CO2-CH4 FLUIDS AND GOLD MINERALIZATION: SOUTHERN MARGIN OF ALTAY, CHINA AND MURUNTAU OF UZBEKISTAN

Abstract

Gold Mineralization in orogenic gold deposits is closely related to H2O-CO2 fluids. However, aqueous-free CO2-CH4 fluids are also important in some gold deposits of the Central Asia metallogeny province, based on fluid inclusion study on gold deposits of southern margin of Altay in China and Muruntau gold deposit in Uzbekistan. XCH4 of CO2-CH4 fluids at Sarekoubu gold deposit can be up to 0.20 - 0.23, and those in the Muruntau are 0.07 - 0.23. The role of CH4 in fluids is to enlarge the mixing area of fluids, and is in favor of gold enrichment. The significance of CO2 fluids in gold mineralzation includes three aspects, that is, including to balance pH range in ore-forming fluid and retain gold content in fluid so as to be complexed with sulfur, to enlarge temperature ranges of critical fluid, and to increase immiscible region of fluid. CH4 is significant for immiscibility, and plays an important role for gold enrichment.