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古生代和中生代之间的界线,长期以来是国际地科联(IUGS)国际地层委员会关注的焦点。由于上述地层放射性年龄测定有许多问题,磁极性年代表又未下延至三叠纪,因而,具有足够精度的测定年代的唯一方法,是由生物年代学所提供。本文概述了年代地层定义和层型的进展。作者采用一个与地层委员会的自身指导原则颇为不同的方法,主张把界线放在Otoceras层的底部,这层作为最老的三叠纪层位。
The boundary between Paleozoic and Mesozoic has long been the focus of attention of the IUGS International Stratigraphy Commission. Because of the many problems associated with the determination of the radioactive age of the above strata, the magnetic polarity dating did not extend to the Triassic, and the only method of dating with sufficient accuracy was provided by the Biochronology. This article outlines the evolution of stratigraphic definition and stratification in the age. The author adopts a method that is quite different from its own guiding principle of the formation committee, and advocates placing the boundary at the bottom of the Otoceras layer, which is the oldest layer of the Triassic.