粤西德庆地区晚奥陶世化石的发现及其地质意义

DISCOVERY OF THE LATE ORDOVICIAN FOSSILS IN DEQING,WESTERN GUANGDONG AND ITS GEOLOGICAL SIGNIFICANCE

本文介绍了广东西部德庆地区近年来新发现的一个晚奥陶世动物群,包括化石产出层位、生物组合类群及其科学意义。该动物群产自原划分为中奥陶世东冲组的地层内,化石产出层位岩性为泥质粉砂岩,动物类群以三叶虫为主,伴生有腕足动物、棘皮动物及少量短剑类化石,化石保存多较破碎,仅少部分保存较好,分布非常集中,结合野外露头与沉积相特征,其沉积环境为正常浪基面至风暴浪基面间的高能滨浅海环境。该动物群的发现,不仅厘定了这套地层时代,而且丰富了粤西地区晚奥陶世的生物组合面貌,为该地区奥陶系的划分对比和区域地质演化研究提供了新资料。

This paper reports a newly discovered Late Ordovician fauna in Deqing, western Guangdong. The argillaceous siltstone yielding the fauna was previously assigned to the Middle Ordovician Dongchong Formation, but is here redefined to the Late Ordovician Lanweng Formation. The fauna consists mainly of trilobites, accompanied by brachiopods, echinoderms and machaeridians. The fossils are only founded in certain layers and are mostly fragmental. Fossil preservation and sedimentary features suggest a high-energy sedimentary environment ranging from the fairweather wave-base to the storm wave-base. The discovery of this fauna not only provided new information for the stratigraphic subdivision and correaltion, but also enriched the Late Ordovician biodiversity in the area.