Martha-Brown Cub

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 D-7
Latitude 57.7516
Longitude -136.1991
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Martha-Brown Cub prospect is at an elevation of about 400 feet, about 0.3 mile inland from the east shore of outermost Pinta Bay. The prospect is 0.4 mile south of the northwest corner of sec. 33, T. 47 S., R. 57 E. It is location P-50 of Bittenbender and others (1999) and MAS no. 0021140110 (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 the Freeburn assemblage, a collage of kilometer-scale, fault-bounded, lozenge-shaped blocks of Cretaceous and Cretaceous(?) metasedimentary and metavolcanic rocks. The rocks are cut by high-angle faults that mainly strike northwest.
Bittenbender and others (1999) describe the prospect as a gold-quartz vein in graywacke. There is no information about any workings or 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).
Geologic map unit (-136.200930348522, 57.7512270741005)
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

Indication of production Undetermined

Additional comments

The prospect is in West Chichagof-Yakobi Wilderness.

References

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