Security Cove

Occurrence, Inactive

Commodities and mineralogy

Main commodities Au
Other commodities Pb; Pt
Ore minerals gold; platinum group metal alloys; pyrite

Geographic location

Quadrangle map, 1:250,000-scale HG
Quadrangle map, 1:63,360-scale C-6
Latitude 58.657
Longitude -161.944
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]).

Geologic setting

Geologic description

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.

Production and reserves

Workings or exploration Fechner (1988) reported that minor prospecting pits were locally present in the area.
Indication of production None

References