Sea Breeze

Prospect in Alaska, United States with commodities Gold, Lead, Zinc

Geologic information

Identification information

Deposit ID 10001588
MRDS ID A012344
Record type Site
Current site name Sea Breeze

Geographic coordinates

Geographic coordinates: -131.1887, 55.37086 (WGS84)
Relative position The Sea Breeze prospect is at an elevation of about 200 feet, approximately 0.2 mile south-southwest of the mouth of Beaver Lake. The site is in section 18, T. 75 S., R. 94 E., of the Copper River Meridian. It corresponds to loc. 91 in Elliott and others (1978), and to loc. 300 (1-5) in Maas and others (1995). The location is accurate within a few hundred feet.
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Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Gold Primary
Lead Secondary
Zinc Secondary

Materials information

Materials Type of material
Galena Ore
Gold Ore
Pyrite Ore
Sphalerite Ore
Quartz Gangue

Alteration

  • (Local) The walls of some of the veins are bluish-gray, hydrothermally altered rock that was interpreted by the early miners as a dike, or dikes, of intrusive porphyry ('blue porphyry' of Brooks, 1902, p. 65-67; and Wright and Wright, 1908, p. 144-146). Maas and others (1995, p. 215), however, interpret it as a zone of hydrothermally altered mafic metavolcanic rock.

Mineral occurrence model information

Model code 273
USGS model code 36a
Deposit model name Low-sulfide Au-quartz vein
Mark3 model number 27

Host and associated rocks

  • Host or associated Host
    Rock type Metamorphic Rock > Metavolcanic Rock > Mafic Metamorphic Rock > Greenstone

Nearby scientific data

(1) -131.1887, 55.37086

Comments on the geologic information

  • 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 (in press) 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 Sea Breeze claim adjoins the Sea Level claim (KC095) on the northeast, and is located on the extension of its mineralized belt (Brooks, 1902, p. 67; Wright and Wright, 1908, p. 146; Maas and others, 1995, fig. 55). The deposit consists of quartz fissure veins 1-8 feet thick in mafic metavolcanic (greenstone) country rock. The veins strike NE and dip steeply SE, and are sharply discordant to the NW foliation of the metavolcanic country rocks. The veins are characterized by intense fracturing, brecciation, and abrupt variations in mineralization. The ore minerals include [auriferous] pyrite, galena, sphalerite, and an occasional speck of native gold. Auriferous pyrite also is sparsely disseminated in the wallrocks adjacent to the veins (Maas and others, 1995, p. 215). The walls of some of the veins are bluish-gray, hydrothermally altered rock that was interpreted by the early miners as a dike, or dikes, of intrusive porphyry ('blue porphyry' of Brooks, 1902, p. 65-67; and Wright and Wright, 1908, p. 144-146). Maas and others (1995, p. 215), however, interpret it as a zone of hydrothermally altered mafic metavolcanic rock.? Maas and others (1995) also report that the quartz in the veins is not recrystallized. The veins thus probably are younger than most or all of the Late Cretaceous regional metamorphism, but are older than a period of intense local faulting and brecciation.? the prospect was explored in the early 1900s by two short tunnels, and by numerous opencuts that exposed the veins for several hundred feet along strike. Maas and others (1995, p. 218) report two adits, one 69 feet long, and one caved. Maas and others (1995, p. 217-218) report a mean value of 661 ppb Au in 12 samples of the Sea Breeze vein. Their best assay showed 2.0 ppm Au in an 8.5-foot sample across the vein.
  • Age = Maas and others (1995) report that the quartz in the veins is not recrystallized. The veins thus probably are younger than most or all of the Late Cretaceous regional metamorphism, but are older than a period of intense local faulting and brecciation.

Economic information

Economic information about the deposit and operations

Development status Prospect
Commodity type Metallic

Mining district

District name Ketchikan

Comments on the workings information

  • Workings / Exploration = The prospect was explored in the early 1900s by two short tunnels, and by numerous opencuts that exposed the veins for several hundred feet along strike. Maas and others (1995, p. 218) report two adits, one 69 feet long, and one caved. Maas and others (1995, p. 217-218) report a mean value of 661 ppb Au in 12 samples of the Sea Breeze vein. Their best assay showed 2.0 ppm Au in an 8.5-foot sample across the vein.

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Mineral Resources Data System MRDS A012344
USGS Alaska Resource Data File ARDF KC094

Bibliographic references

  • Deposit

    Brooks, A.H., 1902, Preliminary report on the Ketchikan mining district, Alaska, with an introductory sketch of the geology of southeastern Alaska: U.S. Geological Survey Professional Paper 1, 120 p.

  • Deposit

    Wright, F.E., and Wright, C.W., 1908, The Ketchikan and Wrangell mining districts, Alaska: U.S. Geological Survey Bulletin 347, 210 p.

  • Deposit

    Elliott, R.L., Berg, H.C., and Karl, Susan, 1978, map and table describing metalliferous and selected nonmetalliferous mineral deposits, Ketchikan and Prince Rupert quadrangles, Alaska: U.S. Geological Survey Open-file Report, 78-73-B,17 p., scale 1:250,000.

  • Deposit

    Berg, H.C., 1982, The Alaska Mineral Resource Assessment Program; guide to information about the geology and mineral resources of the Ketchikan and Prince Rupert quadrangles, southeastern Alaska: U.S. Geological Survey Circular 855, 24 p.

  • Deposit

    Berg, H.C., Elliott, R.L., and Koch, R.D., 1988, Geologic map of the Ketchikan and Prince Rupert quadrangles, southeastern Alaska: U.S. Geological Survey Mineral Investigations Series Map MF-1807,27 p., scale 1:250,000.

  • Deposit

    Maas, K.M., Bittenbender, P E., and Still, J.C., 1995, Mineral investigations in the Ketchikan mining district, southeastern Alaska: U.S. Bureau of Mines Open-File Report 11-95, 606 p.

  • Deposit

    Crawford, M.L., Crawford, W.A., and Gehrels, G.E., 2000, Terrane assembly and structural relationships in the eastern Prince Rupert quadrangle, British Columbia, in H.H. Stowell and W.C.McClelland, eds., Tectonics of the Coast Mountains, southeastern Alaska and British Columbia: Boulder, Colorado, Geological Society of America Special Paper 343, p. 1-21.?

Comments on the references

  • Primary Reference = Brooks, 1902; Maas and others, 1995

General comments

Subject category Comment text
Deposit Model Name = Low-sulfide Au-quartz veins (Cox and Singer, 1986; model 36a)

Reporter information

Type Date Name Affiliation Comment
Reporter 04-JUL-1999 H.C. Berg U.S. Geological Survey