Thunder Creek Mine, Yentna Mining District, Matanuska-Susitna Borough, Alaska, USAi
| Regional Level Types | |
|---|---|
| Thunder Creek Mine | Mine |
| Yentna Mining District | Mining District |
| Matanuska-Susitna Borough | Borough |
| Alaska | State |
| USA | Country |
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Latitude & Longitude (WGS84):
62° 29' 49'' North , 151° 0' 10'' West
Latitude & Longitude (decimal):
Type:
Köppen climate type:
Reed and others (1978) indicate that hydrothermally altered zones similar to those in Dollar Creek are observed along Dollar (TL031) and Thunder Creeks (TL032, TL058), at the headwaters of Treasure (TL030), Dutch (TL033) and Bear Creeks (TL017) and at an unnamed locality east of McDoel Peak (TL053).
Location: U. S. Bureau of Mines (1998) locates this mine in the southwest quarter of Section 19, R. 9 W., T. 28 N., of the Seward Meridian. C.C. Hawley and Associates, Inc. (1978, Fig. 4.2-B(3)) show an outline of a claim block on Thunder Creek, a tributary to Cache Creek. This locality is upstream about 0.6 miles from TL032. These two occurrences are two separate areas of placer workings, and appropriately assigned their own ARDF numbers, despite the confusing use of the same name twice.
Geology: Clark and Hawley (1968) describe placer gold associated with an auriferous white quartz conglomerate and breccia deposits at Thunder Creek. The conglomerate is composed of angular quartz fragments mixed with a few rounded quartz and lithic pebbles in fine siliceous clay matrix. Thin layers of lignite are present within the conglomerate which indicates a Tertiary age (Clark and Hawley, 1968). Capps (1931) reports grades of $2 to $2.50 per cubic yard when gold was at $20.67. The gold fineness ranges from 850.5 to 876.5, averaging 865 (Clark and Hawley, 1968.) Concentrates contain gold, ilmente, magnetite, garnet, zircon, pyrite, arsenopyrite, cassiterite, sheelite and native copper (Cobb and Reed, 1980). The white quartz conglomerate placers (e.g. Willow Creek (TL042), Thunder Creek (TL032), and Dollar Creek (TL031)) represent the oldest placers in the Cache Creek area (Clark and Hawley, 1968). Capps (1925) describes the white quartz conglomerate as the basal unit of the Tertiary Kenai Formation. However Clark and Hawley (1968) suggest that the white quartz conglomerate is older and that the Kenai Group was deposited on it. They believe the auriferous conglomerate is near its original source in part because the characteristics of the gold show a common source that has not moved far or has not been reworked. Further, they indicate that the conglomerate is a product of shearing and weathering in situ of argillic altered, auriferous Tertiary quartz porphyry intrusive rocks and associated quartz veins that were emplaced along northeast, high angle normal faults. The lineaments in Dutch and Cache Creeks represent two of these faults. From these paleo-channels gold was reconcentrated into Cache Creek in more recent time. (Mertie, 1919; Clark and Hawley, 1968; C.C.Hawley and Associates, Inc.,1978). Reed and others (1978) indicate that hydrothermally altered zones similar to those in Thunder Creek are observed along Dollar (TL031) and Thunder Creek (TL032), at the headwaters of Treasure (TL030), Dutch (TL033) and Bear Creeks (TL017) and at an unnamed locality east of McDoel Peak (TL053).
Workings: Placer operations are mapped in Thunder Creek from its confluence with Cache Creek to about a mile and a half upstream (C.C.Hawley and Associates, Inc., 1978). Surface placer operations were probably open-cut, sluice and (or) hydraulic operations.
Age: Tertiary and Pleistocene (Clark and Hawley, 1968).
Alteration: Argillic alteration is associated with fault zones (Clark and Hawley, 1968).
Production: Capps (1931) reports grades of $2 to $2.50 per cubic yard when gold was at $20.67. The gold fineness ranges from 850.5 to 876.5, averaging 865 (Clark and Hawley, 1968).
Commodities (Major) - Au, Cu, Sn, W
Development Status: Yes; small.
Deposit Model: Placer Au-PGE (Cox and Singer, 1986; model 39a).
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
10 valid minerals.
Detailed Mineral List:
| ⓘ Arsenopyrite Formula: FeAsS |
| ⓘ Cassiterite Formula: SnO2 |
| ⓘ 'Garnet Group' Formula: X3Z2(SiO4)3 |
| ⓘ Ilmenite Formula: Fe2+TiO3 |
| ⓘ Magnetite Formula: Fe2+Fe3+2O4 |
| ⓘ Native Copper Formula: Cu |
| ⓘ Native Gold Formula: Au |
| ⓘ Pyrite Formula: FeS2 |
| ⓘ Quartz Formula: SiO2 |
| ⓘ Scheelite Formula: Ca(WO4) |
| ⓘ Zircon Formula: Zr(SiO4) |
Gallery:
List of minerals arranged by Strunz 10th Edition classification
| Group 1 - Elements | |||
|---|---|---|---|
| ⓘ | Native Copper | 1.AA.05 | Cu |
| ⓘ | Native Gold | 1.AA.05 | Au |
| Group 2 - Sulphides and Sulfosalts | |||
| ⓘ | Pyrite | 2.EB.05a | FeS2 |
| ⓘ | Arsenopyrite | 2.EB.20 | FeAsS |
| Group 4 - Oxides and Hydroxides | |||
| ⓘ | Magnetite | 4.BB.05 | Fe2+Fe3+2O4 |
| ⓘ | Ilmenite | 4.CB.05 | Fe2+TiO3 |
| ⓘ | Quartz | 4.DA.05 | SiO2 |
| ⓘ | Cassiterite | 4.DB.05 | SnO2 |
| Group 7 - Sulphates, Chromates, Molybdates and Tungstates | |||
| ⓘ | Scheelite | 7.GA.05 | Ca(WO4) |
| Group 9 - Silicates | |||
| ⓘ | Zircon | 9.AD.30 | Zr(SiO4) |
| Unclassified | |||
| ⓘ | 'Garnet Group' | - | X3Z2(SiO4)3 |
List of minerals for each chemical element
| O | Oxygen | |
|---|---|---|
| O | ⓘ Cassiterite | SnO2 |
| O | ⓘ Ilmenite | Fe2+TiO3 |
| O | ⓘ Magnetite | Fe2+Fe23+O4 |
| O | ⓘ Quartz | SiO2 |
| O | ⓘ Scheelite | Ca(WO4) |
| O | ⓘ Zircon | Zr(SiO4) |
| O | ⓘ Garnet Group | X3Z2(SiO4)3 |
| Si | Silicon | |
| Si | ⓘ Quartz | SiO2 |
| Si | ⓘ Zircon | Zr(SiO4) |
| Si | ⓘ Garnet Group | X3Z2(SiO4)3 |
| S | Sulfur | |
| S | ⓘ Arsenopyrite | FeAsS |
| S | ⓘ Pyrite | FeS2 |
| Ca | Calcium | |
| Ca | ⓘ Scheelite | Ca(WO4) |
| Ti | Titanium | |
| Ti | ⓘ Ilmenite | Fe2+TiO3 |
| Fe | Iron | |
| Fe | ⓘ Arsenopyrite | FeAsS |
| Fe | ⓘ Ilmenite | Fe2+TiO3 |
| Fe | ⓘ Magnetite | Fe2+Fe23+O4 |
| Fe | ⓘ Pyrite | FeS2 |
| Cu | Copper | |
| Cu | ⓘ Native Copper | Cu |
| As | Arsenic | |
| As | ⓘ Arsenopyrite | FeAsS |
| Zr | Zirconium | |
| Zr | ⓘ Zircon | Zr(SiO4) |
| Sn | Tin | |
| Sn | ⓘ Cassiterite | SnO2 |
| W | Tungsten | |
| W | ⓘ Scheelite | Ca(WO4) |
| Au | Gold | |
| Au | ⓘ Native Gold | Au |
Other Databases
| Link to USGS - Alaska: | TL058 |
|---|
Other Regions, Features and Areas containing this locality
North AmericaContinent
North America PlateTectonic Plate
- Farewell buried DomainDomain
- Farewell TerranePassive Margin
- Susitna BasinBasin
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