Abstract:

Carbonic fluids (CO2CH4N2 system fluids) were commonly found in mantle lherzolite and low crust granulite. Recent study shows that carbonic fluids are abundant in Late Paleozoic oreforming environment in Southern Altaides. Not only were the oreforming related carbonic fluid inclusions found in orogenic gold deposits, but also the coeval orogenicmetamorphic carbonic fluid inclusions were found in VMS deposits. The trapping temperatures of carbonic fluid inclusions may be higher than 2543945 ℃, and pressures higher than 150320 MPa, based on associated CO2rich (LCO2LH2O) and H2OCO2 inclusions (LH2OLCO2); while those of metamorphic carbonic fluids in VMS may be higher than 209430 ℃ and 180300 MPa, respectively. The trapping temperatures and pressures estimated from carbonic inclusions are approximate to those calculated from phase equilibrium of metamorphic zones in the area. Carbonic fluids were rooted in regional metamorphism, and played a role in the mineralization related to orogenic gold deposits and metamorphicreconstruction of VMS deposits.

Key words: oreforming environment, carbonic fluids, metamorphism, Southern Altaides