INTERIOR-EXTERIOR EXCHANGE OF WATER AND CARBON FROM ARCHEAN TO PRESENT-DAY: INSIGHTS FROM GEODYNAMICS MODELING (Invited Presentation)

I hereby present recent achievements in understanding the water and carbon cycles across the Earth’s deep interior. It employs geodynamic modelling to investigate the potential role of these cycles in understanding long-term global change associated with the dynamics of Earth’s deep interior. The water cycle in the deep interior may be controlled by the subduction zone, which is balanced between water uptake associated with the subducting oceanic crust and water release caused by the metamorphic reaction along with the subducting plate (i.e., dehydration). This balance causes approximately 1.5 metres of relative sea-level change in approximately one billion years, which appears to be consistent with that measured by the drilling core analysis. Furthermore, in order to ascertain this relative sea-level change, the Earth’s mantle should be capable of storing approximately five times the volume of ocean that exists at the present day during the early Earth stage. With regard to the carbon cycle, the carbon budget between the surface and the deep interior may also be controlled by the subduction zone system, resulting in a similar mechanism to that observed in the water cycle. It is important to consider the carbon release (carbon dioxide) caused by the metamorphic reaction with subducting plates (i.e., decarbonation) when examining the atmospheric-ocean temperature. This is because the liquid water can be found, which allows the plate subduction system to play a significant role in understanding the long-term global change on the surface.