Paleomagnetic and Chronologic Data Bearing on the Permian/Triassic Boundary Position of Qamdo in the Eastern Qiantang Terrane: Implications for the Closure of the Paleo-Tethys
Paleomagnetic and Chronologic Data Bearing on the Permian/Triassic Boundary Position of Qamdo in the Eastern Qiantang Terrane: Implications for the Closure of the Paleo-Tethys
复制标题
钱塘地体东部昌都二叠系/三叠系边界位置的古地磁和年代学资料：对古特提斯洋闭合的启示
DOI：
10.1029/2020gl092059
复制
发表时间：
2021-03-28
影响因子：
5.2
通讯作者：
Shen, Miaomiao
中科院分区：
文献类型：
--
作者：
Guan, Chong;Yan, Maodu;Shen, Miaomiao
三江源区东部古特提斯构造演化至今仍不确定，特别是东羌塘地体（EQT）东部缺乏高质量的古地磁资料。本文对四川盆地尕底考组（Fm.）EQT中的火山岩这一先前假定的石炭纪或二叠纪岩石单元现在是锆石U-Pb，其年龄与254-248 Ma相似。我们新的高质量（29个站点和257个样本）推断的原始古地磁结果产生了一个强大的二叠纪-三叠纪边界古磁极59.7度N和228.2度E（A（95）= 3.3度），与古纬度10.0 +/- 3.3度N的研究区域。结合EQT和塔里木地块二叠-三叠纪的古地磁资料及其他地质证据，我们认为EQT在300-200 Ma期间持续向北漂移，昌都地区古特提斯洋可能在232-220 Ma左右闭合，最可能在230 Ma左右。
The tectonic evolution of the eastern Paleo-Tethys in the Three-Rivers headwater region remains uncertain, especially because of the lack of quality paleomagnetic data from the east Eastern Qiangtang Terrane (EQT). Here, we present an integrated paleomagnetic and zircon U-Pb geochronologic study of the Gadikao Formation (Fm.) volcanic rocks in the EQT. This previously assumed Carboniferous or Permian rock unit is now zircon U-Pb dated to similar to 254-248 Ma. Our new high quality (29 sites and 257 samples) inferred primary paleomagnetic results yield a robust Permo-Triassic boundary paleopole of 59.7 degrees N and 228.2 degrees E (A(95) = 3.3 degrees), with a paleolatitude of 10.0 +/- 3.3 degrees N for the study area. Integrated with other reliable Permo-Triassic paleomagnetic data of the EQT and the Tarim Block and other lines of geologic evidence, we propose that the EQT drifted continuously northward during 300-200 Ma and the Paleo-Tethys Ocean probably closed at similar to 232-220 Ma around the Qamdo region, most likely at 230 Ma.