Carbon Isotopic Data Validate the New Model of Carbon Turnover

Abstract

A new global redox carbon cycle model is suggested. It claims that lithospheric plates' movement exerts an impact on photosynthesis development. The impact is realized via periodic injections of CO 2 coming from zones of plates' collisions. Carbon dioxide is derived from oxidation of sedimentary organic carbon in thermochemical sulfate reduction proceeding in subduction zones. Carbon turnover is considered as a conversion of the element from the oxidized state (CO 2 + HCO 3 -+ CO 3 -) into the reduced state produced in photosynthesis and in the following transformation. The isotopic data confirm the validity of the model. They explain the observed correlation of carbon isotope composition of sedimentary organic matter with geologic age. It was found that the difference between carbon isotope composition of organic matter and that of coeval carbonates is an analog of the carbon 13 C isotope discrimination in photosynthesis used for modern plants. The periodicity of isotopic characteristics correlates with periodicity of climatic changes, mass extinctions, with the irregularity of stratigraphic distribution of rocks rich in organic matter and other periodic events in biosphere.