THE DISCOVERY OF A MICROPALEOFLORA IN THE DABIE GROUP AND ITS AGE

The Dabie Group distributed in northeastern Hubei province is composed of thick metamorphic strata bearing a banded siliceous ironformation. It is covered unconformably by the phosphorus-bearing bed at the base of the Hong’an Group and its base is not found. It is one of the oldest strata, located between the South and North China terrains. In recent years, the authors have for the first time found a micropaleoflora, which contains ten genera and fourteen species. The main species are: Margominuscula tennela Naum., M. antiqua Naum., Leiominuscula minuta Naum., L. incrassata Sin et Liu, Trachyminuscula microrugosa Naum., Leiopsophosphaera sp., Zonosphaeridium minutum Sin, Dictyosphaera sp., Trematosphaeridium minutum Sin et Liu, Polyporata obsoleta Sin et Liu, Lignum punctulosum Sin et Liu,? Eosynevhococcus moorei Hofmann, etc. On the basis of regional stratigraphic correlation, isotope dating and an analysis of sediments and geological events, the authors consider that the age of the Dabie Group is early Proterozoic to late Archean.