| Main commodities | Au |
|---|---|
| Other commodities | Ag |
| Ore minerals | arsenopyrite; gold; pyrite |
| Gangue minerals | carbonate minerals; chlorite; quartz; sericite |
| Quadrangle map, 1:250,000-scale | VA |
|---|---|
| Quadrangle map, 1:63,360-scale | A-8 |
| Latitude | 61.2078 |
| Longitude | -146.7926 |
| Nearby scientific data | Find additional scientific data near this location |
| Location and accuracy | This mine is 3.6 miles west of Mount Cameron on the southwest side of a nunatak in the eastern part of Columbia Glacier (Pickthorn, 1982, sheet 1); it is at an elevation of about 2,300 feet in the NW1/4 section 2, T. 8 S., R. 9 W., of the Copper River Meridian. This mine is located to within one-quarter mile. It is locality 1 of Cobb and Matson (1972) and locality 1 of Winkler and others (1981 [OFR 80-892-B]). |
Geologic descriptionGold-bearing quartz veins cut metaflysch of the Valdez Group and a Tertiary granitic plug at this locality (Smith, 1937, 1939). The quartz fills gashes in the granitic rock and surrounding hornfelsed metagraywacke. The veins contain sulfide minerals common to other gold-bearing quartz veins in the area; arsenopyrite and pyrite (Smith, 1937). Open cuts and at least 372 feet of underground workings explored the deposit (Jansons and others, 1984). Several tons of ore were recovered from open cuts and processed. The total production is 76 ounces of gold and 20 ounces of silver (Jansons and others, 1984). The U.S. Bureau of Mines collected seven chip samples from this area that contained 0.18 ppm to 2.52 ounces of gold per ton and 0.3 ppm to 0.89 ounce of silver per ton; a grab sample contained 14 ppm gold and 3.3 ppm silver. Eight other samples from this area contained up to 9.0 ppm gold (Pickthorn, 1982). These veins are probably similar to other gold-bearing quartz veins cutting metaflysch of the Valdez Group in the southern Valdez quadrangle. Data summarized by Goldfarb and others (1997) show that gold-bearing quartz veins in the Valdez Group commonly contain pyrite, arsenopyrite, carbonate minerals, chlorite, and white mica and formed from water-rich fluids with 5 to 15 mole percent CO2 and significant amounts of CH4, N2, and H2S. The vein-forming fluid salinities were less than 8 percent, vein formation temperatures ranged from 225 to 375 degrees centigrade, and emplacement depths varied from 3 to 10 kilometers. The vein-forming fluids were produced by metamorphic devolatilization reactions. Radiometric dating indicates that the veins formed from 57 to 49 Ma (Goldfarb and others, 1997, p. 171), when deep parts of the accreted Valdez Group flysch underwent high-grade metamorphism and partial melting (Hudson, 1994). | |
| Geologic map unit | (-146.79467757699, 61.2072737230285) |
|---|---|
| Mineral deposit model | Low-sulfide Au-quartz veins (Cox and Singer, 1986; model 36a) |
| Mineral deposit model number | 36a |
| Age of mineralization | Radiometric dating indicates that the gold-bearing quartz veins in the Valdez Group formed from 57 to 49 Ma (Goldfarb and others, 1997, p. 171), when deep parts of the accreted Valdez Group flysch underwent high-grade metamorphism and partial melting (Hudson, 1994). |
| Alteration of deposit | Country rocks to gold-bearing quartz veins in Valdez Group metaflysch can be variably silicified, carbonitized, and sericitized (Goldfarb and others, 1997). |
| Workings or exploration | Open cuts and at least 372 feet of underground workings explored the deposit (Jansons and others, 1984). |
|---|---|
| Indication of production | Yes; small |
| Production notes | Several tons of ore were recovered from open cuts and processed. The total reported production is 76 ounces of gold and 20 ounces of silver (Jansons and others, 1984). |
| MRDS Number | A011442 |
|---|---|
ReferencesGoldfarb, R.J., Miller, L.D., Leach, D.L., and Snee, L.W, 1997, Gold deposits in metamorphic rocks in Alaska, in Goldfarb, R.J., and Miller, L.D., eds., Mineral Deposits of Alaska: Economic Geology Monograph 9, p. 151-190.
Hudson, T.L., 1994, Crustal melting events in Alaska, in Plafker, G., and Berg, H. C., eds., The Geology of Alaska: Geological Society of America, DNAG, The Geology of North America, Vol. G-1, p. 657-670.
Pickthorn, W.J., 1982, Stable isotope and fluid inclusion study of the Port Valdez district, southern Alaska: Los Angeles, University of California at Los Angeles, M.S. thesis, 66 p.
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| Reporters | Travis L. Hudson |
| Last report date | 12/14/2001 |