塔里木盆地古董山地区早二叠世古地磁特征及其地质意义  

New Permian paleomagnetic data from Gudong Mountain area in the Tarim Block and their tectonic implications

作　　者：许伟[1] 孙知明[2] 李海兵[3] 裴军令[2] 潘家伟[3] 司家亮[3] 赵越[2] 任晓娟[2] 

机构地区：[1]中国地质调查局西安地质调查中心,陕西西安710054 [2]中国地质科学院地质力学研究所国土资源部古地磁与古构造重点实验室,北京100081 [3]中国地质科学院地质研究所大陆动力学国家重点实验室,北京100037

出　　处：《地质通报》2013年第10期1566-1574,共9页Geological Bulletin of China

基　　金：中国石油化工集团公司项目(编号:YPH08110);中国地质调查局项目(编号:1212010918036)

摘　　要：通过对塔里木盆地内古董山地区早二叠世玄武岩的古地磁测定,揭示了1组高温特征剩磁分量。实验结果表明,其特征剩磁方向为:Dg=213.7°,Ig=26.9°,κg=19.7,N=9,α95=13.7°;Ds=217.7°,Is=-37.5°,κs=15.4,α95=13.6°,相对应的古地磁极位置为:53.2°N、187.5°E,A95=12.3°,古纬度为21.0°N。由于采样剖面所获得的早二叠世古地磁结果全部为反极性特征,认为这一高温特征剩磁分量很可能代表了研究区早二叠世时期的原生特征剩磁。对比塔里木地块西北缘早二叠世的古地磁结果,认为研究地区与塔里木地块西北缘之间在古地磁误差范围内并未发生明显的相对构造运动。依据塔里木早二叠世古地磁极与哈萨克斯坦地块同时期古地磁极的一致性,结合二者的古生物资料,提出早二叠世时期塔里木地块可能已经与哈萨克斯坦地块碰撞相连,至晚二叠世,二者之间的海水完全退出,碰撞造山使得天山雏形基本形成。结合前人古地磁研究成果,对塔里木地块及周边主要块体早二叠世的古地理进行了重建。Paleomagnetic determinations of the Early Permian basalt rocks in the Gudong Mountain area of Tarim block （38.74N/ 79.7E） are presented in this paper. Stepwise thermal demagnetization successfully revealed stable characteristic residual magnetization （ChRM）. Generally, reversal polarities were observed in all sampled sites in the studied section. The tilt-corrected mean directions of the Early Permian are D/I=217.7/-37.5 with oL95 being 13.6 and N being 9, corresponding to a paleopole at 53.2N, 187.5E, Ags=12.3. Compared with the Early Permian poles from the northwestern margin of the Tarim block, the authors hold that in- significant tectonic movement may have occurred between the interior of Tarim and its northwestern margin within paleomagnetic uncertainties. Based on the Early Permian paleopole from the Kazakhstan block and paleontological information, the authors consid- ered that the two blocks may have collided and experienced collage in the early Cretaceous. The sea between the Tarim block and the Kazakhstan block had not vanished until the Late Permian. In association with previous studies, the authors carried out EarlyPermian paleogeographic reconstruction which included China＇s major blocks.

关 键 词：早二叠世 塔里木 古地磁 古地理重建 

分 类 号：P534.46[天文地球—古生物学与地层学] P539.3[天文地球—地质学]