|Quadrangle map, 1:250,000-scale||MG|
|Quadrangle map, 1:63,360-scale||A-5|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||This unnamed occurrence is located on a north-south ridgeline overlooking an unnamed tributary of Cheeneetnuk River; it is at an elevation of 2,475 feet (754 m) in the SE1/4 sec. 19, T. 23 N., R. 32 W., of the Seward Meridian. The location corresponds to map number 138 in Gilbert (1981); his station no. 77WG203. The reporter visited the site in 1989.|
This unnamed occurrence is a sulfide gossan hosted in Upper Paleozoic argillite of the Mystic subterrane, adjacent to a Tertiary andesite dike (Gilbert, 1981; Wilson and others, 1998). The gossan trends northeast for 90 meters and may be related to the dike.Pyrite impregnates ferricrete gossan in one sample; otherwise sulfide minerals have been completely oxidized. The argillite is locally thermally upgraded to hornfels; axinite and secondary biotite are observed in talus and rubble crop. A mid-Tertiary (39.8 Ma) granite pluton (Solie and others, 1991) is exposed in low angle contact with the Upper Paleozoic argillite and probably underlies the ridge where the mineralization occurs. Surface dimensions of the gossan are not available. One grab sample of gossan contained 350 ppm copper and 0.3 grams/tonne silver (Gilbert, 1981).
|Geologic map unit||(-155.209311418549, 62.0643434095592)|
|Mineral deposit model||Polymetallic replacement? (Cox and Singer, 1986; model 19a?).|
|Mineral deposit model number||19a?|
|Age of mineralization||Unknown; possibly related to 39.8 Ma granite body nearby (Gilbert, 1981; Solie and others, 1991).|
|Alteration of deposit||Axinite, secondary biotite.|
|Workings or exploration||W.G. Gilbert found the occurrence during a geologic mapping program for the Alaska Division of Geological and Geophysical Surveys in 1977 (Gilbert, 1981). One grab sample of gossan contained 350 ppm copper and 0.3 grams/tonne silver (Gilbert, 1981).|
|Indication of production||None|
Gilbert, W.G., 1981, Preliminary geologic map and geochemical data, Cheeneetnuk River area, Alaska: Alaska Division of Geological and Geophysical Surveys Open-File Report 153, 12 p., 2 sheets, 1:63,360 scale.
Solie, D.N., Bundtzen, T.K., and Gilbert, W.G., 1991, K/Ar ages of igneous rocks in the McGrath quadrangle, Alaska: Alaska Division of Geological and Geophysical Surveys Public Data File 91-23, 7 p., 1 sheet, 1:250,000 scale.
|Reporters||T.K. Bundtzen (Pacific Rim Geological Consulting)|
|Last report date||12/10/1998|