新疆三塘湖盆地晚古生代基底结构和变形特征

Late Paleozoic Basement Structures and Deformational Characteristics of Santanghu Basin in Xinjiang Region

三塘湖盆地是一个有含油气远景的盆地,但对盆地的基底的研究始终没有一个统一的认识。通过对盆地周缘地层、构造的变化研究,结合重磁资料及钻井资料,认为该盆地的基底是早古生代西伯利亚南缘活动陆缘沟-弧-盆沉积体系经变质褶皱作用而形成的,主要经历了两个阶段,即中泥盆世-晚泥盆世早期洋壳俯冲阶段和晚泥盆世-早石炭世残留海盆阶段。研究表明,三塘湖盆地的重力基底和电性基底有明显的不一致性,其重力基底为侏罗系的底界,而电性基底才反映了真正的盆地构造基底。基底变形以叠瓦式逆冲构造为主要特征。主要经历了海西末期的冲断褶皱阶段和燕山期的逆冲推覆阶段。

Santanghu Basin was a prospective area with hydrocarbon potential,but study on the basement was not unanimously recognized.Based on the stratigraphic and structural studies from the peripheral formation of the basin and in combination with the gravity,magnetic and drilling data,it was considered that its basement was originated from the metamorphism and folding of the arc-trench system in the southern active continental margin of the extended Siberian Block,it experienced two tectonic evolutional stages,that was the Middle-late Devonian subduction and the Late-early carboniferous remnant ocean.The investigations show that there exists obvious inconsistency between the gravity-defined basement,which represents the basal boundary of the Jurassic System,and conductivity-defined basement,which is the actual basement of the sedimentary basin characterized by the imbricate thrusts.The Santanghu Basin has experienced two deformational stages,such as the thrust-fold deformation at the end of the Hercynian and the thrust-nappe deformation during the Yanshanian.