Death Valley

Prospect in Alaska, United States with commodity Uranium

Sections on this page

Identification information
Geographic coordinates
Site location context
Geographic areas
Commodities
Materials information
Alteration
Mineral occurrence model information
Host and associated rocks
Nearby scientific data
Economic information about the deposit and operations
Mining district
Links to other databases
Bibliographic references
General comments
Reporter information

Geologic information

Identification information

Deposit ID	10096786
MRDS ID	A012750
Record type	Site
Current site name	Death Valley

Geographic coordinates

Geographic coordinates:	-162.25329, 65.04936 (WGS84)
Relative position	The Death Valley uranium deposit is located in the headwaters of Boulder Creek, a north tributary to the middle Tubutulik River. It is 3.5 miles south of the point where the Tubutulik River leaves Death Valley. The deposit has been explored on the east side of Boulder Creek and the discovery pits are 4,500 feet southeast of Hill 990 and 5,000 feet east of Tubutulik River. This is locality 60 of Gamble (1988).

Geographic coordinates:

-162.25329, 65.04936 (WGS84)

Relative position

The Death Valley uranium deposit is located in the headwaters of Boulder Creek, a north tributary to the middle Tubutulik River. It is 3.5 miles south of the point where the Tubutulik River leaves Death Valley. The deposit has been explored on the east side of Boulder Creek and the discovery pits are 4,500 feet southeast of Hill 990 and 5,000 feet east of Tubutulik River. This is locality 60 of Gamble (1988).

Site location context

Political divisions (FIPS codes)

Nome(Census area)

Alaska(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Bendeleben A-1(quadrangle 1:63,360 scale)

Bendeleben SE(quadrangle 1:100,000 scale)

Bendeleben(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

Norton Bay(hydrologic unit)

Norton Sound(hydrologic accounting unit)

Northwest(hydrologic subregion)

Alaska(hydrologic region)

Federal lands

BLM(Federal land areas administered by BLM)

Geographic areas

Country	State
United States	Alaska

Commodities

Commodity	Importance
Uranium	Primary

Comments on the commodity information

Ore Material = meta-autunite

Materials information

Materials	Type of material
Coffinite	Ore
Sphalerite	Ore
Meta-Autunite	Ore
Pyrite	Gangue

Alteration

(Local) Various clays are developed in the host sedimentary rocks of the epigenetic deposit that may reflect alteration processes. The supergene enrichment accompanies alteration associated with weathering processes.

Mineral occurrence model information

Model code	204
USGS model code	30c
Deposit model name	Sandstone U

Host and associated rocks

Host or associated Host

Rock type

Host or associated	Host
Rock type

Nearby scientific data

(1)	-162.25329, 65.04936	ListMap

Economic information

Comments on the geologic information

Geologic Description = The Death Valley sandstone-type uranium deposit (Dickinson and others, 1987) was discovered in 1977 and soon explored by the Houston International Minerals Corporation. It is in early Eocene continental sediments that are unconformably deposited on deeply weathered granitic rocks of the Darby pluton (Miller and Bunker, 1976; Johnson and others, 1979). The Eocene sediments were deposited in a graben between the uplifted Darby pluton to the west and lower Paleozoic metamorphic rocks to the east (this is probably an onshore, exposed equivalent of the deeper parts of the offshore Norton basin, see below). The proximity to the slightly uraniferous Darby pluton seems to be an important control on the development of this deposit. The continental sediments are conglomerate, arkosic sandstone, mudstone, and coal. The unconformable contact between the coarse, poorly sorted basal sediments and the granitic pluton is gradational and some sediments in this part of the section are interpreted to be mudflows within alluvial systems. The upper part of the sedimentary section contains mudstones deposited in lucustrine environments. Eocene basalt is interbedded with and caps the sedimentary section in this area. These basalts may have created a dam that led to lucustrine sedimentation. The lucustrine mudstones contain laminated siderite but all the sediments compositionally reflect the nearby granitic provenance of the Darby pluton; granitic clasts, quartz, and k-feldspar are common detrital components. Carbonized wood fragments are also common in the section and it contains bituminous coal beds up to 100 feet thick. ? Uranium mineralization is both epigenetic and supergene. Epigenetic mineralization consists of coffinite, small amounts of pyrite, and trace amounts of sphalerite; it extends vertically over a stratigraphic interval of 300 feet both above and below basalt layers. This primary mineralization, interpreted to be early Eocene in age, is formed by the reduction of oxidized groundwaters derived from areas of granitic bedrock by carbonized-wood in conglomerate and arkosic sandstone. The principal mineralized zone defined by drilling covers an area of 395 by 9,850 feet and averages 10 feet in thickness. With an average grade of 0.27 % U3O8, this deposit has a calculated resource of 1,000,000 pounds of U3O8 (Dickinson and others, 1987). The supergene mineralization, related to the present surface, consists of several varieties of meta-autunite in soil and weathered bedrock intervals less than 20 feet thick. The mineralized surficial materials include three zones: (1) a one-foot thick zone of organic-rich clay and sand containing basalt cobbles that may be a debris flow; (2) a zone up to 10-feet thick of arkosic sand containing carbonized wood fragments; and (3) a zone of granitic grus or semiconsolidated arkosic sandstone and mudstone. Some arkosic sandstone fragments contain 11 % U3O8 and some basalt fragments have uraniferous weathering rinds. Epigenetic mineralization is considered to be early Eocene in age, a time when the climate was temperate or subtropical (Dickinson and others, 1987). This is the age of the host sediments and mineralization must have occurred before later Tertiary faulting disrupted groundwater flow eastward from the Darby pluton. The supergene mineralization is Recent in age and may be ongoing today. The Death Valley sandstone-type uranium deposit is the farthest north deposit of its type in the world. At the time of its formation, it was probably at an even higher latitude than it is today, 64 degrees north.
Age = Epigenetic mineralization is considered to be early Eocene in age, a time when the climate was temperate or subtropical (Dickinson and others, 1987). This is the age of the host sediments and mineralization must have occurred before Tertiary faulting disrupted groundwater flowing eastward from the Darby pluton. The supergene mineralization is Recent in age and may be ongoing today.
Age = Host sediments are Early Eocene.

Economic information about the deposit and operations

Development status	Prospect
Commodity type	Metallic

Comments on exploration

Status = Active

Mining district

District name	Koyuk

Comments on the reserve resource information

Reserves = the principal mineralized zone that has been defined by drilling covers an area of 395 by 9,850 feet and averages 10 feet in thickness. This deposit has a calculated resource of 1,000,000 pounds of U3O8 at an average grade of 0.27 % U3O8 (Dickinson and others, 1987). This is the largest presently known uranium deposit in Alaska.

Comments on the workings information

Workings / Exploration = Surface pits, surface mapping, and extensive core drilling have been completed on this deposit.

Reference information

Links to other databases

Agency	Database name	Acronym	Record ID	Notes
USGS	Mineral Resources Data System	MRDS	A012750
USGS	Alaska Resource Data File	ARDF	BN089

Bibliographic references

Deposit

Miller, T.P., and Bunker, C.M., 1976, A reconnaissance study of the uranium and thorium contents of plutonic rocks of the southeastern Seward Peninsula, Alaska: U.S. Geological Survey Journal of Research, v. 4, p. 367-377.
Deposit

Johnson, B.R., Miller, T.P., and Karl, S., 1979, Uranium-thorium investigations of the Darby pluton, Seward Peninsula, Alaska: U.S. Geological Survey Circular 804-B, p. 68-70.
Deposit

Fisher, M.A., Patton, W.W., Jr., and Holmes, M.L., 1982, Geology of Norton Basin and continental shelf beneath northwestern Bering Sea, Alaska: American Association of Petroleum Geologists Bulletin, v. 66, p. 255-285.
Deposit

Dickinson, K.A., Cunningham, K.D., and Ager, T.A, 1987, Geology and origin of the Death Valley uranium deposit, Seward Peninsula, Alaska: Economic Geology, v. 82, p. 1558-1574.
Deposit

Gamble, B.M., 1988, Non-placer mineral occurrences in the Solomon, Bendeleben, and southern part of the Kotzebue quadrangles, western Alaska: U.S. Geological Survey Map MF-1838-B, 13 p., 1 sheet, scale 1:250,000.
Deposit

Worrall, D.M., 1991, Tectonic history of the Bering Sea and the evolution of Tertiary strike-slip basins of the Bering Shelf: Geological Society of America Special Paper 257, 120 p.

Comments on the references

Primary Reference = Dickinson and others, 1987

General comments

Subject category	Comment text
Deposit	Model Name = Sandstone U (Cox and Singer, 1986; model 30c)
Deposit	Other Comments = the prospect is presently controlled by David Hedderly-Smith, P. O. Box 443, Park City, UT 84060. The non-mineralized, early Eocene geology exposed and documented at this prospect may be representative of the basal parts of Tertiary basins elsewhere in the region. This includes the offshore Norton basin to the south of Seward Peninsula that has been explored for its hydrocarbon potential (e. g. Fisher and others, 1982; Worrall, 1991).

Subject category

Comment text

Deposit

Model Name = Sandstone U (Cox and Singer, 1986; model 30c)

Deposit

Other Comments = the prospect is presently controlled by David Hedderly-Smith, P. O. Box 443, Park City, UT 84060. The non-mineralized, early Eocene geology exposed and documented at this prospect may be representative of the basal parts of Tertiary basins elsewhere in the region. This includes the offshore Norton basin to the south of Seward Peninsula that has been explored for its hydrocarbon potential (e. g. Fisher and others, 1982; Worrall, 1991).

Reporter information

Type	Date	Name	Affiliation	Comment
Reporter	15-MAR-1999	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.