摘要
The Baiyanghe deposit is the largest sub-volcanic U-Be deposit discovered recently in Asia.Fluorite,which is the main associated mineral of U,Be minerals,has been elaborately divided into four stages according to the colors,textures and the crosscut relationships.Fluid inclusion experiment was conducted to obtain information of ore-forming fluid.The results show that homogenization temperatures of fluid inclusions at different stages of fluorite veins range from 90℃to 176℃,and main homogenization temperature peaks range from 120~150℃, indicating that the Baiyanghe U-Be deposit is an epithermal deposit.The majority of inclusions from four stages of fluorite are vapor CO2-liquid H2O two phase inclusions and CO2clathrate formed during the cooling of the inclusions.However,there is no method to calculate salinitiesof such inclusions.An assumption is made in this paper that liquid CO2content in the vaporCO2-liquid H2O two-phase(V-L)inclusionsisinfinitely close to 0 to get salinities of such inclusions.The obtained salinitiesw(NaCleq)range from 4.69%to 19.72%for all inclusions and the average salinityw(NaCleq)of each stage of fluorite is approximately 10%.The homogenization temperatures varied slightly and the average salinities changed nominally.Therefore,meteoric water could not be the only source of ore-forming fluid.Taking the geological setting into account,the authors hold that high salinity magmatic water might have been an important source of ore-forming fluid to form a mixed salinityw(NaCleq)of around 10%.