|Quadrangle map, 1:250,000-scale||MM|
|Quadrangle map, 1:63,360-scale||C-2|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||
Spruce Creek (Cobb, 1980 [OFR 80-363]) rises on the south flank of Spruce Peak and flows south-southeast for about two miles. The creek then flows southerly for about 1.5 miles, where it joins Willow Creek (MM107) to form Moose Creek (MM132). The location is where Spruce Creek crosses the boundary between sections 4 and 9, T. 16 S., R. 16 W., Fairbanks Meridian. This location is about a third of a mile above the point where the creek leaves the Kantishna Hills and flows on the broad glacio-fluvial plain on the north side of Moose Creek.The site is about in the center of resource block S-1 of Thornsberry, McKee, and Salisbury (1984, fig. K-3). It is location 52 of Cobb (1972 [MF 366]) and location 57 of MacKevett and Holloway (1977).
About the uppermost 3/4 mile of Spruce Creek cuts bedrock of the Spruce Creek sequence; below that, it cuts Birch Creek Schist (Bundtzen, 1981; Thornsberry, McKee, and Salisbury, 1984, fig. K-2). The part of the creek that trends northwest is controlled by a steep fault that cuts sharply across the Spruce Creek strata and the contact between Spruce Creek and Birch Creek rocks. The headwater region of the creek contains numerous lode deposits. Upper Spruce Creek is steep; it has a gradient of about 350 feet per mile in section 32 (T. 15 S., R. 16 W.), decreasing downstream to about 200 feet per mile. The steep upper creek contains thin deposits of angular, poorly-sorted gravel derived from country rock and quartz veins. The gold in placer deposits in upper Spruce Creek is rough, crystalline, and some has adhering vein quartz (Prindle, 1907).
The lowest mile of Spruce Creek flows over an alluvial fan lying on bouldery glacial outwash or till. Irregular stream channels cut in the fan contain relatively angular gravel that carries a little gold. A small placer operation in 1983, conducted more or less as a test, mined gravel grading 0.005 ounce (0.004 fine ounce) of gold per cubic yard (Levell, 1984, v. 2). Gravel in a test excavation upstream graded about 0.005 ounce of gold per cubic yard in a 9-foot-thick gravel section. A 2-foot-thick part of this section graded about 0.011 ounce of gold per cubic yard.Successful mining operations farther upstream probably processed richer gravel. Bundtzen, Smith, and Tosdal (1976, p. 14) describe a 1975 operation that processed several tens of thousands of cubic yards of gravel at a site about 2 1/2 miles above the mouth of the creek.
|Geologic map unit||(-150.668379276074, 63.5487003797164)|
|Mineral deposit model||Au-PGE placer (Cox and Singer, 1986; model 39a).|
|Mineral deposit model number||39a|
|Age of mineralization||Holocene.|
|Workings or exploration||Mining in the upper canyon of Spruce Creek was in progress in 1906 (Prindle, 1907). A probably rich, thin and narrow placer deposit was almost completely mined out in one or two seasons. There was one operation on the creek in 1922 (Davis, 1923). The later history of creek is poorly known. There was one substantial operation in 1975 (Bundtzen, Smith, and Tosdal, 1976), and a small, test operation in 1983 (Levell, 1984, v. 2). There has been no substantial mining since about 1985.|
|Indication of production||Yes; small|
|Reserve estimates||Levell (1984) proposed that uppermost Spruce Creek (block S-1) contains a total of 315,000 cubic yards--in both claimed and unclaimed ground--of alluvial gravel carrying a little gold. Assuming a grade range of 0.0001 to 0.0051 ounce of gold per cubic yard, there is a remaining resource of 32 to 1566 ounces of gold. Block S-2, on the lower part of the creek, contains about 285, 000 cubic yards of material. Assuming the same range of grades, its remaining gold resource is 28 to1454 ounces.|
|Production notes||Production began in 1906 and continued intermittently through 1983. Cobb (1977 [OFR 77-168B]) proposed that production was less than 1000 ounces, but later thought that, in view of the operation in 1975, the figure was too low (Cobb, 1980 [OFR 80-363]). Production was probably at least 1000 ounces.|
Additional commentsThe low grade of alluvium remaining in Spruce Creek reflects relatively complete extraction of a small, high-grade deposit in 1906-07. The operation in 1975 probably recovered much of the remaining high-grade material. The creek is in Denali National Park and Preserve.
Bundtzen, T.K., 1981, Geology and mineral deposits of the Kantishna Hills, Mt. McKinley quadrangle, Alaska: M. S. Thesis, University of Alaska, College, Alaska, 238 p.
Bundtzen, T.K., Smith, T.E., and Tosdal, R.M., 1976, Progress report--Geology and mineral deposits of the Kantishna Hills: Alaska Division of Geological and Geophysical Surveys Open-File Report AOF-98, 80 p., 2 sheets, scale 1:63,360.
Cobb, E. H., 1972, Metallic mineral resources map of the Mount McKinley quadrangle, Alaska: U. S. Geological Survey Miscellaneous Field Studies Map MF-366, 1 sheet, scale 1:250,000.
Cobb, E.H., 1977, Placer deposit map of central Alaska: U.S. Geological Survey Open-File Report 77-168-B, 64 p., 1 map, scale 1:1,000,000.
Cobb, E.H., 1980, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Mount McKinley quadrangle, Alaska: U. S. Geological Survey Open-File Report 80-363, 150 p.
Cox, D.P., and Singer, D.A., eds., 1986, Mineral deposit models: U.S. Geological Survey Bulletin 1693, 379 p.
Davis, J. A., 1923, The Kantishna region, Alaska, in Stewart, B. D., Annual Report of the Mine Inspector to the Governor of Alaska, 1922: Alaska Division of Geological and Geophysical Surveys AR-1922.
Levell, J. H., 1984, Appendix A, Placer, in 1983 Mineral Resource Studies: Kantishna Hills and Dunkle mine areas, Denali National Park and Preserve, Alaska: U. S. Bureau of Mines Open-File Report 129-84, Vol. 2, p. 1-219.
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.
Prindle, L.M., 1907, The Bonnifield and Kantishna regions, Alaska: U.S. Geological Survey Bulletin 314-L, p. 205-226.
Thornsberry, V. V., McKee, C. J., and Salisbury, W. G., eds, 1984, 1983 Mineral Resource Studies: Kantishna Hills and Dunkle Mine Areas, Denali National Park and Preserve, Alaska: U. S. Bureau of Mines Open-File Report 129-84. 3 Volumes: v. 1, Text; v. 2, Appendices; v. 3, Maps. Prepared by Salisbury & Dietz, Inc., Spokane, WA.
|Last report date||4/27/2001|