Evolution of Isotopic Carbon Dioxide–Water Systems in Lithogenesis: Communication 1. Sedimentogenesis and Diagenesis

Isotope-geochemical features of the formation of carbon and oxygen isotopic compositions in sedimentary and diagenetic carbonates are considered. Isotopic criteria for the identification of early diagenesis zone are proposed. The transition from sedimentogenesis to diagenesis (upper boundary of the early diagenesis zone) is accompanied by the alteration of carbon isotopic composition in the HCO^–_{3(hydrosphere)}–HCO^–_{3(pore water of sediment)}system. The lower boundary of early diagenesis zone is registered by the alteration of oxygen isotopic composition in the pore water of sediments and authigenic carbonates.