摘要
前寒武纪一寒武纪界线地层在扬子地台发育良好、分布广泛，并有包括微体植物群、海藻、瓶形原生物、具硬体动物及‘澄江动物群’等化石的发现。因而，扬子地台成为研究前寒武纪－寒武纪界线生物地层的代表地区之一。基于对扬子地台前寒武纪－寒武纪界线地层已知微体植物化石记录的回顾和论定，总结概括了下寒武统微体植物化石组合：寒武系最底部硅质磷块岩中的Ｍｉｃｒｈｙｓｔｒｉｄｉｕｍ－Ｐａｒａｃｙｍａｔｉｏｓｐｈａｅｒａ－Ｍｅｇａｔｈｒｉｘ组合和较高层位页岩的Ｓｋｉａｇｉａ－Ａｎｎｕｌｕｍ－Ａｒｃｈａｅｏｄｉｓｃｉｎａ组合。它们分别与Ａｎａｂａｒｉｔｅｓ－Ｃｉｒｃｏｔｈｅｃａ－Ｐｒｏｔｏｈｅｒｔｚｉｎａ小壳动物化石带和Ｐａｒａｂａｄｉｅｌｌａ及Ｅｏｒｅｄｌｉｃｈｉａ三叶虫带相对应。与东欧地台疑源类生物地层相对照，扬子地台Ｍｉｃｒｈｙｓｔｒｉｄｉｕｍ－Ｐａｒａｃｙｍａｔｉｏｓｐｈａｅｒａ－Ｍｅｇａｔｈｒｉｘ组合的纵向分布大体和东欧地台Ａｓｔｅｒｉｄｉｕｍｔｏｒｎａｔｕｍ－Ｃｏｍａｓｐｈａｅｒｉｄｉｕｍｖｅｌｖｅｔｕｍ组合带相一致，而以上两地台的化石组合产出层位可能都略高于纽芬兰东部剖面，依据Ｐｈｙｃｏｄｅｓｐｅｄｕｍ所厘定的寒武系底界?
The deposited strata within the Precambrian--Camrian transition are well developed and widely distributed in the Yangtze Platform, China. The fossils including microflora,seaweed,vase-like protists, hard part-bearing fauna and 'Chengjiang fauna' have been discovered from the Precambrian-Cambrian boundary strata of the Yangtze Platform.Therefore,the Yangtze Platform has become one of the representative areas for studying global events in biosphere, geosphere and atmosphere duriboundary stfata the Precambrian-Cambrian tional period and for determing the Precambrian - Cambrian boundary. The microflora obtained from carbonate, shale, chert and phosphorite of Precambrian-Cambrian boundary strata in the Yangtze Platform are reviewed and qualified in this paper. Two marked microfossil assemblages of Early Cambrian are summarized. One is the Micrhystridium -- Paracymatiosphaera-- Megathrix assemblage from siliceous phosphorites of the lowest Cambrian and the other is Skiagian--Annulum -- Archaeodiscina assemblage from shale in higher level of the lower Cambrian. They are contaporaneous with Anabarites --Circotheca-- Protohertzina small shelly fossil zone and Parabadiella, Eoredlichia trilobite zone respactively. In Yangtze Platform, it is characterized by that a large number of specimens of Micrhystridium complex, including Micrhystridium regulars, M. apliatum, Filisphaeridium echinulatum and F. minutum, commoly are discovered from chens intercalated in carbonate of Early Cambrian.The surprising occurrence of abundant Micrhystridium regulare and some coccoid algae normally indicated the lowest horizon of Cambrian. In comparison with acritarch biostratigraphy of East Europe Platform,it is recognized here that tile oh1Jonostratigraphic distribution of Micrhystridium-Paracymaof Asteridium tornatum-Comaspheridium velvetum biozone in East Europe Platform,and both are probably a little higher than the now favoured boundary level at the appearance of Phycodes pedum in eastern Newfoundland.
出处
《地层学杂志》
CSCD
北大核心
1995年第4期299-307,共9页
Journal of Stratigraphy
基金
中国科学院古生物与古人类学科基础研究特别支持费(930902)资助
