Knoll A H
Botanical Museum, Harvard University, Cambridge, MA 02138, USA.
Precambrian Res. 2000 Mar;100(1-3):3-20. doi: 10.1016/s0301-9268(99)00067-4.
In 1989, the International Commission on Stratigraphy established a Working Group on the Terminal Proterozoic Period. Nine years of intensive, multidisciplinary research by scientists from some two dozen countries have markedly improved the framework for the correlation and calibration of latest Proterozoic events. Three principal phenomena--the Marinoan ice age, Ediacaran animal diversification, and the beginning of the Cambrian Period--specify the limits and character of this interval, but chemostratigraphy and biostratigraphy based on single-celled microfossils (acritarchs), integrated with high-resolution radiometric dates, provide the temporal framework necessary to order and evaluate terminal Proterozoic tectonic, biogeochemical, climatic, and biological events. These data also provide a rational basis for choosing the Global Stratotype Section and Point (GSSP) that will define the beginning of this period. A comparable level of stratigraphic resolution may be achievable for the preceding Cryogenian Period, providing an opportunity to define this interval, as well, in chronostratigraphic terms--perhaps bounded at beginning and end by the onset of Sturtian glaciation and the decay of Marinoan ice sheets, respectively. Limited paleontological, isotopic, and radiometric data additionally suggest a real but more distant prospect of lower Neoproterozoic correlation and stratigraphic subdivision.
1989年，国际地层委员会成立了新元古代末期工作组。来自约二十几个国家的科学家进行了九年密集的多学科研究，显著改善了新元古代晚期事件对比和校准的框架。三个主要现象——马林诺冰期、埃迪卡拉纪动物多样化以及寒武纪的开始——确定了这一时期的界限和特征，但基于单细胞微体化石（疑源类）的化学地层学和生物地层学，与高分辨率放射性测年相结合，提供了对新元古代末期构造、生物地球化学、气候和生物事件进行排序和评估所需的时间框架。这些数据也为选择将定义这一时期开始的全球层型剖面和点位（金钉子）提供了合理依据。对于之前的成冰纪，可能也可实现类似水平的地层分辨率，从而有机会以年代地层学术语定义这一时期——其起止界限或许分别为斯图尔特冰期的开始和马林诺冰盖的消退。有限的古生物学、同位素和放射性数据还表明，新元古代早期对比和地层细分虽有难度但前景可期。
