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Shotgun (Mose)

Prospect in Alaska, United States with commodity Gold
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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. Nearby scientific data
  9. Economic information about the deposit and operations
  10. Mining district
  11. Links to other databases
  12. Bibliographic references
  13. General comments
  14. Reporter information

Geologic information

Identification information

Deposit ID 10308357
Record type Site
Current site name Shotgun (Mose)

Geographic coordinates

Geographic coordinates: -158.12275, 60.40935 (WGS84)
Relative position The Shotgun prospect is in the south part of the Shotgun Hills, a rugged. glaciated upland at the divide between the King Salmon and Kogrukluk/Holitna River drainages. The map site is in the NW1/4 of section 27, T 4 N, R 51 W, of the Seward Meridian. It is on the crest and eastern slope of a northwest-trending ridge at an elevation of about 2,575 feet.

Site location context

Political divisions (FIPS codes)

Dillingham(Census area)

Alaska(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Taylor Mountains B-6(quadrangle 1:63,360 scale)

Taylor Mountains SW(quadrangle 1:100,000 scale)

Taylor Mountains(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

Upper Nushagak River(hydrologic unit)

Nushagak River(hydrologic accounting unit)

Southwest(hydrologic subregion)

Alaska(hydrologic region)

Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Gold Primary

Comments on the commodity information

  • Gangue = carbonate

Materials information

Materials Type of material
Arsenopyrite Ore
Tetradymite Ore
Bismuth Ore
Chalcocite Ore
Chalcopyrite Ore
Copper Ore
Covellite Ore
Gold Ore
Marcasite Ore
Pyrite Ore
Pyrrhotite Ore
Scheelite Ore
Sphalerite Ore
Lollingite Ore
Albite Gangue
Quartz Gangue
Sericite Gangue
Tourmaline Gangue

Alteration

  • (Local) Silicification and albite-sericite-quartz +/- carbonate replacement of host intrusive rocks.

Nearby scientific data

(1) -158.12275, 60.40935
ListMap

Economic information

Comments on the geologic information

  • Geologic Description = This prospect was discovered in the 1980s as a result of a regional exploration program by Cominco Alaska in a joint venture with ENSTAR. They named this prospect Mose and completed surface mapping, sampling, and the drilling of six shallow diamond drill holes. In the 1990s, ENSTAR's interest was sold to NovaGold Resources Inc., the prospect was renamed Shotgun, and a renewed exploration effort took place. This exploration included extensive diamond drilling in 1998 that included 19 drill holes totaling 10,170 feet (Novagold Resources Inc., 2000). The Shotgun prospect is an intensely quartz-veined felsic porphyry stock that sharply crosscuts biotite hornfels developed in mid-Cretaceous clastic sedimentary rocks of the Kuskokwim Group (Rombach, 2000). As exposed along the ridge crest and downslope to the east, the stock is an irregularly shaped composite intrusive that is about 1,000 feet long in a northwest direction and over 500 feet long in a northeast direction. The hornfels near the stock and across the ridge crest to the southwest commonly is breccia healed by a toumaline-rich matrix and locally cut by veinlets that contain arsenopyrite, pyrite, and some chalcopyrite. In the stock, some zones near the contact are extensively silicified; quartz replacement is massive and complete in these zones. Elsewhere, the stock is cut by quartz veins that in places form an intense, anastomosing stockwork. Albite-sericite-quartz +/- carbonate replacement of host intrusive rocks accompanies the quartz veining. The deposit is deeply oxidized and iron-staining is widespread. Ore minerals identified at Shotgun include arsenopyrite, primary native gold and bismuth, Bi-Te sulfides, chalcopyrite, lollingite, pyrrhotite, pyrite, scheelite, sphalerite, and supergene covellite, chalcocite, native copper, and marcasite (Rombach, 2000). Vapor-rich and saline-rich fluid inclusions coexist in the quartz veins. The vapor-rich inclusions contain, in order of abundance, water, carbon dioxide, and methane; these inclusions homogenize to vapor at about 360 degrees C. The saline-rich inclusions have salinities of 40 to greater than 60 weight percent NaCl equivalent and homogenize to liquid at 280 to more than 600 degrees C (Rombach, 2000). Surface rock samples define a large geochemical anomaly with several areas where gold values exceed 1 ppm. Examples of drill hole intercepts include 233 feet grading 0.077 ounce of Au per ton, 399 feet grading 0.050 of ounce Au per ton, and 43 feet grading 0.155 ounce of Au per ton (NovaGold Resources Inc., 2000; all drill hole intercepts are listed online at http://www.nrigold.com/shotgun.htm). Preliminary metallurgical tests indicate that gold recoveries of more than 93 percent can be achieved using conventional cyanidation. A resource estimate, using a 0.018 ounce of Au per ton cutoff, is 32,765,000 tons grading 0.033 ounce of Au per ton. The mineralization is open to the north, west, and at depth. Airborne and ground magnetometer surveys have been used in conjuction with extended mapping and sampling to evaluate the potential for additional mineralization in surrounding areas. A large granitic pluton makes up the core of the Shotgun Hills. The contact between this pluton and the hornfels that surrounds the Shotgun prospect coincides with a northwest-trending linear swale and drainage less than 0.5 mile north of the prospect. The shallow-seated intrusive environment south of this contact (extensive hornfels locally cut by fine-grained porphyry) compared to that to the north, suggests that this contact is a large, down-to-the-south fault. K/Ar and Ar/Ar dating of intrusive rocks and mineralization in the Shotgun prospect area indicate that magmatism and mineralization is latest Cretaceous in age, about 68 to 70 Ma (Rombach, 2000; Travis Hudson, unpublished data, 2000).
  • Age = Latest Cretaceous. K/Ar and Ar/Ar dating of intrusive rocks and mineralization in the Shotgun prospect area indicate that magmatism and mineralization is latest Cretaceous in age, about 68 to 70 Ma (Rombach, 2000; Travis Hudson, unpublished data, 2000).

Economic information about the deposit and operations

Development status Prospect

Comments on exploration

  • Status = Active

Mining district

District name Bristol Bay region

Comments on the reserve resource information

  • Reserves = Novagold Resources Inc. (2000) has made the following resource estimates: using a cutoff pf 0.018 ounce of Au per ton, the resource is 32,765,000 tons grading 0.033 ounce of Au per ton; using a cutoff of 0.026 ounce of Au per ton, the resource is 16,550,000 tons grading 0.045 ounce of Au per ton; using a cutoff of 0.035 ounce of Au per ton, the resource is 11,650,000 tons grading 0.05 ounce of gold per ton.

Comments on the workings information

  • Workings / Exploration = This prospect was discovered in the 1980s as a result of a regional exporation program by Cominco Alaska in joint venture with ENSTAR. They named this prospect Mose and completed surface mapping, sampling, and the drilling of six shallow diamond drill holes. In the 1990s, ENSTAR's interest was sold to NovaGold Resources Inc., the prospect was renamed Shotgun, and a renewed exploration effort took place. This exploration included extensive new diamond drilling in 1998 that included 19 drill holes totaling 10,170 feet. Airborne and ground magnetometer surveys have been used in conjuction with extended mapping and sampling to evaluate the potential for additional deposits in surrounding areas.

Reference information

Bibliographic references

  • Deposit

    NovaGold Resources Inc., 2000, Shotgun Project: http://www.nrigold.com/shotgun.htp

  • Deposit

    Rombach, C.S., 2000, Genesis and mineralization of the Shotgun deposit, southwestern Alaska, in The Tintina gold belt: Concepts, exploration, and discoveries: British Columbia and Yukon Chamber of Mines, Special Volume 2, p. 181-196.

Comments on the references

  • Primary Reference = Rombach, 2000

General comments

Subject category Comment text
Deposit Model Name = Gold-bearing quartz-stockwork veining in felsic porphyry

Reporter information

Type Date Name Affiliation Comment
Reporter 30-DEC-00 Travis L. Hudson Applied Geology

Beyond USGS

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

Maps centered on this site

Authoritative Alaska resources

These are landing pages for further research — the state agencies don't currently expose per-mine deep links.