东昆仑地区沙松乌拉组物质来源及源区构造-热事件——来自碎屑锆石U-Pb年代学的证据

    The provenance of Salawula Formation in East Kunlun and the tectonic thermal events of provenance: The evidence from U-Pb chronology of detrital zircons

    • 摘要: 沙松乌拉组出露于东昆中构造混杂岩带,是东昆仑地区原特提斯洋洋盆打开时的沉积记录,确定其地层形成时代、物质来源及恢复构造演化过程,对研究东昆仑地区原特提斯洋的演化具有重要意义。对出露于东昆仑黑海湖—拉宁灶火沟一带的沙松乌拉组进行LA-ICP-MS碎屑锆石U-Pb年定,得到最年轻的锆石年龄为632±6 Ma,结合地层接触关系,为沙松乌拉组的时代划分提供了年龄依据;得到约650 Ma、约800 Ma、980 Ma三个明显峰值及大量未形成明显峰值的其他古老年龄,推测沙松乌拉组的主要物源有小庙群、万保沟群、晋宁期岩浆岩,次要物源为白沙河组。将得到的锆石年龄与各期构造-岩浆活动比对,认为沙松乌拉组的源区经历了古元古代早期构造-岩浆事件、中元古代晚期构造-岩浆事件和新元古代早期构造-岩浆事件。

       

      Abstract: Salawula Formation is the earliest marine deposit of East Kunlun in early Paleozoic.It's meaningful to reconstruct the tectonic evolution of east Kunlun in Early Paleozoic by studying Salawula Formation's formation time and its provenance.The authors obtained the youngest zircon age of 632±6 Ma by LA-ICP-MS U-Pb dating of the detrital zircons from Salawula Formation's clastic rocks and constrained its formation time.Moreover, there are three age ranges of ~650 Ma, ~800 Ma and ~980 Ma existent in the detrital zircons, and the authors infer that Baishahe Group, Xiaomiao Group, Wanbaogou Group and magmatic rocks formed during early Neoproterpzoic were Salawula Formation's provenance because of their similar zircon age distributions.Furthermore, the authors hold that the source areas experienced Early Paleoproterozoic, Late Paleoproterozoic, Late Mesoproterpzoic and Early Neoproterpzoic tectono-magmatic events according to the characteristics of their zircons' U-Pb age.

       

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