Cryogenic Raman Spectroscopic Studies on Common Ore-forming Fluid Systems

The composition and properties of ore-forming fluids are key to understanding the mechanisms of mineralization in ore deposits. These characteristics can be understood by studying fluid inclusions. Hydrates in fluid inclusions containing NaCl–H 2O and MgCl 2–H 2O were studied using cryogenic Raman spectroscopy. The intensity ratio of peaks at 3401, 3464, 3514, and 3090 cm ？1 shows a positive correlation with the concentration of hydrates in the inclusions, as does the ratio of the total integrated area of the MgCl 2 hydrate peak (3514 cm ？1) to the 3090 cm ？1 peak with the concentration of MgCl 2 (correlation coefficient >0.90). These correlations are important in the quantitative analysis of MgCl 2 in synthetic and natural NaCl–MgCl 2–CaCl 2–H 2O-bearing fluid inclusions. Semi-quantitative analysis of NaCl–MgCl 2–H 2O solutions indicates that peaks at 3437 and 3537 cm ？1 reflect the presence of NaCl in the solution. Further, a peak at 3514 cm ？1 is indicative of the presence of MgCl 2. The relative intensities of these peaks may be related to the relative abundances of NaCl and MgCl 2. A quantitative attempt was made on NaCl–MgCl 2–CaCl 2–H 2O system, but it was found that quantifying NaCl, MgCl 2 and CaCl 2 separately in NaCl–MgCl 2–CaCl 2–H 2O system by the secondary freezing method is difficult. View Full-Tex