Geologic descriptionIn the area of the Banner prospect, the northeast-trending Banner fault separates unaltered Triassic sedimentary rocks on the southeast from strongly altered Triassic conglomerate, hornfels, and marble on the northwest. The altered rocks are cut by skarn zones extending 500 feet from the fault zone. The deposit consists of sulfide-bearing skarn and quartz-sericite veins that cut the skarn. Sulfides in the skarn zones vary in content, but average about 10%. They consist of arsenopyrite, pyrrhotite, pyrite, chalcopyrite (unpublished report by Addwest Minerals International Ltd., 1997). Copper content ranges up to 1% and gold values run 0.4 to 1 ounce per ton. The Banner skarn deposit probably is related to an apophysis of the Upper Cretaceous (70-65 Ma) porphyry plug at the Golden Zone mine (HE043). |
Geologic map unit |
(-149.622291655305, 63.2315268935454) |
Mineral deposit model |
Cu skarn and polymetallic veins (Cox and Singer, 1986; models 18b, 22c) |
Mineral deposit model number |
18b, 22c |
Age of mineralization |
The skarns are probably related to an apophysis of the Upper Cretaceous (70-65 Ma) porphyry plug at the Golden Zone mine (HE043). The quartz-sericite veins may be Tertiary. |
Alteration of deposit |
Pyrite-quartz-sericite veins overprint earlier skarn calc-silicate assemblages that consist of epidote, pyroxene, actinolite, and occasional garnet. |