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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。
In order to explore the Paleozoic paleogeographic location during the Paleozoic South China block, the location of the South China block in the Gondwanaland has long been a controversial issue. The in-situ LA-ICP-MS U-Pb chronology of detrital zircons was studied in the sedimentary rocks of the Taoshi Red-Cliff. Detrital zircon U-Pb age spectrum characteristics show that there are five significant age peaks in U-Pb age samples, which are 524Ma, 590Ma, 830Ma, 977Ma and 2480Ma, respectively. The study obtained a large number of Pan-African zircons, reflecting the affinity between South China and the Gondwanaland. The study area has similar detrital zircon age characteristics to the Tethyan Himalayas, Qiangtang, Western Australia and Burma-Taima plots in northern India, indicating that the detrital material source areas are very similar in these plots, May be adjacent or not far apart. The findings of this paper are in line with our understanding of the fact that South China, based on previous geological data, was located in the northwestern part of Australia during the Early Ordovician, adjacent to the Taima block in Yunnan and Burma.