Unnamed (outlet of Lake Anna)

Prospect, Undetermined

Commodities and mineralogy

Main commodities Au
Ore minerals gold
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale SI
Quadrangle map, 1:63,360-scale C-7
Latitude 57.6246
Longitude -136.0781
Nearby scientific data Find additional scientific data near this location
Location and accuracy This prospect is at sea level on the north side of the passage between Lake Anna and Klag bay. The prospect is 0.4 mile southwest of the northeast corner of sec. 15, T. 49 S., R. 58 E. It is location P-81 of Bittenbender and others (1999), location 40 of Cobb (1972, 1978), and MAS no. 0021140053 (U.S. Bureau of Land Management, 2002). The location is accurate within about 0.2 mile.

Geologic setting

Geologic description

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.
Bittenbender and others (1999), citing Overstreet (1967) and Still and Weir (1981), describe this prospect as a thin quartz vein in graywacke. Samples of the vein contained up to 0.005 ounce of gold per ton. The vein has been explored by an 80-foot adit. There is no record of production.
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). ARDF record SI087 provides an overview of the geology of auriferous quartz veins in the Chichagof Mining District.
Geologic map unit (-136.079920882049, 57.6242305400595)
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).

Production and reserves

Workings or exploration The vein was explored by an 80-foot adit.
Indication of production Undetermined
Production notes There is no record of production.

Additional comments

The prospect is in West Chichagof-Yakobi Wilderness.

References

MRDS Number A013284

References

Bittenbender, P., Still, J.C., Maas, K., and McDonald, M., Jr., 1999, Mineral resources of the Chichagof and Baranof Islands area, southeast Alaska: Bureau of Land Management, BLM-Alaska Technical Report 19, 222 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.
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