|Quadrangle map, 1:250,000-scale||TC|
|Quadrangle map, 1:63,360-scale||C-1|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||The Bluff prospect is located on a mountaintop in sections 10 and 11, T. 21 N., R. 20 E., of the Copper River Meridian. It is location 9 of Singer and others (1976), and location 4 of Eberlein and others (1977). The block of claims containing Bluff is adjacent to the west boundary of the Taurus prospect (TC027) block of claims, although the centers of prospecting activity for the two deposits do not adjoin. The geographic coordinates are the approximate center of prospecting activity at Bluff. The location is accurate to within 2 to 3 miles.|
Geologic descriptionThe Bluff prospect contains disseminated pyrite, chalcopyrite, molybdenite, tourmaline, and magnetite within high-level porphyritic quartz monzonite and granodiorite intrusions. The intrusions are of mid-Cretaceous to early Tertiary age (Foster, 1970). The intrusions also show evidence of strong hydrothermal alteration. Numerous faults and dikes are found in the area (Singer and others, 1976). The prospect was explored by surface sampling, diamond drilling, and geophysics in the early 1970s by Cities Services Mineral Corp. (David Hedderly-Smith, oral communication, 1998). The regional geology of the prospect consists of Precambrian-Paleozoic biotite gneiss and schist of amphibolite grade (Foster, 1970). The prospect also lies within the eastern portion of the Y1 subterrane of the Yukon-Tanana terrane (Foster and others, 1994).
|Geologic map unit||(-141.482236067469, 63.6196790910091)|
|Mineral deposit model||Porphyry Cu (Cox and Singer, 1986; model 21a)|
|Mineral deposit model number||21a|
|Age of mineralization||Mid-Cretaceous to early Tertiary, based on other deposits in the area (Mosquito: TC015).|
|Alteration of deposit||Strong hydrothermal alteration (Singer and others, 1976).|
|Workings or exploration||Explored by surface sampling, diamond drilling, and geophysics by Cities Services Mineral Corp. in the early 1970s (Singer and others, 1976). There has probably been more exploration in recent years. The Bluff prospect was also staked in 1987 by Resource Associates of Alaska, but was dropped two years later.|
|Indication of production||None|
Additional commentsSee also Mosquito (TC015) and Peternie (TC022) prospects.
Cobb, E.H., and Eberlein, G.D., 1980, Summaries of data on and lists of references to metallic and selected nonmetallic mineral deposits in the Big Delta and Tanacross quadrangles, Alaska: U.S. Geological Survey Open-File Report 80-1086, 77 p.
Eberlein, G.D., Chapman, R.M., Foster, H.L., and Gassaway, J.S., 1977, Map and table describing known metalliferous and selected nonmetalliferous mineral deposits in central Alaska: U.S. Geological Survey Open-File Report 77-168-D, 132 p., 1 sheet, scale 1:1,000,000.
Foster, H.L., 1970, Reconnaissance geologic map of the Tanacross quadrangle, Alaska: U.S. Geological Survey Miscellaneous Geological Investigations Map I-593, 1 sheet, scale 1:250,000.
Foster, H.L., and Keith, T.E.C., 1994, Geology of the Yukon-Tanana area of east-central Alaska: in Plafker, G. and Berg, H.C., eds, The geology of North America, vol. G-1, The geology of Alaska: Geological Society of America, p. 205-240.
Nokleberg, W.J., Bundtzen, T.K., Berg, H.C., Brew, D.A., Grybeck, D.J., Robinson, M.S., Smith, T.E., and Yeend, W., 1987, Significant metalliferous lode deposits and placer districts of Alaska: U.S. Geological Survey Bulletin 1786, 104 p., 2 plates, scale 1:5,000,000.
|Reporters||C.E. Cameron (ADGGS)|
|Last report date||4/13/1999|