平邑盆地下第三系官中段核形石成因分析

平邑盆地下第三系官中段核形石较为发育，类型多样。通过对其内部结构的研究发现核形石单元纹层有六种类型，作为核心的藻类仅在顶端发生碎屑粘结效应，而其底部则发育厚度小，规则的暗色纹层。纹层组合类型多样，主要受藻类发育程度，水动力强度和藻类种属的控制，是不同水动力环境下的产物。根据颗粒大小、纹层组合类型纹层层数、填隙物将核形石分为浅水高能成因核形石和较深水低能成因核形石。核形石成因分析和分类对沉积环境的判

The oncoids genesis in the Middle Member of the Guanzhuang Formation of Eocene in Pingyi Basin

Many types of oncoids are well developed in the Middle Member of the Guanzhuang Formation of Eocene in Pingyi Basin. By the research of the internal structure, six types of the fundamental lamina are classified, which are controlled mostly by the developed degree of the algae, water dynamics and species of algae. The different lamina grouping types reflect sedimentary environment. It is discovered that the algal core coherents detritus only on the top and the bottom of the core forms regular thin melalamina. Consequently, two genetic types of the oncoids (shallow water-high energy and deep water-low energy oncoids) are classified according to the grain size, the types of the lamina groups, the amount of the lamina and the filling material. The genetic analysis and classification of the oncoids are helpful for the indication of the sedimentary environment.