中国南方青白口系的厘定

ON THE STIPULATION OF THE QINGBAIKOU SYSTEM IN THE SOUTH CHINA

中国南方是否存在青白口系,以及如何划分、对比,是长期争论的重要地质问题。作者遵循构造岩浆旋回划分前寒武系的基本原则,根据区域不整合面、沉积建造,结合同位素地质年龄、微古植物组合,以扬子地区为重点,进行分析研究,提出中国南方青白口系的底界为晋宁运动造成的不整合面,顶界在与莲沱组底界或与莲沱组相当层位的底界交界处,同位素地质年龄分别为10±、8±亿年。文中并分区叙述青白口系的地层特征。

There has been a long debate upon the important question whether the Qingbaikou System developed in South China and how its division and correlation can be made . In accordance with the principles of tectonomagmatic cycles, the Precambrian Systems mainly in Yangtze region are divided, studied and analysed in the paper, on the basis of the regional unconformity, sedimentary formation and correlation combined with the data of iso-topic age and micropaleobotany assemblage. The author proposes a scheme for the division and correlation of the Qingbaikou System in South China. Its bottom boundary is an unconformity resulted from the Jinning Movement, and its top boundary is at the bottom boundary of Liantuo Formation or the bottom boundary of equivalent horizons to Liahtuo Formation, with the isotopic ages being 100±Ma and 80±Ma, respectively. The strati-graphic characteristics of the system are discussed for each subarea.