关键词: 构造特征, 伸展构造, 逆冲推覆构造, 油气前景, 大龙口地区, 博格达山北缘, 新疆

Abstract:

 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 complex  structural deformation and poor seismic imaging quality making identification of underground structures difficult. By surface geology, seismic and magnetotelluric data  integrated 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 juxtaposed  tectonic 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 Bogda Mountain in the Early Permian; the latter, with intense structural deformation, is characterized by the thrusting from south to north, and accompanied by some strike-slip  deformation. Undergoing multiple-stage tectonic movements, the Permian to Jurassic exploratory objectives are exposed, together with the intense deformation of folds and  faults, and the preservation becomes poor, herein makes petroleum exploration prospects poor. On the other hand, there exist favorable petroleum elements, and given the existence 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.

Key words: structural feature, extensional structure, thrust and nappe structure, petroleum exploration prospective, Dalongkou area, the northern Bogda Mountain, Xinjiang