全球奥陶系年代地层学的研究——进展与问题

STUDY ON GLOBAL ORDOVICIAN CHRONOSTRATICRAPHY——PROGRESS AND PROBLEMS

综合评述了最近几年全球奥陶系年代地层研究方面的进展与问题。着重讨论了全球奥陶系统一年代地层表中每个统(包括厘定的“阿伦尼克”、“兰维恩—兰得罗”、“卡拉道克”和“阿什极尔”)的范围和可能选择作为划分统和阶的界线标志的生物层或带的位置,指出了当前我国奥陶系年代地层研究中存在的问题。基于全球奥陶系年代地层划分的原则和趋势以及我国广大地质工作者在过去10年中所积累的有关资料,提出了我国及全球奥陶系年代地层的划分方案。

This paper comprehensively reviews the advances and problems in the study of global Ordovician chronostratigrapy for recent years. The discussion is centre on the scope for each series, including the revised 'Arenig', 'Llanvirn -Llandeilo' , 'Caradoc'and 'Ashgill', within a global unified Ordovician chronostratigraphic scale,and the biohorizon or zonal level,which is probably selected as a mark for the subdivision of each series and stage boundary. The problems are indicated regarding the study of Ordovician chronostratigraphy in China at present. A dual ordovician chronostratigraphic scheme both for China and the world is present on the basis of the principal and trend of global Ordovician chronostratigraphic subdivision and related data accumulated by many Chinese geologists over a decade or more.