Palaeomagnetism and detrital zircon U–Pb geochronology of Cretaceous redbeds from central Tibet and tectonic implications
Palaeomagnetism and detrital zircon U–Pb geochronology of Cretaceous redbeds from central Tibet and tectonic implications
复制标题
西藏中部白垩纪红层的古地磁、碎屑锆石U-Pb年代学及其构造意义.
DOI：
10.1002/gj.3070
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发表时间：
2017
影响因子：
1.8
通讯作者：
Meng Wang
中科院分区：
文献类型：
--
作者：
Jun Meng;Xixi Zhao;Chengshan Wang;Hao Liu;Yalin Li;Zhongpen Han;Tao Liu;Meng Wang
要了解亚洲内部地壳缩短的幅度和拉萨-羌塘地体的碰撞年龄，需要对地壳运动进行定量约束。关键是确定青藏高原的古地理，这在整个汇聚史上是一个鲜为人知的因素。羌塘地体陆相阿不山组碎屑锆石U-Pb年代学和古地磁资料表明，藏中地区位于27.5°±33.0°N，时间间隔为~111~83 Ma。我们的结果表明，在印度-亚洲汇聚期间，羌塘中部与蒙古之间发生了7.5°±2.9°的大陆缩短。赤纬异常表明，中央羌塘地体相对于稳定的欧亚大陆经历了显著的顺时针旋转(57.3°±23.9°)。对白垩纪以来古地磁结果的整理表明，拉萨地体自123 Ma±9.9 Ma向北漂移约8.5°，至97°±17.7 Ma，拉萨地体与羌塘地体在约111~103 Ma之间存在古纬向重叠。结合陆源阿布山组的形成时代，我们的研究结果为班公中特提斯洋的闭合以及拉萨和羌塘地体的最终碰撞提供了最年轻的时间(约111-103万Ma)。
Understanding the magnitude of intra‐Asian crustal shortening and the collision age of Lhasa–Qiangtang terranes requires quantitative constraints on the crustal motion. The key to this is defining the palaeogeography of the Tibetan Plateau, which constitutes a poorly known factor over the entire convergence history. New detrital zircon U–Pb geochronological and palaeomagnetic data from the terrestrial Abushan Formation in the Qiangtang terrane demonstrate that central Tibet was located at 27.5 ± 3.0°N during the time interval of ~111–83 Ma. Our results suggest 7.5 ± 2.9° continental shortening has occurred between central Qiangtang and Mongolia during the India–Asia convergence. Declination anomaly indicates the central Qiangtang terrane has experienced significant clockwise rotation (57.3 ± 3.9°) relative to stable Eurasia. The compilation of palaeomagnetic results since the Cretaceous reveals ~8.5° northward drift of the Lhasa terrane from 123 ± 9 to 97 ± 7 Ma and the palaeolatitudinal overlap between the Lhasa and Qiangtang terranes after ~111–103 Ma. Together with the onset age of the terrestrial Abushan Formation, our results provide the youngest timing (ca.~111–103 Ma) for the closure of the Bangong Meso‐Tethys Ocean, as well as for the final collision of the Lhasa and Qiangtang terranes.