山东省平邑盆地古近系湖相核形石特征及环境意义

山东省平邑盆地古近系官庄组湖相核形石较富集，其特征和分布受古沉积环境的控制。在总结前人研究的基础上，运用野外现场观测、偏光显微镜和扫描电镜观察、地球化学测试等技术手段，研究了本区核形石灰岩的岩石形态、结构、古生物、构造、元素地球化学等具有环境指示意义的特征，并据此将该区核形石分成A、B两类，它们之间根本性区别在于其形成的沉积环境的不同，A类核形石形成于翻转、滚动的强水动力的，水体较浅且较混浊的滨湖岸滩-浅湖浅滩环境；而B类核形石形成于水体较深、较平静的且较清澈的浅湖湖湾环境。研究结果表明，本区的核形石发育于一个处于湖侵体系域阶段的干热湖盆的缓坡地带。

Characteristics and Environmental Significance of Lacustrine Oncolites in Paleogene Guanzhuang Formation in Pingyi Basin, Shandong Province in Eastern China

Many types of oncoids, which have great significance for sedimentary environment research, are well developed in Paleogene Guanzhuang Formation in Pingyi Basin. Based on previous studies, the morphometry, structure, fossil, texture and the characteristics of geochemistry of the oncolites in host area were analyzed by means of field inspection, microscope observation and geochemical test. In order to study the characteristics and environmental significance of lacustrine oncolites in Paleogene Guanzhuang Formation in Pingyi Basin, the following aspects are described in this paper:
  (1) The general geological conditions of the host area.
  (2) The research on the sedimentary environment and growing pattern of the oncoids in host area in Guanzhuang Formation.
  (3) The characteristics of the oncoids and oncolites in host area.
  (4) The classification the oncoids in Paleogene Guanzhuang Formation in Pingyi Basin.
  Based this study, the oncoids were divided into Type A and Type B, and the most fundamental difference between them lies in sedimentary environments where they originated. Type A originated in the higher energy water than Type B, and Type A developed in quiet and clean water while Type B growed in the turbid water. According to above study, the oncolites developed in a close, dry and hot lake, which was on the stage of transgression. 