1 Carbon Isotopic Data Validate the New Model of Carbon Turnover

A new global redox carbon cycle model is suggested. It claims that lithosphere plates’ movement exerts an impact on photosynthesis development. The impact is realized via periodic injections of CO2 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 (CO2 + HCO3- + CO32-) into the reduced state produced in photosynthesis and in the following transformations. 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 13C isotope discrimination in photosynthesis used for modern plants. The periodicity of isotopic characteristics correlates with the periodicity of climatic changes, mass extinctions, with the irregularity of stratigraphic distribution of rocks rich in organic matter and other periodic events in biosphere. The model explains, how the evolution of photosynthesis resulted in the accumulation of oxygen in the atmosphere and sedimentary organic matter in the Earth's crust, and how these changes eventually brought the global carbon cycle system to an ecological compensation point. At this point all the parameters of the system stabilized and began to oscillate around a certain stationary state.