| Main commodities | Au |
|---|---|
| Other commodities | Cu |
| Ore minerals | chalcopyrite; gold; pyrite; tetrahedrite |
| Gangue minerals | orthoclase; quartz; tourmaline |
| Quadrangle map, 1:250,000-scale | AN |
|---|---|
| Quadrangle map, 1:63,360-scale | D-7 |
| Latitude | 61.9 |
| Longitude | -149.28 |
| Nearby scientific data | Find additional scientific data near this location |
| Location and accuracy | Prospect located near the head of the north fork of Peters Creek, a northern tributary of Willow Creek. Chapin (1921) reported the creek name as Peterson Creek but the name has since changed. Accurate within 1 mile. Sec. 21, T. 21 N., R. 1 E., of the Seward Meridian. |
Geologic descriptionChapin (1921) reported that three parallel granitic dikes cut tonalite country rock. The dikes are composed of quartz, orthoclase, and clusters of tourmaline. They strike N 63 E and one of these dikes, 8 ft wide, gradually passes along its strike into a quartz vein. The vein carries some gold and visible particles of chalcopyrite and tetrahedrite. Several short, intersecting gash veins of quartz intersect this main vein with considerable pyrite. These veins pinch out a short distance from the main fissure, but the persistence of the fissure vein is unknown. It appears to merge into a granite dike in one direction and is untracable due to debris (talus or glacial deposits ?) in the other direction. The bedrock is the Late Cretaceous Willow Creek Pluton, a zoned pluton: the outer part consists of hornblende quartz diorite and lesser hornblende tonalite; the core consists of hornblende-biotite granodiorite, and lesser hornblende-biotite quartz monzodiorite and biotite quartz monzonite. Wall-rock alteration within a few inches of the veins is intense, but seldom extends more than 10 to 12 inches beyond the quartz filling. Sericitization and carbonate alteration predominate, but there is some pyritization and in the outer parts of the alteration zone chloritization is present (Ray, 1954). | |
| Geologic map unit | (-149.282210140623, 61.8994772980626) |
|---|---|
| Mineral deposit model | Low-sulfide Au-quartz veins (Cox and Singer, 1986; model 36a) |
| Mineral deposit model number | 36a |
| Age of mineralization | Late Cretaceous or younger; the dikes and veins cut the Late Cretaceous Willow Creek Pluton. |
| Alteration of deposit | Wall-rock alteration within a few inches of the veins is intense, but seldom extends more than 10 to 12 inches beyond the quartz filling. Sericitization and carbonate alteration predominate, but there is some pyritization and in the outer parts of the alteration zone chloritization is present (Ray, 1954). |
| Workings or exploration | Explored by open cuts made on both the main vein and the gash veins, and a tunnel was started on the main vein (Chapin, 1921). |
|---|---|
| Indication of production | Undetermined |
| MRDS Number | A106238 |
|---|---|
| Reporters | D.P. Bickerstaff (USGS contractor); S.W. Huss (USGS) |
| Last report date | 7/30/1998 |