Sedimentary Environments and Biodiversity of Ichnofaunas at the pC/C-Boundary of the Yangtze Platform: Palaoecologic and Biostratigraphic Significance

本文概述了扬子台地pC/C界线段的沉积地层学和古生物学特征。沉积领域的古生态学解释及其痕迹化石组合将放在生物地层学背景下，从而增加对地球历史上这一关键时间间隔的理解。现代沉积学重新评价和解释有关层序和事件地层属性的关键剖面将确定主要的沉积环境并提供关键的古环境参数。某些鱼类群的首次出现以及典型鱼类群的组成和分布反映了后生动物进化的阶段（行为、生活方式和策略、种间和种内关系等），从而为非化石沉积物的后生动物进化提供了资料。近年来，一些鱼类群被用来作为碳/碳边界分带和全球对比的指标化石，并取得了不同的成功。在长江台地沉积物的许多剖面中，真正的生物地层学标志（如甲壳类、小壳类化石和早期三叶虫）与保存完好的鱼动物群共同出现的独特情况，首次使某些发生在pC/C边界上的鱼类群的真正生物地层学意义得以校准。

This proposal outlines sedimentologic-stratigraphic and palaeobiological aspects of the pC/C boundary interval of the Yantze Platform. Paleoecologic interpretations of the depositional realm and its trace fossil assemblage will be placed in a biostratigraphic context, thus adding to the understanding of this critical time interval in earth history. A modern sedimentological re-evaluation and interpretation of select key sections regarding sequence- and event-stratigrahic attributes will identify the dominant sedimentary environments and provide critical palaeoenvironmental parameters. The first appearances of certain ichnotaxa, and the composition and distribution of typical ichnoassemblages reflect evolutionary stages in the metazoan evolution (behavior, life styles and strategies, inter- and intraspecific relations etc.), and therefore supply data on the metazoan evolution in otherwise unfossilifeous sediments. Several ichnotaxa have recently been used with various succes as index fossils for pC/C boundary zonation and global correlation. The unique situation of a co-occurrence of true biostratigraphy markers (such as acritarchs, small shelly fossils and early trilobites) and well-preserved ichnofaunas in many sections of the Yangtze platform sediments allows, for the first time, the calibration of the true biostratigraphic significance of certain ichnotaxa occuring across the pC/C boundary.