The Culampaj auriferous district is located in the northern sector of the eastern edge of the homonymous hill, Catamarca Province, Argentina. Tajo Largo mine is situated in the southern flank of Las Minas gulch at an approximate height of 3.600 m above sea level. In the studied area main outcrops are orthogneiss rocks of Chango Real Formation. The ore mineral is native gold with a lesser amount of pyrite, chalcopyrite, haematite, limonite, malachite, azurite and covellite. These ore mineral assemblages are disseminated in quartz veins filling tension fractures in the host orthogneiss._x000D_
Several types of inclusions have been recognised, including three phase H2O-CO2liq-CO2vap inclusions, polyphase inclusions with H2O-CO2 and one or more solid phases, and two phase aqueous inclusions._x000D_
In the three phase H2O-CO2liq-CO2vap inclusions the Tmclath is about 1C and the CO2 liquid-vapour homogenisation occurs at 26 - 28C, to liquid phase. The homogenisation temperature of H2O-CO2 occurs at 365 - 380C in the aqueous phase. This set of data defined a solution with a salinity of 14, 4 wt per cent NaCl equivalent and a density of 0.84 g/cm3. In the two phase aqueous inclusions the melting temperature (Tm) of -5.4C and the eutectic point (Te) in -38C indicates a salinity of about 7.5 wt per cent NaCl equivalent, with the probable presence of Ca2+. Density of fluid is about 0.83 g/cm3. Homogenisation temperature ranges between 260 and 280C. The pressure, temperature and salinity of fluids in the polyphase inclusions suggest an early fluid of high density and high salinity._x000D_
The three-phase fluid inclusions may be the result of an unmixing-phase separation of post magmatic hydrothermal fluid due to pressure decrease along fractures._x000D_
It is suggested that the deposit was formed during the late magmatic hydrothermal stage genetically linked to granitic rocks and can be comparable with the intrusion-related gold system of Baker (2003).