|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||
The Lloyd prospect (Cobb, 1980 [OFR 80-363]) is in the canyon of the East Fork of Glen Creek, about 1500 feet due north of the confluence of the East and West forks of Glen Creek. The location is accurate within 500 feet.The prospect corresponds to number 21 of Cobb (1972 [MF 366]), 52 of Bundtzen, Smith, and Tosdal (1976), 56 of Bundtzen (1981), 239 of Hawley and Associates (1978), and 77 of Thornsberry, McKee, and Salisbury (1984).
The country rocks in the area of the Lloyd prospect are metachert (quartzite?) and garnet-quartz-muscovite schist of the upper Precambrian Birch Creek Schist (Bundtzen, 1981). The strata dip gently north and form asymmetric recumbent folds that plunge about S 80 W at a low angle (Thornsberry, McKee, and Salisbury, 1984, v. 2, occurrence 77).
The deposit consists of stratiform sulfide minerals concentrated in bands up to about 1/2 inch thick in a metachert layer as much as 3 feet thick. The sulfide-rich layers appear to thicken in fold crests. Sphalerite is the most abundant metallic mineral. It is accompanied by pyrite and lesser amounts of chalcopyrite, galena, and magnetite (Bundtzen, 1981). Outcrops are coated with azurite, malachite, and smithsonite. A 5-foot channel sample of a section thickened by folding assayed about 0.15 ounce of silver per ton, 2.2 percent zinc, 0.355 percent copper, and 0.07 percent lead. A selected sample of the richest material on the dump assayed 0.85 ounce of silver per ton, 5.6 percent zinc, 1.1 percent copper, and 0.215 percent lead (Thornsberry, McKee, and Salisbury, 1984, v. 2, occurrence 77). Bundtzen (1981) reported that another selected sample assayed 0.01 ounce of gold per ton.This stratabound deposit predates recumbent folding of the Birch Creek Schist. It appears to be a zinc-rich, syngenetic, volcanogenic deposit of late Precambrian age.
|Geologic map unit||(-150.744881875657, 63.5559982880797)|
|Mineral deposit model||Stratabound base-metal sulfide deposit, possibly of exhalative origin.|
|Age of mineralization||Possibly late Precambrian, the protolith age of the Birch Creek Schist.|
|Alteration of deposit||Oxidation of copper and zinc minerals.|
|Workings or exploration||The Lloyd prospect explored by a 24-foot-long tunnel before 1916 (Capps, 1919). Very little work has been done since then.|
|Indication of production||None|
Additional commentsThe prospect 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., 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.
Hawley, C. C. and Associates, Inc, 1978, Mineral appraisal of lands adjacent to Mt. McKinley National Park, Alaska: U. S. Bureau of Mines Open-File Report 24-78, 275 p. (paged by sections).
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||5/3/2001|