| Turpan-Hami Basin is located in the east of Xinjiang,tectonic units in the southeastern of Kazakhstan-Junggar plate,which is located in the flatten parts of Siberia.The basin which has experienced several tectonic evolution and polycyclic settlement is a superposed-extruded type sedimentary basin which contains coal,oil,natural gas.With the exploration degree in Turpan-Hami Basin continues to improve,it is very important to study deep structure and stratigraphic development in Turpan-Hami Basin.In this paper,the distribution characteristics of Carboniferous-Permian stratum are studied and analyzed by using the collected the gravity and magnetic data and the previous research results,the geophysical basis for further oil and gas exploration in Turpan-Hami basin is provided.In this paper,using the collected the gravity and magnetic data in Turpan-Hami Basin,through moving average,regularized filter,analytical continuation,horizontal first derivative of each direction,the vertical second derivative,the total horizontal gradient processed the gravity and magnetic data,combined with seismic,drilling data and petroleum geology achievements in the study area,systematically analyzed the characteristics and causes of gravity and magnetic anomaly in this region,speculated the fault structures in the study area,discussed the distribution characteristics of Carboniferous-Permian stratum,divided the tectonic units,predicted the favorable area of oil and gas.The paper has the following main results and conclusions:(1)The Bouguer gravity in Turpan-Hami Basin is "high low high" phase distribution from south to north.The high and low gravity in the area reflects the tectonic pattern of basement uplift and depression.Most of the low gravity is caused by the thicker Cenozoic-Mesozoic,and the high gravity is caused by the uplift of the high density basement.(2)Fault development and complex structure in Turpan-Hami Basin.The main faults are east-west and north-west trending,the secondary faults are north-west and north-east trending.The main faults with large scale and long distance,which reflected the regional structure in the study area,controlled the development of the stratum in the study area.Secondary faults are mainly developed in sedimentary caprock,they are small in scale and short in extension distance,and generally cut off main faults.(3)The stratum of the Cenozoic,Mesozoic and upper Palaeozoic in Turpan-Hami Basin are widely developed,and the depth of the basement interface is quite different.There are two subsidence centers in the basin,namely the Turpan depression and the Hami depression.In Turpan depression,the thickness of the Cenozoic is relatively thin,and the thickness of Mesozoic and Upper Paleozoic is relatively large.The structure of Hami depression is complex,and the Cenozoic deposits are thinner,the thickness of Mesozoic and upper Palaeozoic is quite different,and some parts of Mesozoic are missing.(4)The Turpan-Hami Basin can be divided into three first-order tectonic units,including the Turpan depression,Liaodun uplift and Hami depression.The Turpan depression can be further divided into the Taipei depression,Toksun depression and Aidinghu slope 3 secondary tectonic units.The Hami depression can be further divided into 2 secondary tectonic units,the Sanbao depression and the Nanhu structural belt.Research shows that sedimentary formations is thick in Taibei depression,Toksun depression and Sanbao depression,which has a good source-reservoir-seal assemblage,and it is the favorable exploration area of oil and gas. |
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