Lake

Prospect, Undetermined

Commodities and mineralogy

Main commodities Pb; Zn
Ore minerals galena; pyrite; sphalerite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale KC
Quadrangle map, 1:63,360-scale B-4
Latitude 55.409
Longitude -131.195
Nearby scientific data Find additional scientific data near this location
Location and accuracy
The Lake prospect is at an elevation of about 200 feet on Fish Creek, about 0.1 mile above the junction of Silver Creek. The site is in section 31, T. 74 S., R. 94 E., of the Copper River Meridian. It corresponds to loc. 84 in Elliott and others (1978). The location is accurate within 0.1 mile.
Also see Additional comments.

Geologic setting

Geologic description

The country rocks in this part of Revillagigedo Island are marine, interbedded, andesitic and basaltic metavolcanic rocks and subordinate pelitic metasedimentary rocks that are intruded by stocks, sills, and dikes of Cretaceous feldspar-porphyritic granodiorite (Berg and others, 1988). The strata and some of the granodiorite were regionally metamorphosed to greenschist grade in Late Cretaceous time. These regionally metamorphosed rocks subsequently were locally remetamorphosed to hornblende hornfels near the contacts of Cretaceous granodiorite plutons that were emplaced after the regional metamorphism. The premetamorphic age of the strata is uncertain. Berg and others (1988) assign them a Mesozoic or (late) Paleozoic age. Berg (1982) and Crawford and others (2000) assign them to the Gravina belt, of Late Jurassic or Cretaceous age, or to the Taku terrane, of late Paleozoic to Late Triassic age. The metamorphic and intrusive rocks locally are overlain by basalt and andesite lava flows of Quaternary or Tertiary age.
The deposit consists of sulfide-bearing quartz fissure veins in intercalated metapelitic and metavolcanic (greenstone) schists near the contact of a granodiorite pluton (Wright and Wright, 1908, p. 149). The sulfide minerals are pyrite, galena, and sphalerite, generally in small amounts. The largest vein reportedly is up to 60 feet wide; it strikes N15W and dips vertically, across the foliation of the schists.
Geologic map unit (-131.196694784805, 55.4086588654428)
Mineral deposit model Polymetallic veins (Cox and Singer, 1986; model 22c)
Mineral deposit model number 22c
Age of mineralization Late Cretaceous or younger.

Production and reserves

Indication of production None

Additional comments

Wright and Wright refer to this property as 'Lake claims nos. 1, 2, and 3.'
The site is at the boundary of, or within, Misty Fiords National Monument Wilderness.

References