Structural Characteristics And Hydrocarbon Prospects Of Kalpin Thrust Belt In The Northwestern Tarim Basin

Kalpin thrust belt,a duplex thrust structure,is located in the northwestern margin of the Tarim Basin,and its degree of exploration is lower,so it is of great significance for revealing the oil and gas under the ground.In this paper,tectonic deformation characteristics and evolution of the Kalpin thrust belt will be studied.Based on the theory of fault-related folds,through geological exploration to study the characteristics of the formation outcrop and structural deformation,we draw a comprehensive stratigraphic column of the study area;through analysis of surface geological section and seismic geological section,the fracture characteristics,the deformation characteristics and genetic mechanism of structure of the Kalpin thrust belt will be revealed;by apatite fission track analysis experiments of the field samples to study the thermal chronology Kalpin thrust belt low,analyze its uplift time;with 2Dmove software to make balanced section,we research the evolution of structure formation process.In the end,through analyzing the conditions of petroleum geological,the oil and gas prospects is predicted in the region.Kalpin thrust belt,a convex curved southward thrust structures,with westward plunge and eastward Yingan fault,has the regional tectonic characteristics of zoning from east to west,division from south to north,layering from upper and lower.On the plane,Kalpin thrust belt,having 4-6 fold-thrusts from north to south,is divided into east and west partitions by Piqiang fault,the western part of Kalpin thrust belt(Sickl area)and Kalpin eastern thrust belt.On the profile,the features of Kalpin thrust belt is a dual structure:the shallow structural features are imbricated thrust combination based,the fault goes slowly down steep plow north eventually slip into middle Cambrian Ava-tage group,the deeper structure is a detachment structure,bottom boundary is bedrock detachment surface,the upper and lower structural layers are superimposed on each other and stacked relationship.Piqiang,Saergan and other fracture are able to adjust the intensity of tectonic deformation,displacement rate,and the size of the converter fault displacement.Kalpin thrust belt evolution experienced four major stages:(1)Late Caledonian-early Hercynian(460-299Ma),the ancient southern Tianshan Ocean closed from east to west like a scissors,forming residual Southern Tianshan Ocean,at this time Kalpin was at active continental margin;(2)Late Hercynian(270-250Ma),Tarim plate collision with the Yili together,leading to the close of the residual South Tianshan Oeean and slipping along the Calbrian layer of gypsum rock southward thrust in Kalpin area;(3)early Indosinian-Yanshan period(250-65Ma),Kalpin thrust system was stable,and truncated the top;(4)Himalayan period(23Ma-now),due to the collision between India plate and Eurasian plate continued northward push effect,especially the Pamir micro block in north west wedging has influence on central Asia and Kalpin area,and south Tianshan orogeny is active again,large-scale push from north to south and the interaction of oblique rotation from west to east.Kalpin thrust is to the south and east over-thrust again,resulting in Paleozoic strata from west to east,north to south under cover overlying the Pleistocene Xiyu group(Q1x),while basement tectonic activity,resulting in a wedge south of imbricate structure,tectonic deformation of the superficial transformation,Kalpin over-thrust structure systems also tend to form basic.Kalpin thrust belt is one of the areas of Tarim Basin that marine source rock outcrops are well-developed.Oil and gas may accumulate in Salam Braque anticline,underground concealed structure zone and Hala Jun basin,especially Hala Jun basin and buried structure,which may be the preferred target for future oil and gas exploration in the area.