湘黔渝毗邻区南华纪岩相古地理及沉积盆地演化

湘黔渝毗邻区大地构造位置位于扬子陆块东南缘,发育有完整的南华纪沉积记录,同时也是我国南华纪“大塘坡式”沉积型锰矿的重要富集区。通过对区内南华系剖面的详细调查与研究,结合室内综合分析,应用“优势相”成图方法编制了南华纪早世、中世、晚世岩相古地理图件。研究表明:受Rodinia超大陆全球性裂解作用影响,南华纪时期扬子陆块东南缘发生广泛的裂解作用,形成武陵次级裂谷盆地和雪峰次级裂谷盆地,构成“堑-垒”式古地理格局,南华系是在这一背景下形成的“楔状”沉积体;划分出大陆相组、过渡相组和海相组三大沉积相组,识别出河流相、湖泊相、三角洲相、海岸相以及浅海陆棚相等沉积相及若干沉积亚相等。系列图件的编制恢复了南华纪时期的沉积盆地演化与古地理变迁,建立了沉积盆地演化模式,为区域上沉积型锰矿的预测与寻找提供了一定的沉积学依据。

Lithofacies Palaeogeography and Sedimentary Evolution of Hunan–Guizhou–Chongqing Border Area in the Nanhua Period

Located on the southeastern margin of Yangtze block,the study area has preserved a complete depositional record of Nanhua Period.The“Datanpo type”manganese deposit in this area is an important manganese resource base.In this paper,based on an investigation of the formation system of Nanhua Period,the authors found that,under the background of Rodinia supercontinent breakup,the southeastern margin of Yangtze block experienced intensive regional extensional rifting and formed The Nanhua rift consisting of Wuling and Xuefeng secondary rift basins.Through the study of sedimentary structure and the rock slice identification for the Nanhua period sections,sedimentary facies belts were identified.They included continental,transgressive and shallow marine facies.The results obtained by the authors have deepened the understanding of the Nanhua period,and provide important information for geological prospecting in the study area.