新疆博格达山北缘大龙口地区构造特征与油气勘探前景

大龙口地区位于新疆博格达山与准噶尔盆地的结合部位，属于博格达山北缘山前冲断带的组成部分，关于该区地下地质构造特征，长期以来缺乏清楚的认识。通过地表地质、地震和非地震资料的综合研究，纵向上以阜康逆冲断裂为界，将该区划分为下盘伸展构造系统和上盘逆冲推覆构造系统，前者为原地系统，构造变形较弱，保留有早二叠世裂谷的隆坳结构，对重新认识博格达山地区早二叠世的区域大地构造背景及演化具有重要意义；后者构造变形强烈，总体以自南向北的冲断推覆为主，并伴有一定的走滑扭动变形。经过多期构造运动，阜康断裂上盘勘探目的层已裸露，加之褶皱和断裂发育，油气保存条件差，勘探前景较差；而断裂下盘发育早二叠世残留凹陷，圈闭发育，油气保存条件好，勘探前景较好。

Structural Features and Petroleum Exploration Prospective in Dalongkou Area of the Northern Bogda Mountain,Xinjiang

Dalongkou area, located between Bogda Mountain and the eastern Junggar Basin, Xinjiang, is an integral part of the northern fold and thrust belt of Bogda Mountain.Many studies have been carried out about the surface structural features in recent years, but the underground structural features are not clear till now due to the complexstructural deformation and poor seismic imaging quality making identification of underground structures difficult. By surface geology, seismic and magnetotelluric dataintegrated research, given Fukang thrust fault works as a detachment, two structural systems can be divided vertically which are the extensional tectonic system of the Early Permian rift in the lower part and the fold and thrust system in the upper part. The former belongs to the in situ system with weak structural deformation, and the juxtaposedtectonic framework of the Lower Permian faulted high with fault depression is clear which is of great importance in rethinking regional tectonic setting and evolution of BogdaMountain in the Early Permian; the latter, with intense structural deformation, is characterized by the thrusting from south to north, and accompanied by some strike-slipdeformation. Undergoing multiple-stage tectonic movements, the Permian to Jurassic exploratory objectives are exposed, together with the intense deformation of folds andfaults, and the preservation becomes poor, herein makes petroleum exploration prospects poor. On the other hand, there exist favorable petroleum elements, and given theexistence of an Early Permian “residual fault depression”, a greater exploration potential for oil and gas can be assumed in the footwall of the Fukang thrust fault.