川黔湘交境寒武纪层序划分

SEQUENCE DIVISION OF CAMBRIAN SYSTEM OF THE BOUNDARY AREA AMONG SICHUAN,GUIZHOU AND HUNAN PROVINCES

根据层序地层学的基本原理和概念，以露头剖面研究为基础将川黔湘交境寒武系（至奥陶系底）划分为１６个三级层序，其中下统含７个中统３个，上统（跨入奥陶系底）６个，既有Ⅰ型层序又有Ⅱ型层序，具倾斜边缘的盆地中形成的Ⅰ型层序仅发育在早寒武世早期，共２个；具台缘斜坡的盆地中形成的Ⅰ型层序发育在台地形成及发展阶段，即早寒武世后期至晚寒武世早中期，共５个。上述层序的详细研究为海平面升降和加里东早期的构造运动的认识提供了新的基础。

According to the basic principles and concepts of sequence stratigraphy and based on the researchs of outcrop profile, Cambrian System in the juncture of Sichuan, Guizhou and Hunan can be divided into sixteen third-grade sequences of which seven in the Lower Series, three in the Middle Seriesand six in the Upper Series (striding into the bottom of Ordovician System),including both I-type sequence and Ⅱ-type one.Total two Ⅰ-type sequences formed in the inclining margin basin are devel oped only in early Early Cambrian, while total five Ⅰ-type sequences formed in shelf break basin with platform margin slope develop in the formation and development stage of the platform, that is,fromlate Early Cambrian to early-middle Late Cambrian. The detailed researchs of above sequences provide anew foundation to understand eustacy and early Caledonian orogeny.