Carbon releasing mechanisms and flux estimation in subducting slabs: Problems and progress

More than 98% of the global carbon is stored in the Earth's mantle and the core. The carbon in the Earth's interior could release to the surface by various magmatism, while the carbon on the surface can enter the Earth's interior along with the subduction of plates. Subducting slabs cannot carry all the stored carbon into the deep Earth. Different decarbonization mechanisms will release carbon out of the slabs during the subducting process. The carbon releasing mechanism and the flux in the subduction zones have profound impacts on the concentration of CO2 in the Earth's surface system which could change the habitability of the Earth. Here we summarized five decarbonization mechanisms : metamorphic decarbonization, carbonate dissolution, carbonate melting, sediments diapirism, and redox reaction. On the other hand, the carbon releasing fluxes in the subduction zones are still controversial at present. Therefore, we also reviewed the research progress and the problems for decarbonization mechanism and their flux estimation in the subduction zones to inspire new research methods to make a breakthrough of the deep carbon cycle in subduction zones in the future.