柴达木盆地西部新生界磁组构特征及其构造意义  

MAGNETIC FABRICS OF CENOZOIC SEDIMENTARY ROCKS IN THE WESTERN QAIDAM BASIN AND THEIR STRUCTURAL SIGNIFICANCE

作　　者：李丽[1] 蒋荣宝[1] 祁万修 吴益平 杨屹 李学智 陈正乐[1] 陈宣华[1] 王小凤[1] 任小娟[1] 

机构地区：[1]中国地质科学院地质力学研究所,北京100081 [2]新疆地质调查院第一地质调查所,乌鲁木齐830011

出　　处：《地质力学学报》2008年第1期45-56,共12页Journal of Geomechanics

基　　金：国家重点基础研究发展计划资助项目(2007CB411305);国家油气专项柴达木盆地油气资源战略调查及评价项目(XQ-2004-01)

摘　　要：柴达木盆地西部狮子沟一带新生代沉积岩磁组构分析结果显示,岩石磁组构具有磁面理发育、磁线理不发育、磁化率量值椭球呈压扁状的特点;磁化率各向异性度P值不大,反映总体构造变形相对较弱。岩石磁组构反映的应力状态总体为以NE向挤压为主,与轴向NW的背斜构造发育相一致。该区岩石磁组构大多具有原始沉积磁组构特征,磁面理产状大体上反映沉积岩层的层理,同时也记录了受NE向挤压作用的痕迹。根据岩石磁组构与地层层理之间的关系分析,柴西地区两翼不对称的狮子沟背斜具有断展褶皱性质,其形成与下部的花土沟逆冲断层向南西方向的仰冲有关。Magnetic fabric analysis of Cenozoic sedimentary rocks in the vicinity of Shizigou, western Qaidam basin, shows that the magnetic fabrics are characterized by well-developed magnetic foliation, undeveloped magnetic lineation and a flattened magnetic susceptibility ellipsoid, and the P value symbolizing the degree of magnetic susceptibility anisotropy is low, suggesting that ductile deformation is relatively weak. The stress state reflected by the rock magnetic fabric is mainly manifested by NE compression, which is consistent with the arrangement of the anticlines with axes running NW. The magnetic fabrics in the area mostly have the features of primary sedimentary fabrics, with the magnetic foliations largely reflecting the bedding of sedimentary rocks and also recording the signs of NE compression. According to the relation between the magnetic fabrics of rocks and bedding of strata, the Shizigou anticline with two asymmetric limbs in the western Qaidam basin has the nature of a fault- propagation fold and its formation was due to the southwestward obduction of the Huatugou fault underneath.

关 键 词：柴达木盆地西部 新生界 磁组构 构造变形 

分 类 号：P138.4[天文地球—天体力学]