对国际地层委员会前寒武纪划分参考方案的简介及评述

Brief Introduction and Comment on the Special Reference to the Precambrian Subdivision by the International Commission on Stratigraphy

国际地层委员会最近公布了 2 0 0 4年全球地质年代表 ,并专门讨论了 2 0 0 4～ 2 0 0 8年前寒武纪划分参考方案。参考方案指出“应该根据唯一客观的物理标准——现存的岩石记录 ,对前寒武纪地质年表重新进行界定。前寒武纪的地层界线应标定于地层记录中的关键事件或转变点上 ,以突出反映地球系统演化的巨变。文中建议采用类似显生宙地层研究过程中所使用的“金钉子”法来确定前寒武纪界线。由于该文将对前寒武纪划分和整个前寒武纪研究工作带来重大影响 ,因此本文首先介绍了《参考方案》中有关前寒武纪划分原则和具体划分方案的新思路 ,对《参考方案》中值得商榷的问题进行了初步讨论 ,并对我国前寒武纪年代表制定中有关重点提出了建议。

A New Geologic Time Scale, with special reference to Precambrian and Neogene” written by Gradstein (Chair of ICS) et al. was published in the 1st issue, 2004 of “Episodes”. In this paper, the authors point out that “the Precambrian time scale should be redefined in terms of the only objective physical standard——the existant rock records. The boundaries should be placed at the key events or transitions in the stratigraphic record, to highlight important milestones in the evolution of our planet.” They suggest that the bounbaries of the Precambrian could be employed to the golden spike GSSP approach in the Phanerozoic. Because of the importance of the paper for the subdivision of the Precambrian and all Precambrian researches in the world, we firstly introduce the new ideas including subdivision principles, criteria and schemes of the above-mentioned article. Furthermore, a preliminary discussion has been done on some problems in the Special Reference, and suggestions are proposed for the establishment of the Precambrian Time Scale in China.