贵州及邻区宝塔期岩相古地理研究

A Research on the Baota Age Lithofacies and Paleogeography in Guizhou and Its Adjacent Areas

贵州及邻区的奥陶纪地层分布广泛,发育较全,而中奥陶世宝塔期地层主要是一套灰岩相沉积。前人对这套地层的沉积特征做过概略的、小范围的研究,本文在此基础上,根据野外近五十条剖面的资料,系统地,以现代沉积学的理论和方法,进一步对贵州及邻区宝塔期沉积相进行研究并编制岩相古地理图。

Though predecessors made researches on the Baota age strata in Middle Ordovician in Guizhou and its adjacent areas, fewer researches were made on lithofacies and pale-ogeography. This paper deals mainly with the features of the sedimentary rocks and the types of rock associations by means of the new view, point and methods of modern sedimentology. On this basis, the paper divides the facies zones according to field observations, differentiation of facies marks and horizontal comparison, induction of the areas, reconstructing the horizontal distribution and the vertical evolution of the Baota age sedimentary, environment and working out the lithofacies and paleogeographic map of the Baota age. The sedimentation in the Baota age in Guizhou and its adjacent areas mainly consists of carbonate rocks, with rock types comparatively fewer. According to hydro-power, grain content and the kinds of biological pieces and the content of glued matter, the sedimentation can be divided into eleven rock types. These rocks can make up seven rock association forms vertically. According to hydro -power, grain content and the kinds of biological pieces and the content of glued matter, the sedimentation can be cevided into eleven rock types. These rocks can make up seven rock association forms vertically. According to the rock types, association forms, space occurrance state and biological group features, the sedimentation inlthe Baota age can be divided into seven facie' zones, and the corresponding sedimentary environment can be divided into ( 1 ) tida! alkalized lagoons south of Jinyang-Yiliang-Zhenxiong, ( 2 ) carbonate platform environment in northern Guizhou and southern Sichuan, ( 3 ) carbonate platform margin environment in eastern Guizhou, northeastern Guizhou and southern Guizhou and (4) land margin slide environment in southeastern Guizhou and southwestern Hunan.