Analysis Of The Characteristics Of Palaotectonic Stress In Area Of Wuling Mount

After many years of oil-gas exploration and research in South China,we have reached a consensus that it is one of the most important questions that the influence of the massive structure and evolution of the Middle-Upper Yangtze Plate on preservation conditions fro oil and gas reservoirs of the Paleozoic erathem.Multistage folding and lifting movements happened there and the evolution was very complicated.There were many different tectonic tracks which had different directions and mechanical property.Moreover,because the property of the tectonic movement and the characteristics of paleo-tectonic stress(direction and magnitude)were different,there was very controversial about the process of forming and developing of the tectonic tracks.This article focuses on conjugated shear joint and striation and regional structural setting in the Wuling Mount area,based on field survey and previous data.In last,we gained 3 issues of the meso-Cenozoic tectonic stress field and analyzed regional characteristics of tectonic field evolution and dynamic mechanism.The main stages of the tectonic stress field were Indosinian Stage,early Yanshan Stage and late Yanshan-early Himalayan Stage.The directions were nearly S-N,E-W and NWW-SEE in sequence.There were mainly tectonic extrusion.Based on the analyses of regional geological background and conjugated joint inversion,we performed numerical simulations in the Wulingshan region during the late Yanshan-early Himalayan Period and then compared the results and the geologic structural phenomena.The results shows that the high value area of the maximum principal stress distributes between Sinan-Yinjiang fault zone and Cili-Baojing fault zone and in the middle of Qiyue Mount fault zone;the low value area of the minimum principal stress distributes in the fault turning area;the shear stress zone distributes in the fault,the variation positon of attitude of faults,at the intersection position of two sets of faults;there are some positive values in the northeast Qiyue Mount fault and the southwest Sinan-Yinjiang fault zone,which shows there is in the shear stress state,other region are negative value,which shows there is in the extrusion stress state;displacement of east-west geomorphological boundary is largest,which is 3.39 *10-8m,while displacement of south-north geomorphological boundary is medium and displacement of central zone is smallest,which closes to zero.