A Gunflint type of microfossil assemblage from early Proterozoic stromatolitic cherts in China

Abstract

A well-preserved early Proterozoic microfossil assemblage dominated by a filamentous form comparable with Gunflintia minuta Barghoorn and a coccoid form comparable with Huroniospora Barghoorn has been discovered in silicified stratiform stromatolites of the Dahongyu Formation, Changcheng Group, northern Hebei Province, China. It is the oldest in situ microfossil assemblage in China. The famous Gunflint fossils, from the Gunflint Iron Formation, Ontario¹, were the first well preserved and relatively diverse Precambrian microbiota to be described^2,3. Several other Precambrian microfossil assemblages are now known, but the Gunflint type has thus far been found in only a few other localities: the Duck Creek Dolomite, northwestern Australia⁴; the Frere Formation, western Australia⁵; and the Tyler Formation, northern Michigan, USA⁶. They are all early Proterozoic. The discovery indicates that the stromatolitic benthic microbiota of the Gunflint type had a cosmopolitan distribution in time between 2,000 and 1,700 Myr ago, and may have both palaeoecological and stratigraphical significance.