|Quadrangle map, 1:250,000-scale||SO|
|Quadrangle map, 1:63,360-scale||D-4|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||Ophir Creek is a major north tributary to the Niukluk River; its mouth is 3 miles upstream from Council. The entire Ophir Creek drainage within the Solomon D-4 quadrangle, over 6 miles of stream and many adjacent bench deposits, has been placer mined. Placer mining continued upstream into the Bendeleben A-4 quadrangle (BN099). This is locality 120 of Cobb (1972, MF 445; 1978, OF 78-181).|
Geologic descriptionOphir Creek is the most important producer of placer gold in the Council district. The majority of the 707,000 ounces of gold production recorded for the Council district probably came from Ophir Creek (Hudson and DeYoung, 1978). Placer gold was discovered here in 1897 and extensive mining, especially dredging, has taken place over its entire length downstream from the mouth of Crooked Creek in the Bendeleben A-4 quadrangle. Benches have been mined at many places along the drainage. In the Solomon D-4 quadrangle, Ophir Creek is less than 250 feet above sea level. This low elevation suggest the possiblity that the character of Ophir Creek placer deposits was influenced by Quaternary sea level fluctuations. The presence of terrace gravels and bench placer deposits indicates that two or more cycles of placer deposit development have occurred. However, there are gold-bearing lode deposits in lower Paleozoic metasedimentary bedrock (schist and marble; Till and others, 1986) near the mouth of Ophir Creek (Smith and Eakin, 1911), the mouth of Crooked Creek (BN100), and the headwaters of Crooked Creek (BN104). The gold-bearing rocks are most commonly described as areas with small quartz or quartz-carbonate veins in schist or schistose limestone.
|Geologic map unit||(-163.660619478511, 64.9572739093234)|
|Mineral deposit model||Placer Au-PGE (Cox and Singer, 1986; model 39a).|
|Mineral deposit model number||39a|
|Age of mineralization||Quaternary; the elevation, less than 250 feet above sea level, location proximal to Niukluk River lowlands, and the many bench deposits suggest that these placers are the result of more than one cycle of erosion and deposition and that sea level fluctuations influenced their development.|
|Workings or exploration||Gold was discovered in 1897 and the entire creek and many areas of bench deposits have been placer mined, much by dredging. A dredge continued to be active in the area at least as recently as 1968 and probably later.|
|Indication of production||Yes; medium|
|Production notes||Ophir Creek is the most important producer of placer gold in the Council district. The majority of the 707,000 ounces of gold production recorded for the Council district probably came from Ophir Creek (Hudson and DeYoung, 1978).|
|MRDS Number||A010717; A012630; D002169|
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.
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.
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||8/19/1999|