贝加尔裂谷和汾渭地堑成因与印度欧亚碰撞的远程效应

Genesis of the Baikal Rift and the Fenwei Graben and the remote effects of the Indo-Eurasian collision

位于欧亚板块东部的贝加尔裂谷和汾渭地堑是两个著名的裂谷系,它们具有相似的外形和地貌特征,也具有相似的地质构造演化历史。其成因机制长期以来一直存在争议,诸多研究说明它们的形成和印度与欧亚大陆碰撞密切相关,但印度与欧亚碰撞的远程效应是如何传递到这些区域的?本文通过大陆漂移过程中的陆缘区域的地幔上涌所形成的伸展构造演化和陆缘裂解,结合欧亚大陆新生代构造演化,研究印度欧亚碰撞的远程效应所导致的微陆块裂解漂移及伸展构造发展演化规律。结果说明这两个裂谷的成因与欧亚东缘新生代大规模微陆块裂解漂移密切相关。新生代伴随着青藏高原的隆升,欧亚大陆东缘发生了大规模地幔上涌和陆块裂解,日本、堪察加等陆块发生了裂解漂移,它们的裂解漂移在欧亚东缘形成了差异左旋走滑环境,从而分别在西伯利亚克拉通和鄂尔多斯克拉通东南侧形成了两个裂谷系和地震带,这两个地震带和2023年2月土耳其大地震具有类似的成因机制,它们都是走滑断裂所形成的地震带。用新大陆漂移模型可以合理解释其成因机制。

The Baikal Rift and the Fenwei Graben are two famous rift systems located in the eastern Eurasian plate,with similar topographic features and geomorphic characteristics.Their tectonic evolution histories are also similar.Many studies have shown that their formation is closely related to the Indo-Eurasian collision,however,the mechanism for this long-range effect is not clear.In this paper,basing on the evolution of extensional tectonics caused by mantle upwelling in the continental margin during the continental drift and continental margin splitting,combined with the Cenozoic tectonic evolution of Eurasia,we studied the evolution of microcontinental fragments and extensional tectonics under the long-range effect.The results show that the origin of the two rift systems is closely related to the Cenozoic large-scale fragmentation and drift of microcontinents in the eastern margin of the Eurasian.Briefly,the Qinghai Tibet Plateau uplift results in large-scale mantle upwelling and continental breakup in the Cenozoic,where the breakup and drift of the proto-Japan/proto-Kamchatka blocks form a differential sinistral strike-slip environment,and lead to the formation of the two rift systems in two seismic zones on the southeast side of the Siberian and Ordos Basins.These two seismic zones,which have similar genetic mechanisms to the Türkiye earthquake in February 2023,are formed by strike slip faults,and their genetic mechanisms can be reasonably explained by the new continent drift model.