|Quadrangle map, 1:250,000-scale||SO|
|Quadrangle map, 1:63,360-scale||C-4|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||This prospect is on the low ridge between Eldorado Creek (ARDF SO007) and Lost Creek, 1.7 miles north-northwest of Bluff. It is at an elevation of about 320 feet and is locality 20 of Cobb (1972, MF 445; 1978, OF 78-181).|
Geologic descriptionA 5.5-foot-wide quartz vein or silicified zone at a marble-schist contact carries sparse chalcopyrite, pyrite, malachite, and azurite; the central 18 inches is barren (Cathcart, 1922). Assays reported by early workers ran up to up to $80 per ton of gold (3.9 ounces per ton) (Cathcart, 1922). Bedrock in this area is part of a lower Paleozoic metasedimentary marble-schist assemblage (Herreid, 1965; Till and others, 1986). The mineralization may be mid-Cretaceous in age, the age of some lode gold deposits on southern Seward Peninsula. The southern Seward Peninsula lode gold deposits formed as a result of mid-Cretaceous metamorphism (Apodoca, 1994; Ford, 1993, Ford and Snee, 1996; Goldfarb and others, 1997) that accompanied regional extension (Miller and Hudson, 1991) and crustal melting (Hudson, 1994). This higher temperature metamorphism was superimposed on high pressure/low temperature metamorphic rocks of the region.
|Geologic map unit||(-163.766586001936, 64.5942635308616)|
|Mineral deposit model||Quartz vein or replacement at marble-schist contact; possibly low sulfide Au quartz vein (Cox and Singer, 1986; model 36a).|
|Mineral deposit model number||36a|
|Age of mineralization||Not known - possibly mid-Cretaceous.|
|Alteration of deposit||Silicification is indicated.|
|Workings or exploration||Exploration consists of two, old shallow trenches, 2 feet deep and 20 feet long (Cathcart, 1922).|
|Indication of production||None|
Apodoca, L.E., 1994, Genesis of lode gold deposits of the Rock Creek area, Nome mining district, Seward Peninsula, Alaska: Boulder, Colorado, University of Colorado, Ph.D. dissertation, 208 p.
Cathcart, S.H., 1922, Metalliferous lodes in southern Seward Peninsula: U.S. Geological Survey Bulletin 722-F, p. 163-261.
Cobb, E.H., 1972, Metallic mineral resources map of the Solomon quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-445, 1 sheet, scale 1:250,000.
Cobb, E.H., 1978, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Solomon quadrangle, Alaska: U.S. Geological Survey Open-File Report 78-181, 185 p.
Ford, R.C., 1993, Geology, geochemistry, and age of gold lodes at Bluff and Mt. Distin, Seward Peninsula, Alaska: Golden, Colorado School of Mines, Ph.D. dissertation, 302 p.
Ford, R.C., and Snee, L.W., 1996, 40Ar/39Ar thermochronology of white mica from the Nome district, Alaska--The first ages of lode sources to placer gold deposits in the Seward Peninsula: Economic Geology, v. 91, p. 213-220.
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.
Herreid, G.H., 1965, Geology of the Bluff area, Solomon quadrangle, Seward Peninsula, Alaska: Alaska Division of Geological and Geophysical Surveys Geological Report 10, 21 p., 1 sheet, scale 1:40,000.
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.
Miller, E.L., and Hudson, T.L., 1991, Mid-Cretaceous extensional fragmentation of a Jurassic-Early Cretaceous compressional orogen, Alaska: Tectonics, v. 10, p. 781-796.
|Reporters||Travis L. Hudson (Applied Geology)|
|Last report date||8/19/1999|