Abstract by David Tomlinson
Coupling macro- and microscale observations with geochemical data to determine the depositional controls and origins of fissure ore at the Bingham Canyon mine, Utah.
The Bingham Canyon mine is a porphyry Cu-Au-Mo deposit located in the Oquirrh Mountains of northern Utah centered on an Eocene igneous complex. The mine is expanding its operations to reach deeper reserves along the southern flank of the pit. During this expansion mineralized fissures have been reencountered that have proven to be economic to mine for Cu, Au, and Ag. These fissures vary from the mine-scale down the micron-scale. The variations include textures, structures, and mineralogy that are largely controlled by distance from the center of the deposit and the host rock (monzonite, quartzite, and limestone). Geochemical data from whole rock and minerals support these relationships and can be used to infer the nature of the mineralizing fluids and predict where economic ore will occur. The best fissure Cu, Au, and Ag ore begins 1300 m away from the deposit center; however, this is also where Pb-Zn mineralization begins. This is problematic as those elements have deleterious effects on current processing techniques. The best Au grades are associated with the presence of late-stage tennantite and is most common in monzonite-hosted fissures.