Sedimentary characteristics of Ediacaran microbialite in the Yangtze Platform, South China: implications for the evolution of early life

Clarifying the sedimentary characteristics of the Precambrian microbialite is crucial for understanding the evolution of early life on Earth. In the study, the sedimentary, mineralogical and geochemistry characteristics of microbial dolomite at the Ediacaran in the Upper Yangtze Block are analyzed. The results show that the late Ediacaran in the Upper Yangtze is a rimmed carbonate platform. The microbialite inside the semi-restricted platform is small and sparse, with low residual organic matter, while microbialite at the platform margin is large and dense, with high residual organic matter. The in- situ major elements, rare earth elements, C/O isotopes, and mineral assemble of microbialite indicate significant hydrothermal activity at the platform margin. Under the influence of hydrothermal activity, microbialite at the platform margin are enriched in Fe, Mn, P_EF, Ba_EF, Ni_EF, Cu_EF, Co_EF, Zn_EF, with higher levels of Na_EF, K_EF, Mg_EF and U_EF, Mo_EF, V_EF, indicating a sedimentary environment with sufficient nutrients, higher salinity, higher seawater temperature and lower oxygen. It can be concluded that environments significantly influenced by hydrothermal activity during the late Neoproterozoic were more suitable for microbial habitation, which may also suggest the origin of early life on Earth.