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南华裂谷盆地在南华纪出现地垒区与地堑区的明显沉积分异。在对黔东松桃地区将军山剖面南华系地层进行实测的基础上,与地堑区南华系地层进行了对比。发现地垒区与地堑区的沉积分异主要表现在铁丝坳组与大塘坡组的岩性与厚度变化上。在此基础之上,对将军山剖面大塘坡组底部凝灰层进行LA-ICP-MS锆石U-Pb年代学研究,得到年龄值为664.2±2.4 Ma。通过该年龄与前人在地堑区所获得的对应地层年龄进行对比,可将南华裂谷盆地地垒区Sturtian冰期结束时间限定在不晚于663~667 Ma范围内,这证明Sturtian冰期消退事件在黔东地区范围内具有等时性,整个Sturtian—Marinoan间冰期持续时间约为10 Ma。与此同时,通过与世界范围内各古板块上Sturtian冰后期沉积的最新定年结果进行对比工作,得出全球Sturtian冰期结束时间同样具有等时性的结论。
Significant Sedimentation Differentiation Between South China Rift Basin and South China Sea in the Basement and Graben Areas. On the basis of measuring the Nanhua System strata of the Songshan section in Songtao, Qiandong, it is compared with the South China System stratigraphy in the graben area. It is found that the sedimentary differentiation between the base and graben areas is mainly manifested in the changes of lithology and thickness of Tiexiao Formation and Datangpo Formation. On this basis, LA-ICP-MS zircon U-Pb geochronology of the tuff layer at the bottom of Datangpo Formation in JJ section was studied, and the age value was 664.2 ± 2.4 Ma. By comparing this age with the corresponding stratigraphic age obtained in the graben area, the end of the Sturtian glacial period in the basement of the South China Rift Basin can be limited to no later than 663-667 Ma, which proves that the Sturtian glacial regression It is isochronous within the area of eastern Guizhou and the duration of the interglacial Sturtian-Marinoan glaciation is about 10 Ma. At the same time, by comparing with the latest annual results of late Sturtian ice deposits on various ancient plates in the world, it is concluded that the end of the Sturtian ice age in the world is equally time-laden.