中国科学院南京地质古生物研究所机构知识库

Microfossils of the Ediacaran Doushantuo Formation in South China provide an important window onto the rapid diversification of marine eukaryotes after the terminal Cryogenian global glaciation. They also offer key data in the biostratigraphic subdivision and correlation of the lower-middle Ediacaran System. Previously published Doushantuo microfossils in South China were mostly from intra-shelf facies in the Yangtze Gorges area, shelf margin facies in the Weng'an area, and upper slope facies in the Zhangjiajie area, whereas paleontological data from shallow-water inner shelf facies have been rarely documented. In addition, previous data from South China leave a "barren zone" associated with the negative delta 13Ccarb excursion EN2 that impedes biostratigraphic correlation. To address these environmental and stratigraphic gaps, we conducted an integrated chemostratigraphic and biostratigraphic analysis of the Doushantuo Formation at the inner shelf Lianhuacun section in the eastern Shennongjia area of Hubei Provence, South China. The Lianhuacun fossils are preserved in chert nodules/bands of the lower Doushantuo Formation, precisely in a chemostratigraphic interval identified as EN2, indicating that the so-called "barren zone" is likely a taphonomic artifact. A total of 33 genera and 82 species are identified, including a new genus (Duospinosphaera gen. nov.) and seven new species (Duospinosphaera shennongjiaensis sp. nov., D. biformis sp. nov., Jixiania retorta sp. nov., Mengeosphaera mamma sp. nov., Sinosphaera exilis sp. nov., Tanarium columnatum sp. nov., and Weissiella concentrica sp. nov.). The Lianhuacun acanthomorphic acritarchs can be broadly assigned to the third microfossil assemblage zone (i.e., the Tanarium conoideum - Cavaspina basiconica Assemblage Zone) recognized on the basis of the Weng'an biota that is correlated with upper Member II of Doushantuo Formation in the Yangtze Gorges area, consistent with chemostratigraphic correlation between the Shennongjia and Yangtze Gorges areas. Thus, the so-called "barren zone" may be a poorly preserved part of the third microfossil assemblage zone. Alternatively, it may represent a new and yet unnamed microfossil assemblage zone between the third and the overlying Tanarium pycnacanthum - Ceratosphaeridium glaberosum Assemblage Zone. Regardless, the new data presented here fill important gaps in the geographical, paleoenvironmental, and stratigraphic distributions of Ediacaran acanthomorphic acritarchs in South China. As such, they facilitate integrative chemostratigraphic and biostratigraphic correlation of Ediacaran strata at regional and global scales.