广西贵港蒙公下泥盆统郁江组珊瑚层状礁特征

广西贵港蒙公下泥盆统郁江组珊瑚层状礁是广西早泥盆世塘丁期生物礁的代表。通过野外剖面的测制及详细的室内镜下薄片研究以及微量元素地球化学分析,认为该区发育由单个层状礁在垂向上反复出现形成较大规模的礁复合体。主要造礁生物为床板珊瑚、四射珊瑚,含量为70%～80%,附礁生物主要有单体珊瑚、腕足、腹足等。生物礁的生长发育与C、O同位素值呈现正相关关系。礁下部混积陆棚相泥岩是良好的烃源岩,导致了后期同层砂岩裂缝内烃类物质充注。

Characteristics of coral stratigraphic reef of Lower Devonian Yujiang Formation in the Menggong, Guigang, Guangxi

The coral stratigraphic reef of Yujiang Formation in the Menggong,Guigang is a typical case of stratigraphic reef which existed in Tangding stage,Early Devonian.After the field measuring of columnar section,detailed indoor study of thin sections and geochemical analysis of trace elements,it is recognized that there has developed a large-scaled-reef complex composed of repeatedly appearing stratigraphic reef horizons vertically in the direction.The main reef-building organisms are Favosites and Xystriphylloides in the content of 70%～80% in the reef.The main reef-dwelling organisms are individual corals,brachiopods and gastropods. The growth and development of the reef appears to be in a positive correlation with the shifting of carbon and oxygen isotopes. Mudstones of the hybrid shelf deposits below the reef are of good hydrocarbon source rocks,which caused later charge of hydrocarbon in fissures of contemporaneous sandstones.