Microbiota and Microbial Mats within Ancient Stromatolites in South China

Abstract

Abundant stromatolites have been found from the Neoproterozoic Jiudingshan and Niyuan formations in northern Jiangsu Province and northern Anhui Province, South China. The stromatolites are mostly stratiform, rarely small domed and conical (Conophyton-like), with more or less clearly laminated structures. Well-preserved, silicified microbial mats containing mat-building microfossils have been found in small domed, conical, and stratiform stromatolites of the Neoproterozoic Jiudingshan Formation and Niyuan Formation. Main mat-producing species are Gloeodiniopsis suxianensis among the coccoids, and Siphonophycus inornatum and Siphonophycus sp. among the filamentous cyanophytes, although Myxococcoides sp., Leiosphaeridia sp., and Eoentophysalis ­robusta are often included in the community. Present study indicates that the morphology of a microbial mat, particularly first microbial mat, plays an important role in the morphogenesis of stromatolites, and the community dominated by Gloeodiniopsis suxianensis, which is largely confined to stratiform stromatolites, may represent an intertide setting.