下扬子地区中二叠世上升流相区古生态学研究

A Study on Palaeoecology in Upwelling Phase Region of Middle Permian in the Lower Yangtze Area

首次对下扬子地区中二叠世上升流相区古生态特征进行了研究。将栖霞组划分为5个沉积期,并划分了栖霞组各沉积期和茅口期的生物群落,其中本部灰岩段和顶部灰岩段沉积期群落分异较为明显,并阐述了各群落的组成、结构和生态环境。根据群落的组合特征和沉积学特征,在研究区识别出两种生物相类型,即陆棚缓坡底栖型生物相和陆棚盆地浮游型生物相,并论述了生物相与上升流强度之间的关系。最后,分析了上升流对生物古生态特征的控制作用,认为,上升流的发育强度和生物群落的丰度成正相关,而与分异度多成反相关。

The authors firstly make a study on Palaeoecology in upwelling phase region of Middle Permian in the Lower Yangtze area. The Qixia Formation is divided into five sedimentary ages, and the organic communities are recognized in this paper, at the same time, compositions, structures and ecologic environments are also discussed. Based on the analysis of characters of community association and deposition, two kinds of biofacies are recognized, namely benthonic biofacies of shelf glacis and planktonic biofacies of shelf basin, the relationship between biofacies and intensity of upwelling current is elucidated in the paper. Finally, the analysis of the control of upwelling current on paleoecologic features demonstrates that the intensity of upwelling current corresponds to abundance of organic community and discords from diversity.