山东车镇凹陷东部古近系沙河街组成岩作用

DIAGENESIS OF SHAHEJIE FORMATION OF THE PALAEOGENE IN THE EASTERN CHEZHEN DEPRESSION OF SHANDONG PROVINCE

车镇凹陷沙河街组的沉积体系受控于盆地内的构造、物源供给以及沉积时的气候环境。以岩石学特征为基础 ,描述了成岩过程中压实与压溶作用、胶结作用、溶解作用与次生孔隙的特征 ,以及次生孔隙带在本区的分布。论述了碳酸盐胶结物与粘土矿物胶结作用的特点。粘土矿物蒙脱石—伊利石转变具有明显的渐变与突变交替的演化程式 ,其演化经历了蒙脱石带、渐变带、迅速转化带和伊利石带以及蒙脱石向伊利石的转变带。沙河街组的成岩作用划分为早期成岩阶段 (A期、B期 )和晚期成岩阶段 (A期、B期、C期 ) 。

The sedimentary system,tectonic features, lithological features and diagenesis of Palaeogene of Shahejie Formation in the eastern Chezhen Depression of Shandong Province are studied in detail. The characteristics of compaction and solution, cementation, secondary porosity during diagenesis processes and the distribution of secondary porosity zone in Chezhen Depression are described. The features of the cementation of carbonate cements and clay minerals indicate that the transition of the clay minerals from montmorillonite to illite has evolutionary pattern of obvious gradation and mutation, and that the evolutionary processes experienced montmorillonite zone, gradation zone, rapid transition zone and illite zone. According to the relation of transition from montmorillonite to illite, the diagenesis of Shahejie Formation is divided into the early diagenetic stage (stage A, stage B), and the late diagenetic stage(stage A, stage B, stage C). The dividing indexes of the diagenetic stages are proposed.