二叠纪地层研究述评

A Review of Permian Stratigraphy

近二十年来 ,全球和中国的二叠纪年代地层方案基本形成。层序地层、同位素年龄和磁性极性地层也获得系统的资料 ,所以国际二叠系对比的精度大为提高。不过年代地层单位的界线层型犹待厘定 ,还存在若干重要的对比问题。

This paper gives a brief account of some interesting aspects of Permian stratigraphy in China as well as in other regions. Approval of an integrated chronostratigraphic scheme to replace the traditional standard succession in the Urals is significant. This scheme will not only serve as a working template for the Subcommission in defining the GSSPs for intra Systemic boundaries following the concept and procedures of modern stratigraphy, but also as a catalyst for developing a more reliable global correlation of the Permian. Increasing data of magnetostratigraphy, isotopic ages and sequencestratigraphy make it possible to erect a correlation between the proposed standard and other Permian successions. In China, as a consequence of implementing multi categories of stratigraphic classification, a Chinese chronostratigraphic scheme consisting of three series and 8 stages was established based on updated data on Permian cono donts, fusulinids, ammonoids and palynomorphs. The well established chronostratigraphic units such as the stratotypes of the Permian Triassic boundary, the Changhsingian Stage, and even the Lopingian Series were basically accepted as the global standard of the Upper Permian. The base of the Permian System in China, which has been traditionally placed at basal level of the Kungurian Stage for more than half a century, is now in agreement with the international standard. However, the proposed international and Chinese chronostratigraphic units need to be enhanced through defining the GSSP for its basal boundary, refining the standard stratigraphic sequences, subdivisions and inter regional correlation. And correlation of post Artinskian successions is far from precise because of the strong biogeographic differentiation.