|Quadrangle map, 1:250,000-scale||BN|
|Quadrangle map, 1:63,360-scale||A-4|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||Crooked Creek is a short, 2.3 mile long west tributary to Ophir Creek. The mouth of Crooked Creek is 7,500 feet upstream (on Ophir Creek) from the southern boundary of the Bendeleben quadrangle. This occurrence is described as being near the mouth of Crooked Creek and is only approximately located, probably within one mile. It is locality 13 of Cobb (1972; MF 417; 1975; OFR 75-429).|
Geologic descriptionA 12 foot-wide mineralized zone in schistose limestone (marble) contains quartz veins and pyrite. Collier and others (1908) report that a quartz stringer with pyrite assayed 0.06 ounces/ton Au and a trace of silver from this area and Smith and Eakin (1911) were told that assays as high as 0.04 ounces/ton Au had been obtained from this occurrence. Bedrock in the area is metasedimentary schist and marble of a Lower Paleozoic assemblage (Till and others, 1986).
|Geologic map unit||(-163.672624738879, 65.0192748819622)|
|Mineral deposit model||Gold-bearing quartz veins in schistose marble|
|Age of mineralization||Possibly mid-Cretaceous; if gold-bearing lode structures are present here they may be similar in age to some lode gold deposits of 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.|
|Alteration of deposit||Quartz veining and possibly pyrite dissemination in the metasedimentary host rocks is present.|
|Workings or exploration||This occurrence may have been exposed by surface placer mine workings on a bench along lower Crooked Creek.|
|Indication of production||None|
|Production notes||Placer gold from lower Crooked Creek was both coarse and rounded as well as sharp, angular, and with quartz attached (Smith and Eakin, 1911). Collier and others (1908) also noted that the fragile and crystalline placer gold suggested a local source.|
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.
Cobb, E.H., 1972, Metallic mineral resources map of the Bendeleben quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-417, 1 sheet, scale 1:250,000.
Cobb, E.H., 1975, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Bendeleben quadrangle, Alaska: U.S. Geological Survey Open-File Report 75-429, 123 p.
Collier, A.J., Hess, F.L., Smith, P.S., and Brooks, A.H., 1908, The gold placers of parts of Seward Peninsula, Alaska, including the Nome, Council, Kougarok, Port Clarence, and Goodhope precincts: U.S. Geological Survey Bulletin 328, 343 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.
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.
Smith, P.S., and Eakin, H.M., 1911, A geologic reconnaissance in southeastern Seward Peninsula, and the Norton Bay-Nulato region, Alaska: U.S. Geological Survey Bulletin 449, 146 p.
|Reporters||Travis L. Hudson (Applied Geology)|
|Last report date||3/15/1999|