In deep-formed deposits, boiling occurs at temperatures that may exceed 300☌, and ore is generally deposited between 400 and 1,000 m from the paleowater table as fluids rise within the area of liquid-vapor immiscibility. In shallow-formed deposits boiling fluids rise to depths of <500 m below the paleowater table, and ore occupies a vertical range of a few hundred meters. Three end-member types are recognized: shallow with boiling, deep with boiling, and deep without boiling. Rather, these results are best accounted for by a significant contribution of magmatic waters to the deep fluid, subsequently modified by water-rock interaction, boiling, and mixing with meteoric water.Ī classification of low-sulfidation deposits of Mexico is presented based on depth of formation and whether or not boiling is thought to have occurred in the system. Boiling and/or water-rock interaction processes alone cannot explain adequately the consistently heavy oxygen isotope signatures of Mexican low-sulfidation deposits. Fluids responsible for precious metal and base metal deposition contain consistently heavy oxygen isotope signatures and shifts as high as +10 to +20 per mil from the meteoric water line, regardless of host rock type. New oxygen and hydrogen isotope data are presented for seven deposits. The data suggest that low-sulfidation epithermal deposits in Mexico comprise both meteoric waters and magmatic waters, with a significant contribution of H 2S of magmatic origin. H 2S/Ar show a correlation between N 2 and H 2S concentrations. The N 2/Ar ratios of sulfide mineral fluid inclusions are all higher than that of air-saturated water, indicating a mag-matic source, whereas a significant proportion of inclusions in barren gangue minerals have N 2/Ar ratios near that of air-saturated water. fraps 2.9. Silver/gold and Ag + Au/Pb + Zn + Cu ratios correlate with fluid inclusion salinity, a relationship that underscores the importance of chloride complexing in base metal transport and polymetallic mineralization.įluid inclusion gas chemistry of 21 low-sulfidation epithermal deposits plotted on N 2-Ar-He and N 2-Ar-CH 4 diagrams indicate that meteoric, mantle or evolved crustal, and magmatic fluids were present in the ore-forming hydrothermal systems, although in different proportions in individual deposits. Salinities are typically high in fluids included in sphalerite, suggesting a genetic relationship between base metal mineralization and saline fluids. Precious metal deposits typically have inclusion salinities that range from 0 to 7.5 wt percent NaCl equiv, whereas base metal-rich deposits have salinities that are as high as 23 wt percent NaCl equiv. Note: The RhE test methods covered by this TG cannot resolve between GHS optional. TG PRO 2.9.9 PROFESSIONALFluid inclusion and metal-ratio data have been compiled for 52 low-sulfidation precious metal and base metal-rich low-sulfidation epithermal deposits in Mexico. The medical professional should maintain the confidentiality of the.
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