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Sea Breeze

Prospect in Alaska, United States with commodities Gold, Lead, Zinc
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Sections on this page
  1. Identification information
  2. Geographic coordinates
  3. Site location context
  4. Geographic areas
  5. Commodities
  6. Materials information
  7. Alteration
  8. Mineral occurrence model information
  9. Host and associated rocks
  10. Nearby scientific data
  11. Economic information about the deposit and operations
  12. Mining district
  13. Links to other databases
  14. Bibliographic references
  15. General comments
  16. Reporter information

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.

Site location context

Political divisions (FIPS codes)

Ketchikan Gateway(Borough)

Alaska(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Ketchikan B-4(quadrangle 1:63,360 scale)

Ketchikan SW(quadrangle 1:100,000 scale)

Ketchikan(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

Ketchikan(hydrologic unit)

Southern Southeast Alaska(hydrologic accounting unit)

Southeast Alaska(hydrologic subregion)

Alaska(hydrologic region)

Federal lands

Tongass National Forest(National Forest)

National Forest FS(Type of land area)

FS(Federal land areas administered by FS)

Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Gold Primary
Lead Secondary
Zinc Critical 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
ListMap

Economic information

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 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

Bibliographic references

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

Beyond USGS

Supplemental information added by qvyshift.com. Not part of the original USGS MRDS record.

Maps centered on this site

Authoritative Alaska resources

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