Bohu Depression Structural Style And Tectonic Evolution

Bohu Depression is located in the southern part of the Yanqi Basin.The tectonic unitsinclude the southern depression,Zhongmachang salient and the northern depression. Thestudy area of Bohu Depression of Yanqi Basin is an area of5400km2. Bohu Depression is inthe conversion area of the basin-mountain coupling and has complex structuralcharacteristics. Different zones and the period of structural control factors are inconsistent.From the structural geology as a starting point, the paper discuss the structuralcharacteristics of Bohu Depression control hydrocarbon accumulation through thekinematics, geometry and dynamics.Yanqi Basin is between the three basins of the Tarim,Junggar and Turpan-Hami. Fromsouth to north it can be divided Bohu Depression, Yanqi uplift and Hejin Depression,reflecting the pattern for “two depressions and one uplift”. Basin within the broaderdistribution of formation bottom-up are as follows: lower Jurassic Badaowan formation,Sangonghe formation, the Middle Jurassic the Xishanyao formation and Cenozoic strata,the lack of a large area of the Upper Jurassic strata. Cretaceous strata of the region missing.Deposits are mainly alluvial fan, braided, braided river delta and lacustrine deposits,belonging to a conglomerate, mudstone, coal and carbonaceous mudstone interbeddedcontinental coal-bearing strata.Bohu Depression fault structure is very development. Ruptures of north of the West tothe North West are the main. North of the West to the breaking scale is the most oftenspaning the entire basin, while the plane was en echelon distribution of the majority. Faultnature is the thrust fault, and no normal fault development within the basin, the fault foldtectonic style main thrust imbricate, back thrust, hedge type is the flower.Balanced cross section technique is the forward-inversion method of geological profilefollowed the principle of geometric conservation and is an effective way of mensurableanalysis about the developing history of the structure.Combining with the regional tectonicsetting and basin sedimentary sequence evolution, Based on the method, we select restoredtrunk profiles of the Yanqi basin in Bohu depression, and analysis structural evolutioncharacteristics of the tectonic stages. The results show that Bohu depression experiencedearly Jurassic compressional basin, Middle-Late Jurassic stable subsidence stage, Cenozoicforeland basin three basin evolution stages.According to the structural evolution stages and the basin evolution features, by means of the agency about characteristics of resource-reservoir-cap rocks, combining with atectonic stage when the form of basin types and sedimentary environment, this paperanalyzes the tectonic style and tectonic evolution of oil and gas accumulation of controlfunction. And we point out exploration level, main construction zones and explorationtarget of Bohu Depression.