| Main commodities | Cu; Pb; Sn |
|---|---|
| Other commodities | Ag; Au; Be; Bi; F; Mo; Sb; W; Zn |
| Ore minerals | arsenopyrite; chalcopyrite; fluorite; galena; magnetite; molybdenite; sphalerite; stibnite |
| Gangue minerals | calc-silicate minerals; quartz |
| Quadrangle map, 1:250,000-scale | SP |
|---|---|
| Quadrangle map, 1:63,360-scale | C-5 |
| Latitude | 67.51 |
| Longitude | -155.08 |
| Nearby scientific data | Find additional scientific data near this location |
| Location and accuracy | This site is a composite of four occurrences (localities 18-22 of Grybeck and Nelson, 1981) in an area of about 6 square miles on both sides of Tupik Creek. The coordinates are for the center of the area in the NW1/4 of sec. 3, T. 24 N., R. 17 E., of the Kateel River Meridian. Location of area accurate to within 2000 ft. |
Geologic descriptionThis composite site represents a number of occurrences that share a common geologic environment marked by flat-lying Paleozoic gneiss and schist and Devonian and Silurian limestone and shale that overlie a large Devonian gneissic granite pluton. Small erratic skarn bodies are common where carbonates are present. Five mineral occurrences within the area are specifically noted by Grybeck and Nelson (1981), and others probably could be found with some search. Most are small and erratic; they rarely are more than a few feet or tens of feet in area and they are usually hundreds of feet or more apart. Impressive hand samples containing ore minerals were collected within the area, but no widespread concentration of ore minerals was noted. The mineralogy of the occurrences is highly variable. It includes various combinations of galena, sphalerite, stibnite, chalcopyrite, magnetite, and molybdenite, often associated with quartz and fluorite, and, in the skarns, various calc-silicate minerals. Highly select grab samples of the more sulfide-rich rocks contain up to 55 ppm Ag, 55 ppm Au, 70 ppm Be, 700 ppm Bi, 1000 ppm Sn, and, in the skarns, 300 ppm W. The overall environment is that of contact metamorphism marked by very spotty metasomatic mineralization. The source of the metals is the large Devonian granite pluton that underlies most of the area. Similar mineralization is recognized elsewhere in the Brooks Range and is described by Newberry and others (1986). | |
| Geologic map unit | (-155.082778339064, 67.5094958250183) |
|---|---|
| Mineral deposit model | Skarn (Cox and Singer, 1986; model 14b) |
| Mineral deposit model number | 14b |
| Age of mineralization | Deposits formed by metasomatic introduction of metals related to intrusion of Devonian granite. |
| Alteration of deposit | Metasomatic alteration related to contact metamorphism: calc-silicate minerals, sulfides and quartz. |
| Workings or exploration | Samples were mostly collected during spot stops and short traverses during geologic mapping by the USGS in the late 1970s. |
|---|---|
| Indication of production | None |
Additional commentsLocated within Gates of the Arctic National Park. | |
| MRDS Number | A011927 |
|---|---|
ReferencesNewberry, R.J., Dillon, J.T., and Adams, D.D., 1986, Regionally metamorphosed calc-silicate-hosted deposits of the Brooks Range, northern Alaska: Economic Geology, v. 81, p. 1728-1752.
| |
| Reporters | S.W. Nelson (Anchorage, Alaska) |
| Last report date | 9/20/1999 |