Microbialite development through the Ediacaran–Cambrian transition in China: Distribution, characteristics, and paleoceanographic implications

Widespread development of microbialites harbors a series clues about microbial activity, environmental condition, and aquatic chemistry. The Ediacaran-Cambrian transition draws extensive attention on the co-evolution complex life Earth's environment but associated microorganism has been largely ignored. In this study, we present high-resolution database with respect to spatial temporal distributions in China through terminal Ediacaran early Cambrian Period describe morphological petrological characteristics stromatolites thrombolites detail shed light evolutionary process carbonates. Microbialite experienced two thriving intervals during transition: latest Fortunian, Age 3 middle 4. columnar domical show no marked changes transition, stratiform exhibit notable decline time, likely caused by increasing bioturbation shelf environments. Meanwhile, evolved form large complicated structures featured meter-level mound morphology columnar-branching forms (fan-like/dendritic structures), indicating an improved adaptation (e.g., photosynthesis efficiency hydrodynamic conditions). Another remarkable change is emergence numbers calcified microfossils preserved within laminated/clotted mesostructures facies, compared that lack such unique structural features. For main control over calcification event, study stresses again essential role seawater chemistry (Mg/Ca molar ratios Ca 2+ concentrations) formation preservation microorganisms based previous insights elaborate their occurrence microstructures China. Neoproterozoic “aragonite-dolomite sea” “calcite (likely widely distributed 3) may have promoted generation original calcite mineralogy fossils, which stronger ability resist diagenetic dissolution substitution phosphatization silicification) than aragonite precursor. • We E-C transition. Detailed are described. Thrombolites structures, adaptation. primary mineralogical composition one potential reason for microfossils.