Magnetostratigraphy of the Precambrian-Cambrian Boundary Section at Meishucun, China

昆明附近中国西南部的一个台地碳酸盐岩和磷灰岩序列包含前寒武系-寒武系界线，并从岩性和动物群含量方面进行了深入的研究。它已被提议作为边界的全球层型。我们已经获得了初步的磁性地层学数据，这些数据显示了8次反转，并产生了一个不同于迄今在南中国地块观察到的显生界岩石的古极点。这项提案要求提供资金，在几个平行的区段额外收集1600个古地磁样品，以测试初步的磁性地层极性确定。有希望的初步数据表明，这一段可以为前寒武纪-寒武纪界线的磁性地层学提供一个标准，可以与其他段进行比较(例如，在西伯利亚、澳大利亚、蒙古、北美、欧洲或摩洛哥)。考虑到这一界线与各种壳体化石组合的首次出现有关，它是地层学和地球历史上最重要的特征。中国边界段可靠的反转记录将具有重要的内部对比价值。

A sequence of platform carbonates and phosphorites in southwest China, near Kunming, contains the Precambrian-Cambrian boundary and is well studied in terms of lithologies and faunal content. It has been proposed as a global stratotype for the boundary. We have obtained preliminary magnetostratigraphic data which show eight reversals and yield a paleopole which is unlike any paleopoles thus far observed for the South China block for any Phanerozoic rocks. This proposal requests funds to collect an additional 1600 paleomagnetic samples over several parallel sections, in order to test the preliminary magnetostratigraphic polarity determinations. The promising preliminary data suggest that this section could provide a standard for the magnetostratigraphy of the Precambrian-Cambrian boundary, with which other sections could be compared (e.g., in Siberia, Australia, Mongolia, North America, Europe or Morocco). Given that the boundary is associated with the first appearance of diverse shelly fossil assemblages, it is a feature of primary importance in stratigraphy and earth history. A reliable reversal record for the Chinese boundary section would be of great value in internal correlation.