THE CHEMICAL COMPOSITIONS OF VOLATILES IN UPPER MANTLE AND THEIR IMPLICATION FOR HYDROCARBON GENERATION
地幔流体化学组成与成烃

Mantle fluids in supercritical state possess high dissolving and diffusing capacity, which are the important transporting carrier of energy in earth interior, their chemical compositions vary in a large range with the evolution processes of mantle, and can be distinguished as the primitive fluid in upper mantle, the fluid of mantle metasomatism and etc. The chemical composition of primitive fluid in upper mantle are related to the mantle reservoir, the primitive fluid in upper mantle with a primitive mantle-like reservoir is dominated by CO with secondary amounts of CO2 and H2; a depleted mantle reservoir shows a dominant CO2 with minor amounts of CO and H2 in primitive fluid in upper mantle, and an enriched mantle reservoir is enriched in H2. Meanwhile the fluids of mantle metasomatism were mixed by the recycled crustal fluid components beneath eastern China. Mantle fluids have preserved a certain amount light hydrocarbon, such as CH4, C2H6 etc. and high weight hydrocarbon, including an amount of primordial hydrocarbon, moreover, mantle fluid enriched in H2 and heat can provide the ample hydrogen and heat sources in hydrocarbon generation of kerogen and promote source rocks to expel hydrocarbons and migration.