|Quadrangle map, 1:250,000-scale||SI|
|Quadrangle map, 1:63,360-scale||C-7|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||This prospect is at sea level on the northwest shore of Lake Anna about 0.6 mile from the outlet of the lake. Reed and Coats (1941) describe it as the southernmost Woll prospect on the Lucky Shot Group; the U.S. Bureau of Land Management (2002) calls it the Somehow prospect. The prospect is 0.4 mile south of the center of sec. 11, T.49 S., R. 58 E. It is location 40 of Cobb (1972, 1978) and MAS no. 0021140121 (U.S. Bureau of Land Management, 2002). The location is accurate within 0.2 mile.|
Johnson and Karl (1985) map the rocks in the area of this prospect as Cretaceous graywacke and argillite interbedded with sparse, lenticular beds of basalt. The rocks are cut by numerous high-angle, mainly northwest-striking faults; they include the extension of the fault at the Chichagof Mine (SI093), whose trace is about a mile northeast of the prospect.
Reed and Coats (1941) describe this prospect as a 12-foot tunnel driven northwest along a fault that follows the hanging wall of a partly silicified dike about 10 feet thick. The country rock is chiefly massive graywacke that strikes about N35W and dips 65SW. Arsenopyrite and pyrite, with quartz and calcite are in the dike, mainly near its hanging wall, and some sulfides with quartz are in the graywacke of the hanging wall. Reed and Coats (1941) report post-mineralization faulting, and that much of the mineralization appears to be controlled by joints in the dike. There are no assay data or any records of production.Isotopic studies indicate that the gold-quartz veins in coastal southern and southeastern Alaska are Eocene, about 50 Ma in age (Haeussler, 1995; Goldfarb, 1997; Goldfarb and others, 1997). ARDF record SI087 provides an overview of the geology of auriferous quartz veins in the Chichagof Mining District.
|Geologic map unit||(-136.066520864034, 57.629230910011)|
|Mineral deposit model||Low-sulfide gold-quartz vein (Cox and Singer, 1986; model 36a).|
|Mineral deposit model number||36a|
|Age of mineralization||Isotopic studies indicate that the gold-quartz veins in coastal southern and southeastern Alaska are Eocene, about 50 Ma in age (Haeussler and others, 1995; Goldfarb, 1997; Goldfarb and others, 1997).|
|Alteration of deposit||Dike is partly silicified.|
|Workings or exploration||Workings include a 12-foot tunnel.|
|Indication of production||Undetermined|
|Production notes||There are no assay data or any records of production.|
Additional commentsThe prospect is in West Chichagof-Yakobi Wilderness.
Cobb, E.H., 1972, Metallic mineral resources map of the Sitka quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-467, scale 1:250,000.
Cobb, E.H., 1978, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Sitka quadrangle: U.S. Geological Survey Open-File Report 78-450, 124 p.
Goldfarb, R J., 1997, Metallogenic evolution of Alaska, in Goldfarb, R.J., and Miller, L.D., eds., Mineral Deposits of Alaska: Economic Geology Monograph 9, p. 4-34.
Goldfarb, R.J., Miller, L.D., Leach, D.L., and Snee, L.W, 1997, Gold deposits in metamorphic rocks in Alaska, in Goldfarb, R.J., and Miller, L.D., eds., Mineral Deposits of Alaska: Economic Geology Monograph 9, p. 151-190.
Haeussler, P J., Bradley, D., Goldfarb, R., Snee, L., and Taylor, C., 1995, Link between ridge subduction and gold mineralization in southern Alaska: Geology, v. 23, no. 11, p. 995-998.
Reed, J.C., and Coats, R.R., 1941, Geology and ore deposits of the Chichagof mining district, Alaska: U.S. Geological Survey Bulletin 929, 148 p.
Roehm, J.C., 1936, Preliminary report of Mike Woll prospect, Lake Ann, west coast Chichagof Island, Sitka Mining District, Alaska, July 7, 1936: Alaska Territorial Department of Mines, Property Examination 114-5, 1 p.
U.S. Bureau of Land Management, 2002, Alaska mineral locations database report (Sitka quadrangle), July 2, 2002, 205 p. [http://imcg.wr.usgs.gov/dem.html]
|Reporters||H.C. Berg (U.S. Geological Survey)|
|Last report date||10/16/2004|