|Quadrangle map, 1:250,000-scale||GU|
|Quadrangle map, 1:63,360-scale||D-1|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||This placer (Cobb, 1979 [OF 79-1247 p. 6] is near the head of Boulder Creek (which is not named on the Gulkana D-1 quadrangle) at an elevation of about 3,800 feet. The prospect is about 1000 feet south of the center of section 36, T. 12 N., R. 7 E., Copper River Meridian. The prospect is shown as a placer on figure 5 of Richter (1966). It is shown as location 22 of Richter and Matson (1972) and locality 21 of MacKevett and Holloway (1977).|
Geologic descriptionBoulder Creek is mainly underlain by altered volcanic rocks of the Pennsylvanian to Permian, Tetelna Formation. The mine approximately coincides with a dike-like intrusion of Jurassic diorite which cuts the Tetelna Formation. The dike-like intrusion strike north-northwest for at least a mile (Richter 1966; Richter and Matson, 1968, figures 4-8; WGM, written communication. 1980). Stream sediment samples collected on the dike and below it in Boulder Creek were anomalous in gold. Richter and Matson (1968) also found somewhat anomalous amounts of molybdenum (6 to 11 ppm) in stream sediments collected on or near the dike.
|Geologic map unit||(-144.012190025537, 62.7796107274411)|
|Mineral deposit model||Placer Au (Cox and Singer, 1986; model 39a)|
|Mineral deposit model number||39a|
|Age of mineralization||Holocene placer.|
|Workings or exploration||The area was prospected in the mid 1930s. Boulder Creek is almost certainly one of two unnamed gold-bearing creeks described briefly by Moffit (1938, p. 50-51) as 'two short streams that flow eastward from the divide at the head of Grubstake Creek into Porcupine Creek carry sufficient gold to encourage prospecting.' The other unnamed east-flowing auriferous creek is almost certainly Slope Creek (GU020). Moffit (1954, p. 195) also refers to easterly flowing, gold-bearing streams in the vicinity, one of which is probably Boulder Creek. Richter (1966) noted prospecting or small-scale placer mining in Boulder Creek.|
|Indication of production||Yes; small|
|Production notes||Probably some gold was recovered during prospecting activities at the head of Boulder Creek.|
Additional commentsThe association of stream sediment samples with anomalous gold and molybdenum near the elongate diorite pluton suggests that the intrusive and its contacts should be prospected for lode occurrences of gold and other metals.
Cobb, E.H., 1979, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Gulkana quadrangle, Alaska: U.S. Geological Survey Open-File Report 79-1247, 36 p.
MacKevett, E.M., Jr., and Holloway, C.D., 1977, Map showing metalliferous and selected non-metalliferous mineral deposits in the eastern part of southern Alaska: U.S. Geological Survey Open-File Report 77-169-A, 99 p., 1 sheet, scale 1:1,000,000.
Moffit, F.H., 1938, Geology of the Slana-Tok district, Alaska: U.S. Geological Survey Bulletin 904, 54 p.
Moffit, F.H., 1954, Geology of the eastern part of the Alaska Range and adjacent area: U.S. Geological Survey Bulletin 989-D, p. 65-218.
Richter, D.H., 1966, Geology of the Slana district, southcentral Alaska: Alaska Division of Geological and Geophysical Surveys Geological Report 2l, 54 p., 3 sheets, scale 1:63,360.
Richter, D.H., and Matson, N.A., Jr., 1968, Distribution of gold and some base metals in the Slana area, eastern Alaska Range, Alaska: U.S. Geological Survey Circular 593, 20 p.
|Reporters||W.T. Ellis (Alaska Earth Sciences), C.C. Hawley (Hawley Resource Group), and W.J. Nokleberg (U.S. Geological Survey)|
|Last report date||12/20/2000|