Kelly Creek

Prospect, Active

Commodities and mineralogy

Main commodities Au
Other commodities Ag; As; Hg; Sb
Ore minerals arsenopyrite; gold; pyrite
Gangue minerals calcite; quartz

Geographic location

Quadrangle map, 1:250,000-scale TE
Quadrangle map, 1:63,360-scale D-2
Latitude 65.7706
Longitude -165.8962
Nearby scientific data Find additional scientific data near this location
Location and accuracy Kelly Creek, unofficially named in 1982 after film actress Grace Kelly, is a north tributary to the American River. Kelly Creek is the largest tributary entering from the north in the area where the direction of American River changes from north to south. The prospect is about 14.3 miles southeast of Ear Mountain. The 2011 drilling by Cedar Mountain Exploration and the earlier drilling by Anaconda Minerals was 1) aligned northwest to both sides of the saddle centered about 0.5 mile southwest of section 2, T. 4 N., R. 35 W., and 2) in a area about 0.5 mile to the northwest. The location is accurate.

Geologic setting

Geologic description

The Kelly Creek prospect is in mica-quartz schist and graphitic quartz schist intercalated in a metasedimentary sequence that includes schistose, micaceous, dolomitic marble; mica-calcite schist; and minor micaceous quartzite (Cedar Mountain, 2011 [project]). The sequence is interpreted as a limestone-shale assemblage with facies variations. It is highly deformed and perhaps isoclinally folded. Schistosity dips moderately in various directions. Steeply-dipping marble-schist contacts and other strong linear features may indicate normal faults. In the headwaters of Fox Creek, 3 miles north of the Kelly Creek prospect, the rocks consist of a mafic to intermediate(?) metavolcanic and metasedimentary assemblage which consist of various greenschist and amphibolite units regionally intercalated with some calcareous quartzite and marble. The relation of the metavolcanic assemblage to the pelitic schist/marble assemblage that hosts the Kelly Creek prospect is not known. All of the metavolcanic and metasedimentary rocks in area were probably Paleozoic originally and have been metamorphosed in the Cretaceous; Sainsbury (1972) however mapped them as Precambrian.
The Kelly Creek prospect is primarily tundra-mantled metapelitic rocks in saddles and slopes between rubble uplands of schistose marble; bedrock outcrops are only locally present on the marble uplands. The metapelitic rocks have lineated quartz segregations along their foliation; disseminated euhedral pyrite crystals are common.
The Kelly Creek prospect is one of several similar deposits that define a district-level, west-northwest trending belt of gold mineralization about 11 miles long and 2 miles wide. This is the best known and most extensively explored of the deposits in the belt; other are the Wolf (TE107), North Fox (TE109), South Fox (TE108), Wolverine (TE110), Moose (TE111), and Jaeger (TE112) prospects.
The Kelly Creek prospect was discovered by following up gold and arsenic anomalies in soils and stream sediments from the west headwaters of Kelly Creek (Hudson and Wyman, 1983; Hudson, 1984; Cedar Mountain, 2011 [assay]). The soil geochemical surveys defined an irregularly shaped area about 3,000 by 4,00 feet in size with gold values up to 1.4 parts per million (ppm), arsenic up to 1,000 ppm, antimony up to 62 ppm, mercury up to 5 ppm, and silver up to 0.9 ppm. The gold, arsenic, and antimony values define strong, coherent, multi-element anomalies. Mercury is commonly elevated in the soils, but its distribution and concentration are more erratic and it is more widely dispersed at anomalous levels than the other three elements.
Rock samples from frost boils and surface pits 3 to 4 feet deep show that the stronger anomalies are associated with silicified breccia and quartz-stockwork veins in sooty, black carbonaceous quartz schist. The quartz stockwork veins are less than 0.5 inch wide, and locally are broken and recemented by fine-grained, dark siliceous matrix. Two small-diameter diamond drill holes drilled by Anaconda Minerals cut mineralization at shallow depths (Marrs and Ivey, 1984). The holes were oriented N 45 E, were inclined 45 and 60 degrees, and reached depths of 140 and 154 feet. One penetrated 77 feet with 0.032 ounce of gold per ton, and the other 44 feet with 0.035 ounce of gold per ton. The higher gold values seem to be in a zone that dips gently west. All the rocks in these holes had highly anomalous metal contents; gold values are commonly in the several-hundred parts-per-billion range.
In 2011, Cedar Mountain Exploration drilled 18 holes totaling 1820.5 meters (Cedar Mountain Exploration, 2011 [Sept. 26, news release]. Twelve holes were aligned northwest across the saddle centered about 0.5 mile southwest of the center of section 2, T. 4 N., R. 35 W. The best intercepts in the saddle zone were: 1) 16.5 meters that contained 0.85 gram of gold per tonne, this included 7.5 meters with 1.34 grams of gold per tonne; and 2) 26.8 meters with 1.04 grams of gold per tonne, this included 10.1 meters with 2.07 grams of gold per tonne. Another 6 holes were drilled on a strong geochemical anomaly at the head of Kelly Creek about a half mile to the northwest of the saddle. These holes only cut one strong, narrow intercept of 6.10 meters with 1.31 grams of gold per tonne. The drilling indicates that the best grades are associated with zones of quartz veining and stockworks within fractured and sheared carbonaceous schist.
Clay is locally present in fractures and as part of the matrix in breccia. Dolomite and calcite reportedly accompany quartz in the veins in some drill core (Marrs and Ivey, 1984). Pyrite is disseminated in pelitic schist and is present in all mineralized rocks; in part, it is probably of sedimentary origin. Quartz segregations along the foliation in pelitic schist are recrystallized, sugary textured, and vuggy in mineralized rocks. The controls on the mineralization have not been fully identified nor has the distribution of gold; large geochemical anomalies in gold have not been drilled.
Geologic map unit (-165.89892679085, 65.7698618877465)
Mineral deposit model Disseminated and stockwork quartz and gold mineralization in metapelitic rocks. Possibly carbonate-hosted Au-Ag and/or low sulfide Au-quartz vein (Cox and Singer, 1986; models 26a or 36a).
Mineral deposit model number 26a or 36a?
Age of mineralization Unknown but probably mid-to Late Cretaceous as the mineralization postdates regional metamorphism.
Alteration of deposit Brecciation, silicification, and quartz stockwork veining is common in pelitic schist. Some quartz veins contain carbonate minerals. Clay and limonite are present in some mineralized rocks.

Production and reserves

Workings or exploration Exploration includes regional stream sediment geochemistry; a soil geochemical survey on a grid covering a 3,000 by 6,000 foot area; several shallow surface pits; and four small-diameter diamond drill holes. In 2011, Cedar Mountain Exploration drilled 18 holes totaling 1820.5 meters (Cedar Mountain Exploration, 2011 [Sept. 26, news release]. Twelve holes were aligned northwest across the saddle centered about 0.5 mile southwest of the center of section 2, T. 4 N., R. 35 W. Another 6 holes were drilled on a strong geochemical anomaly at the head of Kelly Creek about a half mile northwest of the saddle.
Indication of production None
Reserve estimates None.
Production notes None.

References

References

Cedar Mountain Exploration, 2011, Drilling confirms broad gold zones at Kelly Creek Prospect: http://www.cedarmountainexp.com/news/index.php?&content_id=79 (News Release, September 26, 2011).
Cedar Mountain Exploration Inc., 2011, Kelly Creek project: http://www.cedarmountainexp.com/projects/alaska/kelly_creek_project/ (as of Feb. 10, 2011).
Cedar Mountain Exploration Inc., 2011, New assay date upgrades Cedar Mountain's Kelly Creek Project: http://www.cedarmountainexp.com/_resources/CED_2011_01_25.pdf (News release, January 25, 2011).
Hudson, T.L., 1984, 1983 Seward Peninsula reconnaissance project: Anchorage, Alaska, Anaconda Minerals Company internal report (Report held by Cook Inlet Region, Inc., Anchorage, Alaska).
Hudson, T.L., and Wyman, W. F., 1983, Interim report on areas of Seward Peninsula warranting further prospecting and evaluation: Anchorage, Anaconda Minerals Company internal report, 84 p., 7 plates. (Report held by Cook Inlet Region Inc., Anchorage, Alaska.)
Marrs, C.D., and Ivey, J.A., 1984, 1984 Prospect evaluation project; Kelly Creek (Fox claims): Anchorage, Alaska, Anaconda Minerals Company internal report. (Report held by Cook Inlet Region, Inc., Anchorage, Alaska).
Reporters Travis L. Hudson (Applied Geology); D.J. Grybeck (Contractor, USGS)
Last report date 4/1/2012