|Quadrangle map, 1:250,000-scale||HG|
|Quadrangle map, 1:63,360-scale||C-6|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||Security Cove is on the north side of the peninsula between Kuskokwim Bay and Hagemeister Strait. This occurrence is on the west side of Security Cove, approximately 8 miles east of Cape Newenham and 2 miles north of the summit of Gap Mountain. The location is probably accurate within 0.25 mile. It is locality 3 of Cobb (1972 [MF 362]; 1980 [OF 80-909]).|
On 6/1/72, Allen L. Clark (U. S. G. S.) reported to E. H. Cobb that lode gold had been found in this area (Cobb (1972 [MF 362]; 1980 [OF 80-909]). The area is underlain by low-grade metasedimentary and metavolcanic rocks, including schistose calcareous siltstone and limestone, and greenish tuffaceous rocks (Hoare and Coonrad, 1978). These rocks are part of a regional assemblage (Goodnews terrane of Kilburn and others, 1993, and Decker and others, 1994) of sedimentary and volcanic rocks that ranges in age from Devonian to Jurassic. On the peninsula that includes Security Cove, the metasedimentary and metavolcanic rocks are intruded by small, Jurassic (?) ultramafic plutons (Hoare and Coonrad, 1978). Large parts of this peninsula, including areas around Security Cove, are covered by Quaternary gravel deposits.Fechner (1988) reported stream-sediment, beach-, and rock-sample data for the Security Cove area. The stream sediments contained up to 0.0033 ounce of gold per cubic yard and beach samples contained trace amounts of gold. One third of the gold in the stream sediments was + 20 mesh in size and rough and iron-stained. Three PGM grains were found in one sample. The bedrock outcrops along the west side of Security Cove are metavolcanic and argillaceous rocks cut by 4- to 15-foot-wide shear zones that strike N 45-55 E and dip 60 to 75 degrees south. The shear zones contain abundant pods of pyrite; one bedrock sample (no. 253, Fechner, 1988) contained 3,460 ppm lead, but gold was below detection limits (5 ppb).
|Geologic map unit||(-161.946222440466, 58.656209342624)|
|Mineral deposit model||Placer Au-PGE (Cox and Singer, 1986; model 39a). Unclassified lodes in shear zones.|
|Mineral deposit model number||39a|
|Age of mineralization||The placer occurrences that have been sampled are Holocene. The bedrock mineralization in shear zones that cut the low-grade metasedimentary rocks is probably post-Jurassic, the age of the younger sedimentary rocks in the regional Goodnews terrane (Decker and others, 1994).|
|Alteration of deposit||Oxidation and iron-staining is locally present.|
|Workings or exploration||Fechner (1988) reported that minor prospecting pits were locally present in the area.|
|Indication of production||None|
Cobb, E.H., 1972, Metallic mineral resources map of the Hagemeister Island quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-362, 1 sheet, scale 1:250,000.
Cobb, E.H., 1980, Summaries of data and lists of references to metallic and selected nonmetallic mineral deposits in fifteen quadrangles in southwestern and west-central Alaska: U.S. Geological Survey Open-File Report 80-909, 103 p.
Decker, J., Bergman, S.C., Blodgett, R.B., Box, S.E., Bundtzen, T.K., Clough, J.G., Coonrad, W.L., Gilbert, W.G., Miller, M.L., Murphy, J.M., Robinson, M.S., and Wallace, W.K., 1994, Geology of southwestern Alaska, in Plafker, G. and Berg, H.C., eds., The Geology of Alaska: Geological Society of America DNAG, The Geology of North America, v. G-1, p. 285-310.
Fechner, S.A., 1988, Bureau of Mines mineral investigation of the Goodnews Bay mining district, Alaska: U.S. Bureau of Mines Open-File Report 1-88, 230 p., 3 sheets.
Kilburn, J., Box, S.E., Goldfarb, R.J., and Gray, J.E., 1992, Geochemically anomalous areas in the eastern Goodnews Bay 1 degre x 3 degree quadrangle, southwest Alaska, in Bradley, D.C., and Ford, A.B., eds., Geologic studies by the U.S. Geological Survey in 1990: U.S. Geological Survey Bulletin 1999, p. 156-162.
|Reporters||Travis L. Hudson|
|Last report date||3/18/2001|