华南晋宁期造山运动──地质年代学和地球化学制约

综合了前人和作者最新的地质年代学和地球化学研究成果，对华南晚元古代晋宁期造山运动的演化提供了化学地球动力学制约晚元古代早期（0．97－1．0Ga）的皖南、赣东北和桂北蛇绿岩在元素地球化学上具有相似的岛弧特征，但它们的Nd同位素组成明显不同新获得的高精度结石U－Ph年龄资料表明，桂北地区的本洞、三防和元宝山等三个主要花岗岩岩体均形成于820-825Ma，排除了本区有中元古代晚期花岗岩的存在．扬子南缘中元古代到三叠纪各个时代地层中的泥质沉积岩的TDM在晚元古代早期从约1．8Ga急剧降低至约1．3Ga，反映了这个时期的沉积物源区有大量新生馒源物质的加入．根据研究资料，提出了华南和扬子块体晋宁期陆-弧-陆碰撞模式

THE JINNING OROGENY IN SOUTHEAST CHINA:GEOCHRONOLOGICAL AND GEOCHEMICAL CONSTRAINTS

This paper synthesizes the geochronological and geochemical data from literature and my newly obtained, and places constraints on the geodynamic evolution for Jinning Orogeny in Southeast China. The early Neoproterozoic ophiolites from South Anhui, Northeast Jiangxi and North Guangxi are similar to each other in terms of geochemical features, with volcanics from them showing arc-signatures. However, they differ significantly from each other in their initial Nd isotopic compositions. The high-precision U-Pb zircon ages for three granitic plutons （the Bendong, Sangfang and Yuanbaoshan） from North Guangxi cluster around 820-825 Ma, excluding the existence of the late Mesoproterozoic granites in the region. A coherent secular variation of Nd model ages （TDM） is defined in fine-grained elastic sediments from the southern margin of the Yangtze block. In the middle Neoproterozoic and early Sinian （900-770Ma）, there is a dramatic decrease in Tab ages from - 1.8Ga to - 1.3 Ga,indicating a large increase in the proportion of juvenile mantle-derived materials from the provenance. A tectonic medel involving Proterozic continent-arcs-continent colliion between the Yangtze and Huanan blocks is proposed to be consistent with these observations.