扬子地块西部下奥陶统碎屑锆石LA-ICP-MS U-Pb年代学及其地质意义

发布时间：2019-08-07 17:54

【摘要】：华南地块在冈瓦纳大陆中的位置长期以来存在较大的争议,为了探讨华南地块早古生代期间的古地理位置,本文采用U-Pb同位素测年技术对扬子地块西部云南地区下奥陶世统红石崖组沉积岩开展了碎屑锆石原位LA-ICP-MS U-Pb年代学的研究。碎屑锆石U-Pb年龄谱特征表明,所采样品U-Pb年龄数据存在5个显著的年龄峰值,分别为524Ma、590Ma、830Ma、977Ma和2480Ma。本次研究获得了大量的泛非期锆石,反映出华南与冈瓦纳大陆之间的亲缘性。研究区与印度北部特提斯喜马拉雅、羌塘、澳大利亚西部及滇缅泰马地块具有相似的碎屑锆石年龄特征,表明这些地块的碎屑物质源区极为相似,华南与这些地块可能相邻或相距并不遥远。本文研究结果与前人根据其他地质资料得出的华南在早奥陶世期间位于澳大利亚的西北部,与滇缅泰马地块相邻这一认识相吻合。
[Abstract]:The position of South China block in Gondane continent has been controversial for a long time. In order to explore the paleogeographic location of South China block during the early Paleozoic, U-Pb isotopic dating technique was used to study the sedimentary rocks of Lower Ordovician Hongshiya formation in western Yangtze block. The in situ LA-ICP-MS U-Pb chronology of clastic zircon was studied in this paper. The U-Pb age spectrum characteristics of clastic zircon show that there are five significant age peaks in the U-Pb age data of the samples, which are 524Ma, 590Ma, 830Ma, 977Ma and 2480Ma, respectively. In this study, a large number of pan-African zircon have been obtained, reflecting the affinity between South China and Gondane continent. The study area has similar age characteristics of clastic zircon with the Tethys Himalayas, Qiangtang, western Australia and Tamar blocks in northern India, indicating that the clastic material source areas of these blocks are very similar, and South China may be adjacent to or not far away from these blocks. The results of this study are in good agreement with the previous understanding that South China was located in the northwest of Australia during the early Ordovician period and adjacent to the Tamar block in Yunnan, Myanmar and Myanmar.
【作者单位】：中国地质科学院地质力学研究所;首都师范大学资源环境与旅游学院;中国地质调查局发展研究中心;
【基金】：国家自然科学基金项目(编号:41230208) 中央高校基本科研业务费专项资金资助(编号:310827171122) 中国地质科学院基本科研业务费项目(编号:YYWF201613)
【分类号】：P534.42;P597.3

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