喀喇昆仑断裂带磁组构特征及其构造意义  

Characteristics of magnetic fabrics of the Karakoram fault belt and its tectonic significance.

作　　者：周勇[1] 许荣华[1] 阎月华[1] 杨灿尧[2] 罗伟[3] 潘裕生[1] 

机构地区：[1]中国科学院地质与地球物理研究所,北京100029 [2]台湾大学地质系 [3]台湾中国文化大学地质系

出　　处：《岩石学报》2000年第1期134-144,共11页Acta Petrologica Sinica

基　　金：国家自然科学基金! (编号 :496 72 14 5和 4990 2 0 19);中国科学院青藏高原研究项目! ( KZ95 1-A1-2 0 4-0 1-0 5 ;KZ95 T-0 6 )

摘　　要：本文讨论了喀喇昆仑断裂带的磁组构特征。磁化率几何平均值随岩石所含矿物不同而有很大改变 ,校正磁各向异性度 PJ在变形强弱不同的岩石中有较大区别。大多数磁化率椭球体有良好的磁面理和最短轴方位 ,表现出强烈的压扁型应变型式 ;最短轴方位被视为最大主应力方向 ,在工作区呈 NE- SW向 ,并有低至中等大小的倾角 ,由于喀喇昆仑断裂走向 NNW-SSE,表明其走滑运动为右旋 ,在不同地区断裂两盘则有不同的垂向差异运动。同位素测年数据表明喀喇昆仑断裂的这次构造运动发生在中新世后期 ( 6 .88± 0 .36至 8.75± 0 .2 5 Ma)。This paper deals with the characteristics of magnetic fabrics of the Karakoram fault belt. The geometric mean values of the susceptibilities vary with minerals and their contents. Most of the susceptibility ellipsoids are strongly oblate with very accurately defined foliation planes and minimum axis orientations. The corrected anisotropy degree P J differs between the less and more deformed rocks. The minimum axis directions, which are assumed to reflect the directions of maximum principal stress direction, mostly trend NE SW. Considering the NNW SSE striking Karakoram fault, determination of the direction of movement is demonstrated. The overall movement is horizontally dextral and the west wall in localised units moves vertically upward or downward with respect to the east one. Isotopic dating shows that this movement occurred between 6.88±0.36 and 8.75±0.25Ma. This set of new quantitative analyses of anisotropy of magnetic susceptibility, together with the structural analysis, is in agreement with the geodynamic evolution of the Karakoram fault belt.

关 键 词：磁组构 喀喇昆仑 构造意义 岩石 断裂带 

分 类 号：P542.3[天文地球—构造地质学] P588.331[天文地球—地质学]