湖北宜昌王家湾五峰组顶部Chondrites的发现及其环境意义

本文报道了湖北宜昌王家湾剖面五峰组笔石页岩段观音桥层发现的遗迹化石Chondrites的分布及其生态特点。结合生物相和同期上扬子海盆相对海平面的变化，分析了盆地水体底域在缺氧一富氧转折时期的古氧相变化特征：指出五峰组笔石页岩段上部地层沉积底域为典型的缺氧环境，在其与上覆观音桥段之间的沉积转换面附近发生了从无氧到有氧的转变，观音桥段中Hirnantia动物群繁盛于富氧的海底环境。

Discovery of Chondrites in uppermost Wufeng Formation, in Wangjiawan Section, Yichang, Hubei, and its Environment Signification

The trace fossil Chondrites is discovered in the boundary interval between the black graptolite shale and Guanyinqiao Members of the Wufeng Formation in the Wangjiawan section, Yichang area, Hubei, China. Based on analysis of the paleoecological characters and related bifacies with the change of sea level of the Yangzte basin in the corresponding period, it is suggested that the fluctuations in the degree of palaeo - oxygenation of the bottom waters. Result from this paper is that the uppermost part of black shale of Wufeng Formation represented a typical oxygen - deficient environment, whereas the Himantia fauna flourished in acrobic enviroment, and between them, the Chondrites fauna indicated a obvious transition from oxygen- deficient to acrobic facies of the bottom water.