Abstract:

Abstract:   Cycling of carbon into and out of the mantle plays a key role in the global carbon cycle and influences the CO2 budget of the Earths atmosphere. Subduction introduces carbon into the mantle, while volcanic outgassing releases it to the surface. Oceanic crust is mainly composed of basalts, and hydrothermal altered basalts contains several wt％ of carbonates (average 3wt％), which is a huge carbon sink for global carbon cycling. Carbonates (in the form of veins) within basalts can be delivered to the upper mantle until 300 km during oceanic crust subduction, thus produced carbonated eclogites. Partial melting of carbonated eclogites plays an important role in arc magmatism and volcanic outgassing. In this paper, we summarize up to now all reports of ultrahighpressure metamorphic areas of natural carbonated eclogite samples and compare with the recent progress in experimental petrology of altered MORB plus carbonate minerals and reach some basic conclusions of how carbonate minerals interact with silicate system (eclogitic) with progressively elevated temperature and pressure in subduction zones. What is more, we summarize the current research progress of phase equilibrium calculation of carbonated eclogites in NCFMASH+CO2 system and the H2OCO2 activity model, thus forecast the future phase relationship calculation of NCFMASH+CO2 system, which is important for global carbon cycling.

Key words:

Key words: carbon cycling; carbonated eclogites; phase equilibrium calculation; subduction