MIDDLE ORDOVICIAN BRACHIOPOD FAUNA OF SOUTHERN UPPER YANGTZE PLATFORM, SW CHINA

The Middle Ordovician rocks at Shuanghe, Changning, southeastern Sichuan Province and its vicinity are well developed, especially the Dashaba Formation, the upper part of the Middle Ordovician, which is characterized by the intercalations of yellowish green mudstone and brownish yellow silty mudstone with calcareous nodules and limestone lenses. This formation is different both lithologically and palaeontologically from its equivalent rocks, the Shihtzupu Formation in northern Guizhou Province and the Kuniutan Formation in western Hubei Province. In the Dashaba Formation, the beds yielding benthic shelly fossils (such as brachiopods and trilobites) and those graptolitic beds sandwiched each other several times, which are very helpful to determine the age of the shelly faunas. The graptolites belong to the Didymograptus murchisoni Biozone, latest Arenig to Llanvirn in age.

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Clc Number:

Q915.816