|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-Northeast prospect is located on a steep, north-trending spur on the north side of Bowser Creek valley; it is at an elevation of 4,700 feet to 5,100 feet (1,432 to 1,554 meters) in sec. 4, T. 24 N., R. 24 W., of the Seward Meridian. The prospect is precisely known; the reporter visited the site in 1982.|
The Bowser Creek-Northeast prospect is a north-trending, elongate mineral zone that averages 7 meters wide and about 300 meters long near a small body of quartz porphyry and related felsite dikes, which are satellite intrusions of the main Bowser Creek composite pluton (Bundtzen and others, 1988). The plutonic rocks intrude a limestone-rich section of the Dillinger subterrane (Bundtzen, Harris, and Gilbert, 1997); host rocks at the Bowser Creek Northeast prospect are Late Silurian to Lower Devonian in age. A prospect map was published by Reed and Elliott (1968, C 559).
According to Reed and Elliott (1968, C 559), the skarn typically consists of pyrrhotite and marmatite (iron-rich sphalerite) with abundant epidote, chlorite, clinopyroxene (hedenbergite), and quartz. Disseminated galena occurs in shear zones related to dike swarm activity.Reed and Elliott (1968, C 559) reported values from chip sample traverses as high as 357.7 grams/tonne silver, 3.4 grams/ton gold, 2.44 percent copper, 24.00 percent lead, and 22.10 percent zinc. According to Bundtzen and others (1988), the average metallic content of several 5 meter chip samples taken across the the mineralized zone was 0.35 grams/tonne gold, 244.0 grams/tonne silver, 821 ppm copper, 12.13 percent lead, and 11.13 percent zinc.
|Geologic map unit||(-153.69222407161, 62.1903840055522)|
|Mineral deposit model||Lead-zinc skarn (Cox and Singer, 1986; model 18c).|
|Mineral deposit model number||18c|
|Age of mineralization||Inferred to be Tertiary, based on a 60.4 Ma K-Ar age from quartz porphyry in the Bowser Creek pluton.|
|Alteration of deposit||Extensive ferricrete oxidation of pyrrhotite and marmatite-rich sulfide zones.|
|Workings or exploration||
The Bowser Creek-Northeast prospect was found by the late Bruce Reed during minerals investigations for the U.S. Geological Survey in the 1960s (Reed and Elliott, 1968, C 596). Reed and Elliott (1968, C 559) reported values from chip sample traverses as high as 357.7 grams/tonne silver, 3.4 grams/tonne gold, 2.44 percent copper, 24.00 percent lead, and 22.10 percent zinc. According to Bundtzen and others (1988), the average metallic content of several 5 meter chip samples taken across the mineralized zone was 0.35 grams/tonne gold, 244.0 grams/tonne silver, 821 ppm copper, 12.13 percent lead, and 11.13 percent zinc.No surface trenching or drilling have been conducted on the property.
|Indication of production||None|
Additional commentsPart of a series of low temperature zinc-lead-silver skarns associated with Bowser Creek composite pluton (see MG066, MG068 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.
Cobb, E.H., 1972, Metallic mineral resources map of the McGrath quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-379, 1 sheet, 1:250,000 scale.
Cobb, E.H., 1976, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Iliamna, Lake Clark, Lime Hills, and McGrath quadrangles, Alaska: U.S. Geological Survey Open-File Report 76-485, 101 p.
Reed, B.L. and Elliott, R.L., 1968, Geochemical anomalies and metalliferous deposits between Windy Fork and Post River, southern Alaska: U.S. Geological Survey Circular 569, 22 pages.
|Reporters||T.K. Bundtzen (Pacific Rim Geological Consulting)|
|Last report date||10/13/1998|