鄂尔多斯及其邻近块体相对运动的黄土古地磁证据  

PALEOMAGNETIC EVIDENCE FROM LOESS FOR THE RELATIVE MOTION BETWEEN THE ORDOS AND ITS ADJACENT BLOCKS

作　　者：李万伦[1] 卢演俦[1] 丁国瑜[2] 

机构地区：[1]中国地震局地质研究所,北京100029 [2]中国地震局分析预报中心,北京100036

出　　处：《第四纪研究》2001年第6期551-559,共9页Quaternary Sciences

基　　金：国家自然科学基金项目 (批准号 :4 9732 0 90和 4 9872 0 6 2 )资助

摘　　要：针对我国北方风积黄土广泛分布、不同地点黄土 -古土壤序列可准确对比和黄土沉积剩磁稳定等特征 ,通过对不同地壳块体上相同层位的黄土样品沉积剩磁方向的测定 ,进一步探讨了应用“虚磁极法”研究鄂尔多斯块体与相邻块体的相对运动的可能性。初步的研究结果显示 :该方法有可能应用于块体相对运动的定量研究 ,并初步得到 ,在第四纪时期鄂尔多斯块体相对于邻近块体作逆时针转动 ,自 2 .5MaB .P .以来相对秦岭块体的转动约为 3 1 .5°± 1 1 .4°,自 1 .1 7MaB .P .以来相对西宁块体的转动约为 2 9.8°± 1 4.7°,自 0 .46MaB .P .以来相对太行山块体的转动约为 8.2°± 5 .8°,相对于西宁块体的转动约为 1 0 .5°± 6 .4°。本文还根据这些块体间相对转动的角度初步估算了鄂尔多斯块体与相邻块体之间的活动断裂带不同时期的水平位移总量。Loess recorded stable detrimental remanent magnetization (DRM). It is possible to reveal the relative motion between the Ordos and its adjacent blocks by using the VGP (virtual geomagnetic pole) method in loess. Our preliminary results indicate that the Ordos block had rotated counterclockwise during the Quaternary period. Since 0.46MaB.P., its rotation relative to the Taihangshan block has been about 8.2°±5.8° and its rotation relative to the Xining block about 10.5°±6.4°. Its rotation relative to the Xining block has been about 29.8°±14.7° since 1 17MaB.P. and about 31.5°±11.4° relative to the Qinling block since 2.5MaB.P. From these results, the following estimates can be obtained: (1) there has been about 31.7km dextral slip along the western edge of the Ordos block (Liupanshan fault zone) since 1.17MaB.P.; (2) about 27.5km sinistral slip along the Weihe fault-bounded zone since the early Pleistocene (ca. 2.5MaB.P.); and (3) about 10.7km dextral slip along the Shanxi fault-bounded zone since 0.46MaB.P.

关 键 词：黄土 虚磁极法 鄂尔多斯块体 相对转动量 古地磁 沉积剩磁方向 

分 类 号：P542[天文地球—构造地质学] P642.131[天文地球—地质学]