摘要
湖南栖霞期发育了 8种不同类型的生物群落 ,各自反映了不同的沉积环境。这些生物群落的时空分布规律反映了当时的古地理概貌。根据群落分布及岩性特征可将栖霞期的湖南浅海划分为 5个古地理单元。在涟 (源 )浏 (阳 )开阔浅海的部分海底隆起区 ,由Per onidella群落形成了生物礁。这是国内首次发现的栖霞期生物礁。
Various fossil communities in different places indicated a shallow marine with various depositional environments developed in Hunan during the Qixia Period of Middle Permian. The Stigmaria and Skolithos communities indicated the environments of seamarsh (or littoral depression) and supratidal respectively. The Pycnostroma community meant a very shallow turbulent environment, including the intertidal zone and very shallow subtidal zone. The Orthotetina community was characteristic of the nearshore subtidal environment with soft mud substratum. The Lophophyllidium community occupied the underturbulent subtidal environment, suffered occasionally by storm turbulence; and the Wentzellophyllum community showed the clear subturbulent subtidal environment, where compound rugose corals were broken and overthrown frequently by storms. The trace fossil Zoophycos community developed in a stagnant anaerobic area of restricted shallow marine. The Peronidella community lived in a clear and relatively turbulent subtidal environment, where was very suitable for flourishing of benthic organisms. In the Sangzhi Shimen, Chenxi Huaihua and Dongkou Xinhua areas, the Stigmaria community developed well at the beginning of Qixia Period, indicating environments of seamarsh or littoral depression. Then the Orthotetina and Zoophycos communites dominated, meaning a relatively restricted sea near the oldland. In Lianyuan Liuyang, the Wentzellophyllum community occurred widely, comprehending an open shallow sea. The Skolithos and Pecnostroma communities at the beginning of Qixia Period proved a wide tidalflat zone or very shallow subtidal zone. In Shaoyang Leiyang, the Skolithos and Pecnostroma communities never found, the Lophophyllidium and Zoopycos communites supported an evidence of the area far away from the oldland and the environments being more restricted. Based on distributions of the various communities, five paleogeographic units could be divided in Qixia Period: the Sangzhi Shimen littoral shallow sea, Chenxi Huaihua littoral shallow sea, Dongkou Xinhua littoral shallow sea, Lianyuan Liuyang open shallow sea and Shaoyang Leiyang restrict shallow sea. The reefs of Qixia Period, composed of the sponges of Pronidella community and firstly discovered from Shuangshouting to Xiandong of Lianyuan, Central Hunan, was located on the margin of the Lianyuan Liuyang open shallow sea.
出处
《地质科学》
CAS
CSCD
北大核心
2003年第2期190-199,共10页
Chinese Journal of Geology(Scientia Geologica Sinica)
