Sheep Creek-1 Occurrence, Yukon-Koyukuk Census Area, Alaska, USAi
| Regional Level Types | |
|---|---|
| Sheep Creek-1 Occurrence | Occurrence |
| Yukon-Koyukuk Census Area | Census Area |
| Alaska | State |
| USA | Country |
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Latitude & Longitude (WGS84):
62° 20' 31'' North , 153° 47' 56'' West
Latitude & Longitude (decimal):
Type:
Köppen climate type:
Location: The Sheep Creek-1 occurrence is located in the main tributary valley of Sheep Creek about 2.0 kilometers upstream from the confluence of the main tributary and the Smith Lake fork at an elevation of 2,800 feet (853 m) in the SW1/4 sec. 18, T. 26 N., R. 24 W., of the Seward Meridian. Sheep Creek-1 is mineral locality #12 of Bundtzen, Harris, and Gilbert (1997). The reporter found the site in 1981.
Geology: The Sheep Creek-1 occurrence is a discontinuous zone of metal-bearing, sulfur-rich shale and siltstone of the Lower Ordovician to Lower Silurian Post River Formation, a unit of the Dillinger subterrane (Bundtzen, Harris, and Gilbert, 1997). The observed shale-hosted mineralization contains graptolites that correspond to the Monograptus spiralus zone or of Lower Silurian age. The mineralized zones occur in distinctive areas where a bright yellow sulfur staining is seeping out of pyrite-rich lamina in the black shale lenses and horizons. Within the sulfur-rich zones, disseminated pyrite, and sphalerite are found in 2 to 4 centimeter thick bands. Bundtzen, Harris, and Gilbert (1997) regard the Sheep Creek-1 occurrence as a sedimentary exhalitive lead-zinc deposit type; however, it may also be an epigenetic occurrence related to nearby plutonic sources. Random chip samples reported by Bundtzen, Kline, and Clough (1982) and Bundtzen, Harris, and Gilbert (1997) from four stratiform horizons contained an average 600 ppm lead, 1,700 ppm zinc, 1,000 ppm vanadium, and 2.7 grams/tonne silver. Smith and Albanese (1985) reported a single sample (#2526) from the Sheep Creek-1 occurrence contained 720 ppm lead, 37.1 grams/tonne silver, and 472 ppm antimony.
Workings: The reporter first recognized the shale-hosted mineralization in 1981 (Bundtzen, Kline, and Clough, 1982). Random chip samples reported by Bundtzen, Kline, and Clough (1982) and Bundtzen, Harris, and Gilbert (1997) from four horizons of shale-hosted mineralization contained an average 600 ppm lead, 1,700 ppm zinc, 1,000 ppm vanadium, and 2.7 grams/tonne silver. Smith and Albanese (1985) reported that a single sample (#2526) from the Sheep Creek-1 occurrence contained 720 ppm lead, 37.1 grams/tonne silver, and 472 ppm antimony.
Age: Inferred to be Lower Silurian, based on graptolite identification.
Alteration: Strong sulfurous alteration.
Reserves: None.
Commodities (Major) - Ag, Pb, Zn; (Minor) - V
Development Status: No
Deposit Model: Sedimentary exhalitive Pb-Zn(?) (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 |
| ⓘ | Pyrite | 2.EB.05a | FeS2 |
| Group 4 - Oxides and Hydroxides | |||
| ⓘ | Quartz | 4.DA.05 | SiO2 |
List of minerals for each chemical element
| O | Oxygen | |
|---|---|---|
| O | ⓘ Quartz | SiO2 |
| Si | Silicon | |
| Si | ⓘ Quartz | SiO2 |
| S | Sulfur | |
| S | ⓘ Pyrite | FeS2 |
| S | ⓘ Sphalerite | ZnS |
| Fe | Iron | |
| Fe | ⓘ Pyrite | FeS2 |
| Zn | Zinc | |
| Zn | ⓘ Sphalerite | ZnS |
Other Databases
| Link to USGS - Alaska: | MG051 |
|---|
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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