Permian age of the Wudaogou Group in eastern Yanbian: detrital zircon U-Pb constraints on the closure of the Palaeo-Asian Ocean in Northeast China
Permian age of the Wudaogou Group in eastern Yanbian: detrital zircon U-Pb constraints on the closure of the Palaeo-Asian Ocean in Northeast China
复制标题
延边东部五道沟群二叠纪时代：碎屑锆石U-Pb对中国东北古亚洲洋闭合的制约
DOI：
10.1080/00206814.2014.956348
复制
发表时间：
2014-10-26
影响因子：
2.6
通讯作者：
Hu, Zhao-Chu
中科院分区：
文献类型：
--
作者：
Chen, Cong;Ren, Yun-Sheng;Hu, Zhao-Chu
五道沟群对索隆克-西拉木伦河-长春缝合带的形成时间和向东终止起着重要的制约作用，古亚洲洋在这里闭合。五道沟群由片岩、片麻岩、角闪岩、变质沉积岩和变质火山岩组成，均经历了绿片岩-绿帘石-角闪岩相区域变质作用，其中一些角岩是接触变质作用的产物。为了确定五道沟群的沉积时代、变质作用时间和变质程度以及构造环境，我们对该群变质岩进行了岩相学和年代学研究。变质沉积岩中的锆石可分为岩浆成因的变质锆石和碎屑锆石。变质锆石的LA-ICP-MS U-Pb年龄为249 +/-4~266 +/-4Ma，与延边东部区域变质作用的年龄相近。碎屑锆石U-Pb年龄为253 +/-5~818 +/-5Ma，表明五道沟群的物源在818~253Ma经历了4次构造-热事件：新元古代（约100Ma）、晚元古代（约100Ma）和晚元古代（约100Ma）。818 - 580Ma），寒武-奥陶纪（ca. 500 - 489Ma），泥盆纪-石炭纪（约. 422 - 300Ma），以及中晚二叠世（约。269 - 253Ma）。最年轻的碎屑锆石U-Pb年龄为253 ± 5Ma，确定了五道沟群的最大沉积年龄。寒武-奥陶纪和新元古代碎屑锆石的出现，表明五道沟群的物源与中国东北地区有密切关系，由此推断Solonker-Xra Moron河-长春缝合带从延边东部汪清延伸至珲春，古亚洲洋可能在二叠纪末或早三叠世闭合。
The Wudaogou Group in eastern Yanbian, Northeast China, plays a key role in constraining the timing and eastward termination of the Solonker-Xra Moron River-Changchun Suture, where the Palaeo-Asian Ocean closed. The Wudaogou Group consists of schist, gneiss, amphibolite, metasedimentary, and metavolcanic rocks, all of which underwent greenschist- to epidote-amphibolite-facies regional metamorphism, with some hornfels resulting from contact metamorphism. To determine the age of deposition, the timing and grade of metamorphism, and the tectonic setting of the Wudaogou Group, we investigated the petrography and geochronology of the metamorphic rocks in this group. Zircons from the metasedimentary rocks of this group can be divided into metamorphic zircons and detrital zircons of magmatic origin. U-Pb ages of metamorphic zircons dated by LA-ICP-MS vary from 249 +/- 4 to 266 +/- 4Ma, approximating the age of regional metamorphism in the eastern Yanbian area. Detrital zircons yield U-Pb ages ranging from 253 +/- 5 to 818 +/- 5Ma, and indicate that the provenance of the Wudaogou Group experienced four tectonic-thermal events between 818 and 253Ma: Neoproterozoic (ca. 818-580Ma), Cambro-Ordovician (ca. 500-489Ma), Devonian-Carboniferous (ca. 422-300Ma), and middle-late Permian (ca. 269-253Ma). The youngest detrital zircon, with a U-Pb age of 253 +/- 5Ma, defines the maximum depositional age of the Wudaogou Group. The presence of the Cambro-Ordovician and Neoproterozoic detrital zircons implies that the source of the Wudaogou Group had an affinity with Northeast China, which leads us to conclude that the Solonker-Xra Moron River-Changchun Suture extends from Wangqing to Hunchun in eastern Yanbian, and that the Palaeo-Asian Ocean may have closed at the end of the Permian or Early Triassic period.