|Quadrangle map, 1:250,000-scale||MG|
|Quadrangle map, 1:63,360-scale||C-4|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||The Lone occurrence is located about 0.5 miles south of VABM Lone at an elevation of 2,500 feet (762 m) in the SE1/4 sec. 18, T. 28 N., R. 29 W., of the Seward Meridian. The reporter visited the site in 1982 and 1992.|
A leucocratic, biotite granite radiometrically dated at 71.0 Ma (Solie and others, 1991) intrudes Lower Ordovician deepwater carbonate of the Nixon Fork Subterrane (Decker and others, 1994). The intrusion created a 760 meter wide thermal aureole, which locally has formed hornfels and small, discontinuous pods of skarn. The skarns at the Lone occurrence consist of magnetite, epidote, undetermined amphibole, and weakly disseminated pyrite and chalcopyrite. The magnetite bearing skarns crop out over a 10 meter by 12 meter area (Bundtzen, Harris, and Gilbert, 1997).Selected analyses (2) of the skarn zones at the Lone occurrence contain up to 0.50 percent copper, 35.00 percent iron, and 4.7 grams/tonne silver.
|Geologic map unit||(-154.720269682478, 62.5093707216322)|
|Mineral deposit model||Copper-iron skarns (Cox and Singer, 1986; model 18b).|
|Mineral deposit model number||18b|
|Age of mineralization||Inferred to be related to the 71.0 Ma granite intrusion (Solie and others, 1991).|
|Alteration of deposit||Epidote.|
|Workings or exploration||Selected analyses from surface samples at the Lone occurrence contain up to 0.50 percent copper, 35.00 percent iron, and 4.7 g/tonne silver.|
|Indication of production||None|
Additional commentsSee Nixon Fork and Whirlwind skarn deposits (MD040, MD064, MD062) in Medfra quadrangle.
Bundtzen, T.K., Harris, E.E., and Gilbert, W.G., 1997, Geologic Map of the eastern McGrath quadrangle, Alaska: Alaska Division of Geological and Geophysical Surveys Report of Investigations 97-14, 34 p., 1 sheet, scale 1:125,000.
Decker, J., Bergman, S.C., Blodgett, R.B., Box, S.E., Bundtzen, T.K., Clough, J.G., Coonrad, W.L., Gilbert, W.G., Miller, M.L., Murphy, J.M., Robinson, M.S., and Wallace, W.K., 1994, Geology of southwestern Alaska, in Plafker, G. and Berg, H.C., eds., The Geology of Alaska: Geological Society of America DNAG, The Geology of North America, v. G-1, p. 285-310.
|Reporters||T.K. Bundtzen (Pacific Rim Geological Consulting)|
|Last report date||11/20/1998|