新疆乌孙山北缘断裂晚第四纪活动及区域构造意义

乌孙山北缘断裂位于新疆伊宁盆地南部，是伊宁盆地与乌孙山的边界断裂，由多条平行或斜列的次级断层组成.断裂呈近东西走向，总体倾向南，山前主断裂主要表现为高角度逆冲，倾角50°~80°，前缘冲断面相对较缓.断裂上盘主要由石炭系-二叠系组成，下盘主要为第四系和侏罗系，断层两盘沉积物的ESR年代表明断裂带多处错断中、上更新统地层.野外地层接触关系和区域构造研究表明，在中更新世末以来，断裂强烈向北逆冲，与伊犁盆地北缘断裂共同控制了盆山地貌格局.伊宁盆地及邻区中更新世末的区域构造运动与青藏高原的共和运动时代相当，这次事件由南北天山向伊犁盆地的对冲挤压引起，动力来源于青藏高原向外扩展生长. 

Constraints on Late Quaternary Activity of North Wusunshan Fault in Xinjiang and Its Regional Tectonic Implications

North Wusunshan fault zone lies on southern margin of Yining basin, Xinjiang, which is a boundary fault between Yining basin and Wusunshan. The fault zone is composed of a suit of secondary parallel or en echelon faults. The faults strike in east-west direction, and dip to the south generally, the main fault next to Wusunshan is characterized by steep reverse fault plane with dip angle of 50°-80°, the frontal fault close to Yining basin shows gentler fault plane. The Carboniferous and Permian strata consist of hanging wall, and the Quaternary and Jurassic strata make up the footwall. ESR dating of sediments for hanging wall and footwall indicates that the Mid-Upper Pleistocene is truncated by the faults in specific places. Based on stratigraphic contact and regional tectonic analysis, North Wusunshan faults thrust intensively toward the north during the latest Mid-Pleistocene, in the meanwhile, North Yining faults thrust intensively toward the south, and the two groups of fault belts control basin-mountain geomorphic framework. This tectonic event is equivalent with the Gonghe Movement in the Tibet plateau, which is attributed to compression from the North and South Tianshan, which thrust toward Yili basin, regional tectonic mechanism stemmed from outward growth and expansion of the Tibetan plateau.