| GMRAP ID | 3386 |
|---|---|
| Alternate names | Tim's Greisen, Tim's Gossan, TG, TG North |
| Tract name | Yukon-Tanana Upland (003pCu5003) |
| Site status | prospect |
| Country | United States |
|---|---|
| State or province | Alaska |
| Geographic location | -157.5568, 64.1736 |
| Geologic map unit | -157.5568, 64.1736 |
| Nearby data |
| Deposit type | Porphyry copper |
|---|---|
| Age (Ma) | 74Ma |
| Age determination method | K-Ar potassium feldspar |
| Age range | 74 ±2.8 Ma (K-Ar potassium feldspar); 72.9 ±2.8 Ma (unknown method) |
| Age reference | Harris (1985); Western Alaska Copper and Gold Co. (2012) |
| Minerals | argentojarosite, beudantite, chalcocite, chalcopyrite, covellite, jarosite, molybdenite, native copper, pyrite, pyrrhotite, sphalerite |
| Tectonic setting | continental margin |
| Stratigraphic age | Late Cretaceous |
| Development status | Prospect |
|---|---|
| Major commodities | Ag, Cu, Mo |
| Minor commodities | Pb, W, Zn |
| Gold-Moly ratio | -9999 |
| Comments | Discovered in early 1980s. Greenschist and amphibolite country rocks are intruded by a large intrusive complex (two lobes with six types of porphyritic intrusive rock and an intrusive microbreccia). Mineralization occurs as (1) veins containing molybdenite, chalcopyrite, pyrite, and pyrrhotite; (2) gossan containing argentojarosite, jarosite, and beudantite; (3) a supergene zone beneath the gossan containing chalcocite, covellite, native copper, and chalcopyrite; and (4) calc-silicate wall rocksnear the intrusive that contain pyrite, chalcopyrite, and sphalerite. Alteration consists of early potassic and propylitic alteration in the microbreccia and earlier porphyritic intrusions, and later sericite-quartz-pyrite alteration throughout theintrusive complex. The deposit also has undergone supergene enrichment. Drilled 7 holes totaling 1,668 m in 1981; drilled two shallow ""Winkie"" holes in 1982; trenches, geologic mapping and geophysical surveys, extensive sediment and soil sampling program. |
|---|---|
| Study area name | United States |
| References | U.S. Geological Survey (2014a); Harris (1985); Western Alaska Copper and Gold Co. (2012) |
| Site reference | U.S. Geological Survey National Mineral Resource Assessment Team (2002) |