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Crooked Creek

Past Producer in Alaska, United States with commodities Gold, Diamond
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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. Mineral occurrence model information
  8. Host and associated rocks
  9. Nearby scientific data
  10. Economic information about the deposit and operations
  11. Mining district
  12. Links to other databases
  13. Bibliographic references
  14. General comments
  15. Reporter information

Geologic information

Identification information

Deposit ID 10001480
MRDS ID A012229
Record type Site
Current site name Crooked Creek
Related records 10208910

Geographic coordinates

Geographic coordinates: -145.031, 65.5728 (WGS84)
Relative position The location is at the mouth of Sawpit Creek, where mining took place in 1981. Mining in 1952 and 1973 to 1981 was near the mouth of Mammoth Creek and east for several km. Crooked Creek is the drainage below the junction of Porcupine and Mammoth Creeks. It flows 30 km in an easterly direction through the town of Central before joining Birch Creek. The Steese Highway parallels Crooked Creek between the Hot Springs Fault and the town of Central. Placer mining has been confined to the 8 km of the creek immediately downstream from where the Hot Springs fault crosses Crooked Creek (Yeend, 1991, p. 17).

Site location context

Political divisions (FIPS codes)

Yukon-Koyukuk(Census area)

Alaska(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Circle C-3(quadrangle 1:63,360 scale)

Circle NE(quadrangle 1:100,000 scale)

Circle C(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

Alaska(hydrologic region)

Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Gold Primary
Diamond Secondary

Materials information

Materials Type of material
Diamond Ore
Gold Ore

Mineral occurrence model information

Model code 119
USGS model code 39a
Deposit model name Placer Au-PGE
Mark3 model number 54

Host and associated rocks

  • Host or associated Host
    Rock type Unconsolidated Deposit > Gravel
  • Host or associated Host
    Rock type Sedimentary Rock > Clastic Sedimentary Rock > Conglomerate

Nearby scientific data

(1) -145.031, 65.5728
ListMap

Economic information

Comments on the geologic information

  • Geologic Description = Quartzitic schist is present upstream from the Hot Springs fault and along the upstream tributaries, and it makes up most of the detritus in the creek gravel. A small granite outcrop is present upstream along Mammoth Creek (Lampright, 1996). All but this uppermost part of the creek lies within the Tintina fault zone. At the Hot Springs Fault junction the Crooked Creek flood plain dissects late Pleistocene fan gravel that forms a prominent 20 meter high bench to the north. To the south, several less prominent stair-stepped bench levels of late Pleistocene fan gravel grade down to the Crooked Creek flood plain. The alluvial gravel in Crooked Creek is composed predominantly of well-rounded to subrounded clasts as much as 15 cm in diameter. A pebble count in Crooked Creek approximately 4 kilometers downstream from the Hot Springs fault reveals a composition of 43 percent quartz-mica schist, 32 percent quartzite, 21 percent quartz, and 4 percent weathered granite (Yeend, 1991). ? Gold-bearing gravel that is 2 to 5 meters thick overlies false bedrock with clay-rich, altered cobble gravel. Mining excavations in the area where the Hot Springs fault crosses the Crooked Creek valley exposed fault gouge, altered schist bedrock, and orange gravel. Locally, where river scour has eroded the intervening gray gravel, the overlying muck rests directly on the orange gravel (Yeend, 1991, p. 19). Downstream from the Hot Springs fault are many locations where the gray gravel extends vertically into the orange gravel. Gray gravel locations within the orange gravel are interpreted as former sites of ice wedges (Kline, 1985). The gray gravel was able to fill in as the ice wedges melted and the creek washed over the uneven surface (Lampright, 1996).? the gold is thought to be contained within the gray gravel that overlies the clay-rich orange gravel. Some gold extends into the upper orange gravel, but for the most part the orange gravel acts as a trap for the fine gold. ?Placer gold occurs primarily in the lower 1 to 2 meters of gray alluvial gravel, which is generally more consolidated that the overlying gravel and sometimes includes blocks of the underlying orange gravel (Yeend, 1991). The paystreak in Crooked Creek is as much as 400 meters wide and 1 to 2 meters thick (Yeend, 1991). Wood fragments are scattered through the gold bearing gravel. The upper gravel unit yielded an age from wood of approximately 1,480 B.P. This young age implies a continuous reworking of these gravels (Yeend, 1991).? Gold flakes are very flattened, commonly 1 to 3 mm in largest dimension. (Menzie, 1983) Values range from 0.01 to 0.03 ounces per cubic yard. Upstream from the fault, the values are lower, approximately 0.00625 ounces per cubic yard, as reported by miners on the basis of exploratory sampling (Lampright, 1996). ? Placer mining has been confined to the 8 km of the creek immediately downstream from where the Hot Springs fault crosses Crooked Creek (Yeend, 1991, p. 17). Placer mining occurred in 1952 and from 1973 through the 1980's. Bob Cacy of Points North conducted geochemical and magnetic surveys on Crooked Creek in 1993 and 1994 (Bundtzen and others, 1993; Swainbank and others, 1994). ? the first diamonds in the Circle Quadrangle were discovered on Crooked Creek. In 1982, Jim Regan discovered a 0.3 ct diamond in a sluice box. Frank Warren discovered an even larger, 1.4 ct diamond, during placer mining in 1984 (Eakins and others, 1985). In 1986, Paul Manuel recovered a third diamond from the Crooked Creek gravels about 1500 ft downstream from the Warren discovery (Forbes and others, 1987, p. 7). Subsequent investigations by experienced diamond producers indicated no trace minerals indicative of kimberlite or lamproite source rocks.

Economic information about the deposit and operations

Development status Past Producer
Commodity type Metallic

Comments on exploration

  • Status = Inactive

Mining district

District name Circle

Comments on the production information

  • Production Notes = Values range from 0.01 to 0.03 ounces of gold per cubic yard. Upstream from the fault, the values are lower, approximately 0.00625 ounces per cubic yard, as reported by miners on the basis of exploratory sampling (Lampright, 1996). Total amount of production is unknown.

Comments on the workings information

  • Workings / Exploration = Placer mining has been confined to the 8 km of the creek immediately downstream from where the Hot Springs fault crosses Crooked Creek (Yeend, 1991, p. 17). Placer mining occurred in 1952 and from 1973 through the 1980's. Bob Cacy of Points North conducted geochemical and magnetic surveys on Crooked Creek in 1993 and 1994 (Bundtzen and others, 1993; Swainbank and others, 1994).? the first diamonds in the Circle Quadrangle were discovered on Crooked Creek. In 1982, Jim Regan discovered a 0.3 ct diamond in a sluice box. Frank Warren discovered an even larger, 1.4 ct diamond, during placer mining in 1984 (Eakins and others, 1985). Subsequent exploration specifically designed to recover diamonds has been unsuccessful.

Reference information

Bibliographic references

Comments on the references

  • Primary Reference = Yeend, 1991.

General comments

Subject category Comment text
Deposit Model Name = Placer gold deposit (Cox and Singer, 1986; model 39a)
Deposit Other Comments = First placer diamonds documented in Alaska were found on Crooked Creek.

Reporter information

Type Date Name Affiliation Comment
Reporter 08-SEP-98 C.J. Freeman Avalon Development Corporation
Reporter 08-SEP-98 J.R. Guidetti Schaefer Avalon Development Corporation
Reporter 08-SEP-98 Clements, A.S. Avalon Development Corporation

Beyond USGS

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

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Authoritative Alaska resources

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