Stability of methane in reduced C-O-H fluid at 6.3 GPa and 1300-1400A degrees C

摘要

The composition of a reduced C-O-H fluid was studied by the method of chromatography-mass spectrometry under the conditions of 6.3 GPa, 1300-1400A degrees C, and fO(2) typical of the base of the subcratonic lithosphere. Fluids containing water (4.4-96.3 rel. %), methane (37.6-0.06 rel. %), and variable concentrations of ethane, propane, and butane were obtained in experiments. With increasing fO(2), the proportion of the CH4/C2H6 peak areas on chromatograms first increases and then decreases, whereas the CH4/C3H8 and CH4/C4H10 ratios continually decrease. The new data show that ethane and heavier HCs may be more stable to oxidation, than previously thought. Therefore, when reduced fluids pass the "redox-front," carbon is not completely released from the fluid and may be involved in diamond formation.