THE RELATIONSHIP OF EPITHERMAL AU-AG-CU BEARING FLUIDS TO MAGMATISM IN THE MOGOLLON DATIL VOLCANIC FIELD, NEW MEXICO

The Mogollon Mining District (MMD) is characterized by epithermal deposits of silver-gold-copper bearing quartz-calcite veins located in the high angle normal faults of the Bursum Caldera in the western Mogollon Datil Volcanic Field. Radiometric dating of the vein fill suggests mineralization occurred between 15-18 Ma, during a period of volcanic quiescence in southern New Mexico. Several studies have presented fluid inclusion and salinity studies to determine fluid temperatures, conditions and suggest fluid source during mineralization. These data suggest that multiple generations of fluids with differing temperatures, but consistent salinity was present in the vein fill. Here, we used new whole rock and mineral trace element data from both the mineralized vein fill and host volcanic rocks combined with new U-Pb calcite geochronology, radiogenic isotope ratios, and carbon and oxygen isotope values to investigate the sources of the different generations of fluids in the largest vein in MMD, the Queen vein. Trace element data suggest that the vein fill carbonates geochemically can be derived from the host volcanic rocks, in particular the Last Chance and Mineral Creek andesites. Oxygen and carbon isotope values of calcite represent normal intermediate igneous rocks influenced by groundwater. We suggest that calcite represents three generations of fluids leached from the local volcanic rocks. We suggest that the source of this fluid is a mixture of dominantly magmatic fluids influenced by groundwater at shallow depths.