Abstract:

The microthermometric analysis results of fluid inclusions trapped in Au-mineralized quartz in Dak Rong-A Luoi district show two homogenisation temperature asemblages which indicate two mineralisation stages. In the fist stage, the ore accumulation occurs as the result of a mixture between metamophic (majority) and magmatic (minority) fluids, in conditions of high temperature (220-380oC), low-medium salinity (<16.3%), high depth (2-3.8km) and low fluid density (0.65-0.9g/cm3. In the later stage, the ore accumulated as the result of a mixture between metamophic fluids (majority) and meteoric water (minority), which is characterized by low temperature (125-200oC), low salinity (<10%), low-medium depth (1-2km) and high fluid density (0,9-1g/cm3).