|Quadrangle map, 1:250,000-scale||NM|
|Quadrangle map, 1:63,360-scale||D-2|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||This occurrence is about 0.8 mile south of the Tub Mountain prospect (NM018) near the head of Rulby Creek (NM016). The occurrence is at an elevation of 760 feet and is accurately located from Herreid (1970).|
This limonite occurrence is about 0.8 mile south of the Tub Mountain prospect (NM018). It is a few hundred feet across (Herreid, 1970) and one of several carbonate-hosted, iron-rich deposits in the area (NM014, NM014, NM017, NM018, and NM020). The limonite can be massive to granular, botryoidal, mammillary, or fibrous. The iron content ranges to as much as 59 percent in analyzed samples (Eakin, 1915 [B 622-I, p. 361-365]). Hematite, pyrolusite, and calcite are present locally.
This occurrence and other iron deposits of the Sinuk River area are at or near the base of massive marble whose protolith age is probably lower Paleozoic (Sainsbury, Hummel, and Hudson, 1972; Bundtzen and others, 1994). The deposits are locally controlled by high-angle faults or folds, but they are in general crudely stratabound within the basal massive marble or underlying calc-schist (Mulligan and Hess, 1965; Herreid, 1970). This stratigraphic interval also hosts base metal sulfide-fluorite-barite deposits at the Galena (NM130) and Quarry prospects (NM135).
The origin and age of the iron deposits of the Sinuk River area are uncertain. The deposits may be, in part, gossan developed on oxidized sulfide deposits (Eakin, 1915 [B 622-I, p. 361-365]; Mertie,1918 [B 662-I, p. 425-449]; Cathcart, 1922; Mulligan and Hess, 1965; Herreid, 1970). Several of the iron deposits, including American (NM014) and Monarch (NM017), are locally highly anomalous in zinc and lead. Arguing against a simple gossan origin is the paucity of diagnostic textures and structures in boxworks that would suggest derivation from specific sulfide minerals. Alternatively, these deposits could be hypogene iron oxide and carbonate deposits that are transitional to lead-zinc-barite deposits such as the Quarry (NM135).The age of the iron deposits of the Sinuk River area is most likely post-mid-Cretaceous because faults that crosscut mid-Cretaceous metamorphic rocks are an important control on them. A Late Cretaceous age for the iron deposits was suggested by Brobst and others (1971) because this is the age of fluorine-rich tin granites of northwestern Seward Peninsula (Hudson and Arth, 1983). The youngest possible age appears to be Early Tertiary, when deep weathering, sandstone-type uranium mineralization, and possibly karst formation occurred to the east in the Solomon quadrangle (Hudson, 1999).
|Geologic map unit||(-165.739737540278, 64.7716363294854)|
|Mineral deposit model||Carbonate-hosted, iron oxide deposit.|
|Age of mineralization||Late Cretaceous or Early Tertiary; post mid-Cretaceous metamorphism.|
|Alteration of deposit||Dolomitization and oxidation.|
|Workings or exploration||There may be small prospecting pits at this locality.|
|Indication of production||None|
Brobst, D.A., Pinckney, D.M., and Sainsbury, C.L., 1971, Geology and geochemistry of the Sinuk River barite deposits, Seward Peninsula, Alaska: U.S. Geological Survey Professional Paper 750-D, p. D1-D8.
Bundtzen, T.K., Reger, R.D., Laird, G.M., Pinney, D.S., Clautice, K.H., Liss, S.A., and Cruse, G.R., 1994, Progress report on the geology and mineral resources of the Nome mining district: Alaska Division of Geological and Geophysical Surveys, Public Data-File 94-39, 21 p., 2 sheets, scale 1:63,360.
Cathcart, S.H., 1922, Metalliferous lodes in southern Seward Peninsula: U.S. Geological Survey Bulletin 722-F, p. 163-261.
Cobb, E.H., 1972, Metallic mineral resources map of the Nome quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-463, 2 sheets, scale 1:250,000.
Cobb, E.H., 1978, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Nome quadrangle, Alaska: U.S. Geological Survey Open-File report 78-93, 213 p.
Herreid, G.H., 1970, Geology and geochemistry of the Sinuk area, Seward Peninsula, Alaska: Alaska Division of Mines and Minerals Geologic Report 36, 61 p., 3 sheets, scales 1:42,000 and others.
Hudson, T.L., 1999, Alaska Resource Data File, Solomon quadrangle: U.S. Geological Survey Open-File Report 99-573, 360 p.
Hudson, T.L., and Arth, J. G., 1983, Tin granites of Seward Peninsula, Alaska: Geological Society of America Bulletin, v. 94, p. 768-790.
Mertie, J.B., Jr., 1918, Lode mining and prospecting on Seward Peninsula, in Brooks, A.H., and others, Mineral resources of Alaska, report on progress of investigations in 1916: U.S. Geological Survey Bulletin 662, p. 425-449.
Mulligan, J.J., 1965, Examination of the Sinuk iron deposits, Seward Peninsula, Alaska, with a section by Hess, H. D.: U.S. Bureau of Mines Open-File Report 8-65, 34 p.
Sainsbury, C.L., Hummel, C.L., and Hudson, Travis, 1972, Reconnaissance geologic map of the Nome quadrangle, Seward Peninsula, Alaska: U.S. Geological Survey Open-File Report 72-326, 28 p., 1 sheet, scale 1:250,000.
|Reporters||C.C. Hawley and Travis L. Hudson|
|Last report date||10/22/1999|