鄂西新滩二叠纪腕足类的群落演变与环境关系

系统研究了湖北省西部新滩剖面亚丁斯克阶至长兴阶的腕足动物群落演替过程。通过研究区与华南地区及特提斯区域进行比对分析，结合前人对碳、氧同位素的研究结果，分析了二叠纪腕足类群落演替的规律和区域差异。结果表明:除二叠纪末的灭绝事件，在乌拉尔统与瓜德鲁普统界限附近及乐平统中共识别出两次腕足类种群的显著分异度变化，且其演替时间都接近6~8个百万年。前一次体现在冷水种与暖水种的混合过渡现象，后一次体现在个体增大、壳饰发育与个体变小、壳体变薄的不同分化现象。在气候方面，冰期与季风的强弱作为主要因素从温度及养分来源共同影响腕足类的多样性变化。火山喷发事件及板块运动改变腕足类生态环境并造成区域的分化。海平面变化既受气候影响也受地壳运动影响，高频的海平面变化不断改变着腕足类在研究区的生存空间。腕足类在适应不同环境中所发生的壳体形态改变、群落结构演替很好的展示了生物环境对古环境的响应。

Permian Brachiopods in Xintan,Western Hubei:Community evolution model and response to environmental changes

A systematic study of the succession process of the brachiopod community from Artinskian to Changhsingian at Xintan， western Hubei Province is described. The causes and regional differences within the Permian brachiopod community succession were analyzed by comparative analysis of the study area， South China area and Tethys area， combined with previously reported carbon and oxygen isotope values. Except for the extinction events at the end of the Permian， two significant changes were identified in brachiopod populations near the Cisuralian/Guadalupian and Guadalupian/Lopingian epoch boundaries in the Permian about 6?8 million years apart. The first change was evident in the mixed transitions of cold-water and warm-water species， and the latter is seen in various differentiation phenomena （individual enlargement， development of shell ornamentation and individual shrinkage， and shell thinning）. The strengths of the ice age and monsoons were the main climatic factors， when temperature and nutrient sources jointly affected brachiopod diversity. Volcanism and plate movements changed the brachiopods’ ecological environment and caused regional differentiation. Sea-level changes were affected both by climate and crustal movement. In the study area， highly frequent sea-level changes constantly altered the living space of the brachiopods. The changes in shell shape and community structure succession of brachiopods were adaptations to different environments， showing the response of the biological environment to the paleoenvironment.