|Quadrangle map, 1:250,000-scale||VA|
|Quadrangle map, 1:63,360-scale||A-7|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||This mine is near the mouth of McAllister Creek on Shoup Bay (Pickthorn, 1982, sheet 2); it is at an elevation of about 100 feet in the NE1/4 section 35, T. 8 S., R. 8 W., of the Copper River Meridian. This mine is located to within one-quarter mile. It is locality 13 of Cobb and Matson (1972) and locality 10 of Winkler and others (1981 [OFR 80-892-B]).|
A shear zone, commonly about 0.5 to 2 feet thick but locally as much as 6 feet thick, cuts metaflysch of the Valdez Group; the zone contains quartz-chlorite-calcite veinlets with gold, pyrite, chalcopyrite, arsenopyrite, sphalerite, and galena (Johnson, 1915). Brecciated country rocks in the shear zone are silicified and cemented with pyritiferous quartz (Brooks, 1912). The mineralized zone, which strikes about N60W and dips 70S, is traceable on the surface for as much as 1,100 feet. By 1916, a 250-foot adit with a raise and a 170-foot shaft with two 50-foot drifts at the bottom explored the deposit. A few small ore shipments, including 30 tons in 1912, were made from this mine. U.S. Bureau of Mines sampling included four chip samples that contained from 0.2 ppm to 0.109 ounce of gold per ton and from 0.2 ppm to 0.18 ounce of silver per ton, and two grab samples that contained 0.005 and 0.257 ounce of gold per ton and less than 0.2 and 0.2 ounce of silver per ton. Eleven other samples from this area contained 0.4 to 16 ppm gold (Pickthorn, 1982).This deposit is 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||(-146.6105354563, 61.1353762521863)|
|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||The mineralized zone was reported to be traceable on the surface for as much as 1,100 feet. By 1916, a 250-foot adit with raise and a 170-foot shaft with two 50-foot drifts at the bottom explored the deposit.|
|Indication of production||Yes; small|
|Production notes||A few small ore shipments, including 30 tons in 1912, were made from this mine.|
Cobb, E.H., and Matson, N.A., Jr., 1972, Metallic mineral resources map of the Valdez quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-438, 1 sheet, scale 1:250,000.
Goldfarb, 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.
Johnson, B.L., 1915, Mining on Prince William Sound: U.S. Geological Survey Bulletin 622-E, p. 131-139.
Winkler, G.R., Miller, R.J., MacKevett, E.M., Jr., and Holloway, C.D., 1981, Map and summary table describing mineral deposits in the Valdez quadrangle, southern Alaska: U.S. Geological Survey Open-File Report 80-892-B, 2 sheets, scale l:250,000.
|Reporters||Travis L. Hudson|
|Last report date||12/14/2001|