A reinterpretation of ore zoning in the Organ district, Dona Ana County, New Mexico
Virgil W. Lueth and Virginia T. McLemore
Metal and mineralogical zoning is defined in the northern portion of the Organ district. Zoning is present along the structurally-controlled Merrimac-Hilltop and Torpedo-Bennett mineralization trends. Copper-molybdenum porphyry-type deposits at the Torpedo mine and Organ copper deposit gave rise to copper skarns that are immediately adjacent to the porphyry systems. An outward progression continues to zinc skarns followed by zinc-lead replacement deposits and lead-zinc replacements, with significant silver values, that occur farthest from the mineralization source. Pb/Cu and Cu/Zn ratios best define metal zoning and fluid flow directions for sulfide-bearing deposits. High Cu/Zn and low Pb/Cu ratios are located at the source of hydrothermal fluids. The variation of the ratios is a function of relative solubilities between metal complex species. Gaps in the zoning sequence, represented by a lack of observed or developed mineral deposits represent areas of highest exploration potential. Fluorite-barite deposits in the Organ district are genetically unrelated to porphyry copper mineralization based on age constraints.
- Lueth, Virgil W.; McLemore, Virginia T., 1998, A reinterpretation of ore zoning in the Organ district, Dona Ana County, New Mexico, in: Las Cruces Country II, Mack, G. H.; Austin, G. S.; Barker, J. M., New Mexico Geological Society, Guidebook, 49th Field Conference, pp. 279-285.