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

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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.