Unnamed Occurrence (ARDF - MG071; on a tributary to Windy Fork), Yukon-Koyukuk Census Area, Alaska, USAi
| Regional Level Types | |
|---|---|
| Unnamed Occurrence (ARDF - MG071; on a tributary to Windy Fork) | - not defined - |
| Yukon-Koyukuk Census Area | Census Area |
| Alaska | State |
| USA | Country |
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Latitude & Longitude (WGS84):
62° 7' 48'' North , 153° 55' 33'' West
Latitude & Longitude (decimal):
Köppen climate type:
Location: Occurrence is located in a bedrock outcrop on the north side of an unnamed west-flowing tributary stream to Windy Fork; it is at an elevation of 3,900 feet (1,189 m) in the NE1/4 sec. 31, T. 24 N., R. 25 W., of the Seward Meridian. The reporter investigated the site in 1983 and in 1997. Note that the occurrence is properly located in Bundtzen and others (1988; #8), but mislocated in Bundtzen, Harris, and Gilbert, (1997; #23).
Geology: This unnamed occurrence consists of three thin, stratiform sulfide layers in black shale of the Lower Ordovician to Lower Silurian Post, River Formation a unit of the Dillinger subterrane (Bundtzen, Harris, and Gilbert, 1997). The sulfide beds are isoclinally folded along with host strata and are believed to be syngenetic in origin. The occurrence is just below the contact between the Post River Formation and the mid-Silurian Terra Cotta Mountains Sandstone, and hence has an inferred age of Early Silurian. Three 6 centimeter thick sulfide layers mainly contain pyrite, with minor to trace disseminated sphalerite and galena (Bundtzen and others, 1988; Bundtzen Harris, and Gilbert, 1997). Grab samples of one sulfide bearing horizon contained 700 ppm zinc, 1.2 grams/tonne silver, and 31 ppm molybdenum.
Workings: The reporter first found the occurrence in 1983 (Bundtzen and others, 1988). Grab samples of one sulfide bearing horizon contained 700 ppm zinc, 1.2 grams/tonne silver, and 31 ppm molybdenum.
Age: Undated, inferred to be Early Silurian, based on stratigraphic evidence.
Reserves: None.
Commodities (Major) - Ag, Zn; (Minor) - Mo
Development Status: No
Deposit Model: Sedimentary exhalitive lead-zinc (?) (Cox and Singer, 1986; model 31a).
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
3 valid minerals.
Gallery:
List of minerals arranged by Strunz 10th Edition classification
| Group 2 - Sulphides and Sulfosalts | |||
|---|---|---|---|
| ⓘ | Sphalerite | 2.CB.05a | ZnS |
| ⓘ | Galena | 2.CD.10 | PbS |
| ⓘ | Pyrite | 2.EB.05a | FeS2 |
List of minerals for each chemical element
| S | Sulfur | |
|---|---|---|
| S | ⓘ Galena | PbS |
| S | ⓘ Pyrite | FeS2 |
| S | ⓘ Sphalerite | ZnS |
| Fe | Iron | |
| Fe | ⓘ Pyrite | FeS2 |
| Zn | Zinc | |
| Zn | ⓘ Sphalerite | ZnS |
| Pb | Lead | |
| Pb | ⓘ Galena | PbS |
Other Databases
| Link to USGS - Alaska: | MG071 |
|---|
Other Regions, Features and Areas containing this locality
North AmericaContinent
North America PlateTectonic Plate
- Farewell-McGrath DomainDomain
- Farewell TerranePassive Margin
USA
- Alaska
- Yukon-Koyukuk Census Area
- McGrath Mining DistrictMining District
- Yukon-Koyukuk Census Area
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