Saddle

The Saddle is a gold mine located in Alaska.

About the MRDS Data:

All mine locations were obtained from the USGS Mineral Resources Data System. The locations and other information in this database have not been verified for accuracy. It should be assumed that all mines are on private property.

Mine Info

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Site Name

Primary: Saddle

Commodity

Primary: Gold

Location

State: Alaska
District: Council

Land Status

Not available

Holdings

Not available

Workings

Not available

Ownership

Not available

Production

Not available

Deposit

Record Type: Site
Operation Category: Prospect
Operation Type: Unknown
Years of Production:
Organization:
Significant:

Physiography

Not available

Mineral Deposit Model

Model Name: Low-sulfide Au-quartz vein

Orebody

Not available

Structure

Not available

Alterations

Alteration Type: L
Alteration Text: Quartz veining; alteration minerals in the host schist include plagioclase, chlorite, carbonate, white mica, biotite, titanite, and tourmaline.

Rocks

Not available

Analytical Data

Not available

Materials

Ore: Arsenopyrite
Ore: Gold
Ore: Marcasite
Ore: Pyrite
Ore: Pyrrhotite
Gangue: Biotite
Gangue: Chlorite
Gangue: Fluorite
Gangue: Plagioclase
Gangue: Quartz
Gangue: Mica
Gangue: Titanite

Comments

Comment (Exploration): Status = Active?

Comment (Geology): Age = Mid-Cretaceous, the age of some other lode gold deposits on southern Seward Peninsula. At this prospect, a sample of vein white mica gave a Ar/Ar plateau date of 109.1 +/- 0.2 Ma and metamorphic white mica in the host schist gave Ar/Ar total gas dates of 122.6 +/- 0.4 Ma and 122.4 +/- 0.2 Ma (Ford and Snee, 1996).

Comment (Reference): Primary Reference = Ford and Snee, 1996

Comment (Workings): Workings / Exploration = Surface soil sampling and some diamond drilling by BHP-Utah International was done here about 1990.

Comment (Commodity): Gangue = carbonate

Comment (Geology): Geologic Description = The Saddle prospect is known from the work of Ford (1993) and Ford and Snee (1996). A large gold and arsenic anomaly in soils led to its discovery. Gold-bearing quartz veins are localized in extensional joints that strike easterly and dip moderately to the south in quartz-muscovite schist. The host schist is similar to that at the nearby Bluff (SO135), Swede Creek (SO133) and Koyana Creek (SO136) lode prospects. This schist is a band intercalated in Paleozoic marble (Herried, 1965; Mulligan, 1971; Till and others, 1986). The veins are discontinuous and commonly less than 3 inches thick. Gold grades are irregularly distributed; vein intersections up to 3.3 feet across contain up to 1.8 ounces Au per ton. Minerals identified in the veins include arsenopyrite, biotite, carbonate, chlorite, fluorite, marcasite, plagioclase, pyrite, pyrrhotite, quartz, titanite, and white mica. Alteration minerals in the host schist include plagioclase, chlorite, carbonate, white mica, biotite, titanite, and tourmaline. The white mica in the veins is muscovite and that in the host schist is phengite. A sample of vein white mica gave a Ar/Ar plateau date of 109.1 +/- 0.2 Ma and metamorphic white mica in the host schist gave Ar/Ar total gas dates of 122.6 +/- 0.4 Ma and 122.4 +/- 0.2 Ma (Ford and Snee, 1996). This age is similar to that for some other lode gold deposits on southern Seward Peninsula. The southern Seward Peninsula lode gold deposits formed as a result of mid-Cretaceous metamorphism (Apodoca, 1994; Ford, 1993, Ford and Snee, 1996; Goldfarb and others, 1997) that accompanied regional extension (Miller and Hudson, 1991) and crustal melting (Hudson, 1994). This higher temperature metamorphism was superimposed on high pressure/low temperature metamorphic rocks of the region.

Comment (Deposit): Model Name = Gold-bearing quartz veins along extension joints in quartz-mica schist; low sulfide-Au quartz vein (Cox and Singer, 1986; model 36a).

Comment (Commodity): Gangue = white mica

References

Reference (Deposit): Ford, R.C., 1993, Geology, geochemistry, and age of gold lodes at Bluff and Mt. Distin, Seward Peninsula, Alaska: Golden, Colorado School of Mines, Ph.D. dissertation, 302 p.

Reference (Deposit): Herreid, G.H., 1965, Geology of the Bluff area, Solomon quadrangle, Seward Peninsula, Alaska: Alaska Division of Geological and Geophysical Surveys Geological Report 10, 21 p., 1 sheet, scale 1:40,000.

Reference (Deposit): Till, A.B., Dumoulin, J.A., Gamble, B. ., Kaufman, D.S., and Carroll, P.I., 1986, Preliminary geologic map and fossil data, Soloman, Bendeleben, and southern Kotzebue quadrangles, Seward Peninsula, Alaska: U.S. Geological Survey Open-File Report 86-276, 10 p., 3 plates, scale 1:250,000.

Reference (Deposit): Apodoca, L. E., 1994, Genesis of lode gold deposits of the Rock Creek area, Nome mining district, Seward Peninsula, Alaska: Boulder, Colorado, University of Colorado, Ph.D. dissertation, 208 p.

Reference (Deposit): Ford, R.C., and Snee, L.W., 1996, 40Ar/39Ar thermochronology of white mica from the Nome district, Alaska: The first ages of lode sources to placer gold deposits in the Seward Peninsula: Economic Geology, v. 91, p. 213-220.

Reference (Deposit): Mulligan, J.J., 1971, Sampling gold lode deposits, Bluff, Seward Peninsula, Alaska, with a section on petrography by Walter L. Gnagy: U.S. Bureau of Mines Report of Investigations 7555, 40 p.

Reference (Deposit): Goldfarb, R.J., Miller, L.D., Leach, D.L., and Snee, L.W, 1997, Gold deposits in metamorphic rocks in Alaska, in Goldfarb, R.J., and Miller, L.D., eds., Mineral deposits of Alaska: Economic Geology Monograph 9, 482 p.

Reference (Deposit): Cobb, E.H., 1978, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Solomon quadrangle, Alaska: U.S. Geological Survey Open-File Report 78-181, 185 p.

Reference (Deposit): Miller, E.L., and Hudson, T.L., 1991, Mid-Cretaceous extensional fragmentation of a Jurassic-Early Cretaceous compressional orogen, Alaska: Tectonics, v. 10, p. 781-796.

Reference (Deposit): Hudson, T.L. 1994, Crustal melting events in Alaska, in Plafker, G., and Berg, H. C., eds., The Geology of Alaska: Boulder, Colorado, Geological Society of America, The Geology of North America, v. G-1, p. 657-670.

Reference (Deposit): Cobb, E.H., 1972, Metallic resources map of the Solomon quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-445, scale 1:250,000.

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