用，形成了一系列与褶皱—冲断作用有关的构造样式。该前陆盆地在平面上呈狭长状，沿南祁连山前绵延分布。根据地震剖面解释及地质资料综合分析表明，柴北缘侏罗纪沉积盆地具较典型的前陆盆地剖面形态，且该前陆盆地呈现背驮式渐次向前（盆内）发展演化模式。柴北缘地区逆冲推覆构造及其前陆盆地起始于印支运动，形成于燕山运动，改造于喜马拉雅期。柴北缘前陆盆地由南祁连造山带往盆内，可以划分为：南祁连造山带、柴北缘逆冲叠瓦扇带、隐伏逆冲前缘带及前缘斜坡带四个构造单元。在柴北缘前陆盆地中，最有利于油气富集的构造部位为柴北缘逆冲叠瓦扇带至隐伏逆冲前缘带

Evolution of the Foreland Basin and the Target for Oil and Gas Exploration in the Northern Margin Area of Chaidamu Basin

The foreland basin in the northern margin area of Chaidamu Basin backs on to the relatively active southern Qilianshan orogenic belt and faces the relatevely stable chaidamu microplate.In the Mesozoic (at least in the Jurassic),it has undergone an intense compressional effect,forming a series of the structural types related to foldingthrust effect.Horizontally,this foreland basin is a long and narrow zone,distributing along southern Qilianshan piedmont.According to the seismic profile interpretation and the synthetic analysis of the geological date,it is shown that the Jurassic sedimentary basin in Chaidamu's northern margin has a relatively typical foreland basin section form and the foreland basin assumes a backshaped and gradually forwardevolutionary pattern (in basin).The thrust nappe structure and its foreland basin in Chaidamu's northern margin area started in the Indosinian movement age,formed in the Yanshan orogeny age and reformed in the Himalayan age.From southern Qilianshan zone to the basin's inside,the foreland basin in Chaidamu's northern margin can be divided into four structural units,i.e. southern Qilianshan orogenic belt,thrust imbricated fan belt in Chaidamu's northern margin,hidden thrust frontal belt and frontal clinoform zone.The structural location which is most beneficial to oil and gas accumulation is from the thrust imbricated fan belt to the hidden thrust frontal belt in Chaidamu's northern margin.