LOWER CAMBRIAN STRATIGRAPHY OF CHENGJIANG, EASTERN YUNNAN, CHINA WITH SPECIAL NOTES ON CHINESEPARABADIELLA, MOROCCAN ABADIELLA AND AUSTRALIAN ABADIELLA HUOI
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Abstract:
Subdivision of the classic Lower Cambrian stratigraphy of Chengjiang County, eastern Yunnan, China, is revised in light of recent discoveries and interpretations of the regional stratigraphy, and recent interpretations of biotic changes across the Precambrian Cambrian boundary. Modification to lithostratigraphic nomenclature, chronostratigraphic zonation, and biostratigraphic zonation of Lower Cambrian units are summarized. As presently recognized, lithostratigraphic units are, in ascending order, the Yuhucun Formation (Meishucun Stage), the Heilinpu Formation (Qiongzhusian Stage), the Hongjingshao and Wulongqing formations (Canglangpuian Stage) and the Shanyicun Formation (Longwangmiaoan Stage). Biostratigraphically, this succession is divided into 12 assemblage zones and two subzones. All of the assemblage zones are recognizable throughout the Southwest China Platform, but the subzones are of local utility. The position of the Sinian (Neoproterozoic) Cambrian boundary in eastern Yunnan is tentatively placed at the base of the Xiaowaitoushan Member of the Yuhucun Formation, just below the first appearance of small shelly fossils. Chinese Parabadiella, Moroccan Abadiella and Australian Abadiella huoi are reviewed. We prefer to maintain Parabadiella and Abadiella as separate genera. Type specimens of these two genera are reillustrated. Australian Abadiella huoi is a new species of Wutingaspis jelli Chang sp. nov. and pik's (1975) Dolerolenus (?) sp nov. is a species referred to Parabadiella huoi Chang (1966). Parabadiella huoi is the oldest Cambrian trilobite not only in China but also in Australia. The stratigraphic position of Wutingaspis jelli in Australia and Abadiella in Morocco is equivalent to the upper part of the Wutingaspis Eoredlichia Zone in China.
