|Quadrangle map, 1:250,000-scale||MG|
|Quadrangle map, 1:63,360-scale||A-2|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||The Bowser Creek-Headwaters prospect is located in the valley bottom of the headwaters of Bowser Creek; it extends for a distance of about 750 feet (230 meters) at an elevation of 4,400-to-4,500 feet (1,340 to 1,370 meters) in the NE1/4 sec. 5, T. 24 N., R. 24 W., of the Seward Meridian. Location is precisely known; reporter visited the site in 1982.|
The Bowser Creek-Headwaters prospect consists of disseminated to massive, sulfide mineralization in discrete, northwest-trending, steeply dipping, quartz-carbonate veins and vein breccias cutting quartz porphyry of the Bowser Creek composite pluton. The quartz porphyry phase, which has been radiometrically dated a 60.4 Ma; it intrudes the Early to mid-Paleozoic Dillinger subterrane (Bundtzen and others, 1988; Bundtzen, Harris, and Gilbert, 1997). A prospect map has been published by Bundtzen and others (1988).Sulfide minerals include massive sphalerite and pyrrhotite, with lesser amounts of galena, chalcopyrite, and arsenopyrite. Pyrrhotite and arsenopyrite clearly crosscut previously deposited galena, sphalerite, and pyrite. Reed and Elliott (1968, C 559) reported scattered values of up to 4,820 grams/tonne silver, 0.08 grams/tonne gold, 3.00 percent arsenic, 3.00 percent copper, 200 ppm cobalt, 10.00 percent zinc, and 10.00 percent lead. The average of four chip samples taken by Bundtzen and others (1988) across the sulfide-bearing vein system was 35.7 grams/tonne silver, 0.29 percent copper, 0.14 percent lead, and 4.00 percent zinc, but no detectable gold. Other elevated metal concentrations include 469 ppm arsenic, 0.12 percent cadmium, and 169 ppm cobalt (Bundtzen and others, 1988).
|Geologic map unit||(-153.720223517831, 62.1943834118427)|
|Mineral deposit model||Polymetallic vein (Cox and Singer, 1986; model 22c).|
|Mineral deposit model number||22c|
|Age of mineralization||Inferred to be Tertiary, based on a K-Ar age of 60.4 Ma from host quartz porphyry intrusion.|
|Alteration of deposit||Massive pyrrhotite is heavily oxidized to ferricrete gossan.|
|Workings or exploration||No surface exploration excavations have been undertaken at the prospect. Reed and Elliott (1968, C 559) reported scattered values of up to 4,280 grams/tonne silver, 0.08 grams/tonne gold, 3.00 percent arsenic, 3.00 percent copper, 200 ppm cobalt, 10.00 percent zinc, and 10.00 percent lead. The average metallic content of four chip samples taken by Bundtzen and others (1988) across the sulfide-bearing veins was 37.5 grams/tonne silver, 0.29 percent copper, 0.14 percent lead, and 4.00 percent zinc. Other elevated metal concentrations include 469 ppm arsenic, 0.12 percent cadmium, and 169 ppm cobalt noted by Bundtzen and others (1988).|
|Indication of production||None|
Additional commentsPart of a larger mineral center related to the Bowser Creek composite pluton; see Bowser Creek-Main (MG068) and Bowser Creek-Northeast (MG067) prospects.
Bundtzen, T.K., Harris, E.E., and Gilbert, W.G., 1997, Geologic Map of the eastern McGrath quadrangle, Alaska: Alaska Division of Geological and Geophysical Surveys Report of Investigations 97-14, 34 p., 1 sheet, scale 1:125,000.
Bundtzen, T.K., Kline, J.T., Smith, T.E., and Albanese, M.D., 1988, Geology of the McGrath A-2 quadrangle, Alaska: Alaska Division of Geological and Geophysical Surveys Professional Report 91, 18 p., 1sheet, scale 1:63,360.
|Reporters||T.K. Bundtzen (Pacific Rim Geological Consulting)|
|Last report date||10/13/1998|