The Lower Cambrian black shales are well developed on the Yangtze Platform, but subdivision and correlation of these black shales remain unresolved, because of lack of index fossils. Eodiscoids, which are abundant at some horizons, are the only body fossils that can be applied to correlating the Lower Cambrian black shales. However, taxonomy of these eodiscoids from South China is very confused among the palaeontologists and its stratigraphic distribution remains unclear, thus limits its stratigraphic application. Based on the revised taxonomy and reviewed stratigraphic distribution of the Lower Cambrian eodiscoids on the Yangtze Platform, present study indicates that the five distinct eodiscoid species show high potential for stratigraphic correlations and their distributions are controlled essentially by palaeoenvironment. The results demonstrated that T. aclis and T. armatus occurred only in the Early Qiongzhusian, T. niutitangensis and T. tingi mainly occurred in the Late Qiongzhusian, but only T. tingi extended to the Early Canglangpuian. H. orientalis appeared in the Late Qiongzhusian, but are abundant in the Early Canglangpuian. Analyses of the palaeoenvironments indicate that sedimentary rate, sea-level change, seawater depth, redox condition of the bottom water are major environmental factors which control distribution of the eodiscoids. T. aclis and T. armatus occurred in the nearshore to offshore environments. T. niutitangensis and T. tingi were flourishing in the outer shelf, while a large number of H. orientalis occurred in the carbonate facies under the clear seawater with abundant phytoplankton from shelf-edge and outer shelf condition. No eodicoids appeared from the black carbonaceous shale under the deep euxinic anoxic condition from backshore and foreshore basins, and neither live in shallow water basin with high hydrodynamic energy and sedimentation rate.
About author: Yangtze Platform, Early Cambrian, Eodiscoids, stratigraphy, palaeogeography, ecoenvironment
About the first author Yang Aihua, born in 1976, was graduated and obtained her BS degree from Changchun College of Geosciences in 1999, got her MS degree from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences in 2002. Now she is a candidate for Ph. D. degree at Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences.
Cite this article:
. Stratigraphic distribution and its Palaeogeographic control on the Early Cambrian Eodiscoids on Yangtze Platform[J]. JOURNAL OF PALAEOGEOGRAPHY, 2005, 7(2): 219-232.
. Stratigraphic distribution and its Palaeogeographic control on the Early Cambrian Eodiscoids on Yangtze Platform[J]. JOPC, 2005, 7(2): 219-232.
