Double Glacier

Occurrence in Alaska, United States with commodities Gold, Copper, Zinc

Geologic information

Identification information

Deposit ID 10307711
Record type Site
Current site name Double Glacier

Geographic coordinates

Geographic coordinates: -152.97863, 60.09245 (WGS84)
Relative position This occurrence is located near the mouth of Double Glacier in section 13, T. 1 S., R. 22 W., of the Seward Meridian. The occurrence is at an elevation of about 1,000 feet.
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Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Gold Primary
Copper Primary
Zinc Primary

Materials information

Materials Type of material
Gold Ore
Pyrite Ore
Sphalerite Ore
Barite Gangue
Calcite Gangue
Gypsum Gangue
Quartz Gangue

Alteration

  • (Local) The Double Glacier occurence has alteration characteristics of a Kuroko type massive sulfide deposit that include sulfate alteration and silification.

Mineral occurrence model information

Model code 184
USGS model code 28a
Deposit model name Massive sulfide, kuroko
Mark3 model number 93

Nearby scientific data

(1) -152.97863, 60.09245

Comments on the geologic information

  • Geologic Description = The Double Glacier occurrence is within the lower Jurassic Talkeetna Formation, an approximately 2,575 meter thick sequence of volcanic and volcaniclastic rocks (Determan and Hartsock, 1966). The volcanic section near the prospect is structurally bounded on the west by the Bruin Bay Fault, a major fault system traceable for over 500 kilometers. On the east, the volcanics are unconformably overlain by upper Jurassic marine sediments (Determan and Hartsock, 1965). The Talkeetna Formation is intruded by rocks of the Aleutian range -Talkeetna Mountain plutonic belt approximately 23 km. southwest of the prospect. These intrusives which consist dominantly of coarse-grained quartz diorites and quartz monzonites have been dated between 175 and 145 m.y. ( Steefel, 1987). . At the Double Glacier occurrence, the Talkeetna Formation has been divided into three major groups (Steefel, 1987). The lowest group consist of purple and green andesite flows and breccia which locally show well-developed pillows. The middle group that host the mineralization, consists of coarse-grain felsic breccias, reworked volcaniclastic rocks, crystal tuff, and dacite flows. The upper group consist of polymitic andesitic breccias and conglomerates with andesitic flows. Informally, the middle group has been named the Johnson unit (Steefel, 1987). Numerous structures within the unit including turbidites and reverse graded bedding indicate a subaqueous origin. . The mineralization consists of strataform massive sulfide layers and lens which contain pyrite, chalcopyrite, and sphalerite. There are no published assay results for this occurrence William Ellis (personal communcation, 1999) speculates that this occurrence is an upper portion of a Kuroko type massive sulfide deposit.
  • Age = Jurassic massive sulfide.

Economic information

Economic information about the deposit and operations

Development status Occurrence

Comments on exploration

  • Status = Inactive

Mining district

District name Reboubt

Comments on the workings information

  • Workings / Exploration = The occurence was discovered by Anaconda Minerals in 1982 as part of an exploration program at the Johnson River prospect. To date there has been detailed mapping, stream and soil geochemical surveys, and surface trenching and sampling. No assay results are avaible.

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Alaska Resource Data File ARDF KN007

Bibliographic references

  • Deposit

    Steefel, C.I., 1987, The Johnson River Prospect, Alaska: Gold rich sea-floor mineralization from the Jurassic: Economic Geology, V. 82, p. 894-914.

  • Deposit

    Swainbank, R.C., Bundtzen, T. K., Clough A.H., and Henning, M.W., 1997, Alaska's mineral industry 1996: Alaska Division of Geological and Geophysical Surveys Special Report 51, 68 p.

General comments

Subject category Comment text
Deposit Model Name = Kuroko massive sulfide (Cox and Singer, 1986; model 28a)
Deposit Other Comments = This occurrence is owned by Cook Region Native Association.

Reporter information

Type Date Name Affiliation Comment
Reporter 15-APR-99 Jeff A. Huber U.S. Geological Survey