Early Diagenesis in the Lacustrine Ostracods from the Songliao Basin 91.35 Million Years Ago and Its Geological Implications

Diagenesis is a double-edged sword of geochemical recordings. It makes us always doubt about the representativeness many indicators, especially isotope and mineral related. also provides window to explore biogeochemical processes at water–rock interface, which are related interactions between hydrosphere, biosphere, lithosphere. In this study, we identified microbial early diagenesis in lacustrine ostracods from Songliao Basin 91.35 million years ago by using situ mineralogical carbon analytical methods. Our results suggest multiple biological early-diagenesis formation ferric methane transition zone (FMTZ) sulfate-poor pore water, conducive dolomite ankerite. These secondary carbonate minerals dissimilatory iron reduction methanogenesis have heavier isotopic compositions than calcified ostracod shell water column might bring interferences parameters ostracods.