塔里木陆块新元古代—早古生代古板块再造及漂移轨迹

Paleo-plate Reconstruction and Drift Path of Tarim Block from Neoproterozic to Early Palaeozoic

塔里木陆块周缘的新元古界地层记录了涉及Rodinia聚合和裂解的构造热事件,但塔里木在Rodinia超大陆中的位置以及在Rodinia裂解后如何运动尚无定论。采用收集的古地磁数据,并结合塔里木西北缘阿克苏地区的野外工作以及塔里木周缘代表性岩石如A型花岗岩、基性岩墙群、大陆溢流玄武岩和双峰式火山岩等的同位素年代学数据,将塔里木陆块从Rodinia超大陆中裂解的时间限制在830～700 Ma BP。之后,塔里木陆块随澳洲板块一起加入冈瓦纳大陆。约在450Ma BP,塔里木陆块和澳洲板块发生分离,并快速北漂,最终在晚古生代加入劳亚大陆。新元古代—早古生代,塔里木陆块整体上从北半球较高纬度向南半球漂移,并在奥陶纪向北半球快速回返。

The Neoproterozoic strata which mainly distributes in the periphery of the Tarim Block records lots of Tectono-thermal events related to the assembly and breakup of the Rodinia Supercontinent, yet the positon of the Tarim Block in Rodinia and how the Tarim Blcok moved after the breakup of Rodinia remains controversial. Based on the collection and selection of the published paleomagnetic data and the paleomagnetism method, we obtain the paleolatitude and drift path from Neoproterozoic to early Paleozoic of the Tarim Block. Moreover, combined with our field work and the isotope chronology data of representative rocks such as A type granite, mafic dyke swarms, conti- nental flood basalt and bimodal volcanic rocks in the Tarim＇ s periphery, we conclude that there was a strongly rif- ting event surrounding the Tarim Block during 830 - 700 Ma BP, which caused the Tarim Block breaking off the Ro- dinia Supercontinent. However, the separation was not complete, and the Tarim block joined the Gandwana Super- continent along with Australia. Through comparing the variation of the paleolatitude of the Tarim Block and the Aus- tralia Plate, we conclude that-their separation time was about 450 Ma BP. Then, the Tarim Block drifted towards north, and joined the Laurentia Supercontinent in late Paleozoic. During the Neoproterozoic to early Paleozoic, the Tarim block, on the whole, presented a drift parh from high north latitude to south latitude, and had a rapid return process to north latitude in the Ordovician.