New Mexico Geological Society Annual Spring Meeting — Abstracts

Current economic conditions have made epithetmal or "bonanza" Au-Ag deposits attractive exploration targets. The emphasis on exploration for such deposits has given impetus to: (1) resurgence in research on the epithermal model; (2) intensive investigations of the geochemistry
of active hot springs environments and (3) the application of new exploration techniques in fos sil geothermal zones.

While research and exploration have put certain epithermal models in focus, understanding the processes of deposition is, the author believes, even more critical in finding gold and silver bonanzas.

Zoning - of alteration, vei n mineralogy, temperature of deposition, metal content and trace element va'lues as related to structure and host rock formations - is crucial. Understanding zoning provides "road signs" to ore.

Notable recent epithermal discoveries include Homestake's Mclaughlin deposit in northern California and St. Joe's El Indio deposit in Chile. Known epithermal districts throughout the world are being scientifically re-examined in the light of newly developed and developing knowledge of the epithermal model and depositional processes. Examples are expansion of gold production at the Verespatak mine in Transylvania and development of new high-grade silver ore at Fresnillo and Taxeo in Mexico.

Exploration for epithermal deposits in New Mexico is increasing. Notable epithermal deposits of New Mexico and southeast Arizona include Mogollon and the Commonwealth mine in southeast Arizona.