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首次获得黔桂地区晚前寒武纪四堡群凝灰岩(斑脱岩)锆石SHRIMP U-Pb年龄,结合新获得的侵位于四堡群的花岗岩锆石SHRIMP U-Pb年龄,将四堡群明确定位于新元古界。“江南造山带”普遍发育的新元古代四堡群(梵净山群、冷家溪群、双桥山群)和上覆的丹州群(下江群、板溪群、河上镇群)均为低变质绿片岩系,构成了江南古陆的变质基底。多年来四堡群一直划归中元古界,并且构成“四堡运动”的主体,其时代的定位一直影响着整个江南古陆变质基底的地层划分和对比,也制约着中国地质学家对江南造山带的地质背景和成矿条件解疑。通过对四堡群及其上覆地层中斑脱岩锆石的研究,精确地测定并获得了四堡群斑脱岩锆石的年龄841.7Ma±5.9Ma和黔东南摩天岭地区侵入四堡群的花岗岩锆石的年龄826.8Ma±5.9Ma。
The zircon SHRIMP U-Pb ages of the tuff (bentonites) of the Early Cambrian Silibu group in the Qianui-Guixi area were obtained for the first time. Based on the SHRIMP U-Pb ages of newly acquired granite intrusions in the Sibao Group, Clearly located in the Neoproterozoic. The “Neo-Proterozoic Si Bao Group (Fanjingshan Group, Lengjiali Group and Shuangqiao Group) and the overlying Danzhou Group (Xiajiang Group, Banxi Group, He Shangzhen Group) are low-metamorphic greenschist rocks, forming the metamorphic basement of the southern Yangtze River. Over the years, the Four Forts have been assigned to the Paleoproterozoic and constitute the main body of the ”Fort of Four Forts". The positioning of the times has always affected the stratigraphic division and contrast of the metamorphic basement of the ancient Jiangnan paleosol and also restricted the development of China’s geology DISCUSSION ON GEOLOGICAL BACKGROUND AND METALLOGENIC CONDITION OF THE JIANGNAN OROGENIC BELT. Based on the study of the bentonites in the Si Baoqun and its overlying strata, the age of 841.7Ma ± 5.9Ma and the intrusive SiBaoShan group in the Motianling area of southeastern Guizhou have been accurately determined. The age of granite zircon is 826.8Ma ± 5.9Ma.