Unnamed Occurrence (ARDF - MG074; east of headwaters of Windy Fork), McGrath Mining District, Bethel Census Area, Alaska, USAi
| Regional Level Types | |
|---|---|
| Unnamed Occurrence (ARDF - MG074; east of headwaters of Windy Fork) | - not defined - |
| McGrath Mining District | Mining District |
| Bethel Census Area | Census Area |
| Alaska | State |
| USA | Country |
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Latitude & Longitude (WGS84):
62° 0' 46'' North , 153° 55' 33'' West
Latitude & Longitude (decimal):
Köppen climate type:
See other examples of shale-hosted mineralization in McGrath quadrangle (MG029, MG049, MG051, MG064, MG071).
Location: This unnamed occurrence is located on a moderately steep, southeast facing spur overlooking the headwaters of the west fork of Post River. It is about 3 kilometers east of the headwaters of the Windy Fork of the Kuskokwim River, at an elevation of 5,050 feet (1,540 m), in the NE1/4 sec. 7, T. 22 N., R. 25 W., of the Seward Meridian. The reporter sampled the site in 1982.
Geology: The unnamed occurrence consists of shale-hosted Zn-Ag (Pb-Cu) mineralization in the Lower Ordovician to Lower Silurian Post River Formation, a unit of the Dillinger subterrane (Bundtzen, Harris, and Gilbert, 1997). The mineralized zone is parallel to bedding and is a distinctly sulfur-stained, carbonaceous shale bed about one meter thick. Only disseminated pyrite was identified in the zone. Although isotopic data is lacking, Bundtzen, Harris, and Gilbert (1997) regarded the occurrence as possible sedimentary exhalitive (?) lead-zinc mineralization. Two random grab samples from the mineralized shale contained up to 0.86 percent zinc, 4.5 grams/tonne silver, 104 ppm copper, and 186 ppm lead (Bundtzen and others, 1988).
Workings: The reporter and Kristi McDonald sampled the mineralized zone in 1982. Two random grab samples from the mineralized shale yielded up to 0.86 percent zinc, 4.5 grams/tonne silver, 104 ppm copper, and 186 ppm lead (Bundtzen and others, 1988).
Age: Inferred to be Lower Ordovician to Lower Silurian (Bundtzen, Harris, and Gilbert, 1997), assuming it is a syngenetic deposit.
Alteration: None.
Reserves: None.
Commodities (Major) - Ag, Zn; (Minor) - Cu, Pb
Development Status: No
Deposit Model: Sedimentary exhalitive lead-zinc (Cox and Singer, 1986; model 31b).
Select Mineral List Type
Standard Detailed Gallery Strunz Chemical ElementsCommodity List
This is a list of exploitable or exploited mineral commodities recorded at this locality.Mineral List
1 valid mineral.
Gallery:
List of minerals arranged by Strunz 10th Edition classification
| Group 2 - Sulphides and Sulfosalts | |||
|---|---|---|---|
| ⓘ | Pyrite | 2.EB.05a | FeS2 |
Other Databases
| Link to USGS - Alaska: | MG074 |
|---|
Other Regions, Features and Areas containing this locality
North AmericaContinent
North America PlateTectonic Plate
- Farewell-McGrath DomainDomain
- Farewell TerranePassive Margin
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