【摘要】 以同位素组成地球化学资料为基础,结合岩性与电性特征,利用测井旋回分析技术,对四川盆地及周缘地区中上寒武统洗象池群进行地层层序划分并分析沉积特征与演化规律。洗象池群可以划分为Sq1—Sq5共5个三级层序,其中层序Sq1—Sq3保存相对较完整,层序Sq4与Sq5在寒武纪末期大面积剥蚀,展现出滇—川古隆起的特征。各三级层序均呈西薄东厚,显示出加里东古隆起是同沉积古隆起且台内古地貌为缓坡特征。层序Sq1同时发育高位体系域和海侵体系域,其他三级层序主要发育高位体系域,海侵体系域发育短暂且局限。洗象池群沉积期在台内以缓坡型蒸发—局限台地的基本面貌发育,西高东低的沉积环境与台内微古地貌变化控制着沉积相的持续发育,其中开阔台地只发育在层序Sq1和Sq2,台内滩与台缘滩在层序Sq2和Sq3最发育。洗象池群在四川盆地周缘地区存在相对稳定且规模较大的黔东北—湘鄂西台缘带和具有迁移性且规模较小的渝北—鄂西台缘带。更多还原

【Abstract】 Based on isotopic geochemistry data, lithologic and electrical characteristics and logging cycle analysis technique,stratigraphic sequences in Middle–Upper Cambrian Xixiangchi Group in Sichuan Basin and its adjacent area are divided, and its sedimentary characteristics and evolution are analyzed. The Xixiangchi Group can be divided into 5 third-order sequences(Sq1—Sq5), of which sequences I to III(Sq1—Sq3) are relatively complete, sequence IV and V are denuded at the end of Cambrian, having the characteristics of Dian-Chuan paleo-uplifts. Third-order sequences of the Xixiangchi Group in this area have the characteristics of thin in the west and thick in the east, showing that the Caledonian paleo-uplift is a synsedimentary paleo-uplift and the paleogeomorphology in the platform is a gentle slope. Sequence I developed high stand systems tract and transgressive systems tract, the other third-order sequences are dominated by highstand systems tracts, and the transgressive systems tracts are short in time and limited in area. The basic features of evaporation-confined platform of gentle slope type developed continuously in the sedimentary period of the Xixiangchi Group,its sedimentary environment of "west high and east low" and the change of micro paleogeomorphology in the platform control the continuous development of sedimentary facies. Open platform is developed only in sequence I and sequence II, and the inner beach of the platform and the edge beach of the platform are mostly developed in sequence II and sequence III. It is believed that there are two platform margin zones in the study area, a relatively stable, large-scale platform marginal zone of NE Guizhou–Western Hunan and Hubei,and a mobile, small-scale platform marginal zone of North Chongqing–Western Hubei.更多还原