Airplane Ridge

Prospect, Probably inactive

Commodities and mineralogy

Main commodities Mo; W
Other commodities Ag; Au; Cu; Sn
Ore minerals chalcopyrite; magnetite; molybdenite; pyrite
Gangue minerals gypsum; quartz

Geographic location

Quadrangle map, 1:250,000-scale EA
Quadrangle map, 1:63,360-scale A-6
Latitude 64.2287
Longitude -143.9312
Nearby scientific data Find additional scientific data near this location
Location and accuracy Airplane Ridge is a 1-mile-long north-south-trending ridge about 5,000 feet high about 2.7 miles west of Mount Harper, at the headwaters of the Healy River. Airplane Ridge is not labeled on the U.S. Geological Survey topographic map of the Eagle A-6 quadrangle (1956). The coordinates are the approximate center of the prospect, near the southwest corner of section 11, T. 8 S., R. 19 E., of the Fairbanks Meridian; he location is accurate within 1,000 feet. The Mount Harper area is locality 6 of Cobb (1972 [MF-393]). The Airplane Ridge prospect is located within Doyon, Ltd. selected or conveyed land.

Geologic setting

Geologic description

Biotite gneiss, amphibolite, and minor marble crop out at the north and south end of Airplane Ridge; intrusive rocks form the center of the ridge (U.S. Bureau of Mines, 1995). Biotite from the nearby Mount Harper granite gives a 40Ar/39Ar plateau age of 105.8 +/- 0.4 Ma (Newberry and others, 1996). On Airplane Ridge, two breccia bodies parallel a quartz-porphyry dike that trends north-south (Dashevsky and others, 1986). The breccia bodies are 1,100 feet long and 15 to 50 feet wide. Outcrops of breccia and quartz-porphyry have low metal values, but float samples have anomalous molybdenum, as much as 0.23 ounce of silver per ton, as much as 675 ppm tungsten, as much as 22 ppm tin, and as much as 0.01 ounce of gold per ton. Breccia clasts are predominantly quartz porphyry with lesser chalcedony and quartz monzonite. The matrix is vuggy quartz and chalcedony; later gypsum lines vugs. Locally the quartz porphyry contains limonite, magnetite, pyrite, and chalcopyrite. The breccia generally is not limonitic or mineralized. There is limited phyllic alteration of quartz porphyry adjacent to breccia. There are several other molybdenum-tungsten prospects in the Mt. Harper area, including VABM Good (EA092), Larsen Ridge (EA091), Quartz-Porphyry (EA094), and Section 21 (EA095). Muscovite from a quartz-wolframite vein at the Section 21 prospect and biotite from a granitic body adjacent to a skarn at Larsen Ridge (see EA091) give mid-Cretaceous 40Ar/39Ar-plateau ages (Newberry and others, 1998). The Airplane Ridge molybdenum-tungsten prospect is similar and probably mid-Cretaceous as well.
Molybdenite in a quartz vein on the southern slope of Mount Harper was first reported by Chapin (1919). Anomalous tungsten, copper, and molybdenum were found during a stream-sediment reconnaissance in the Mount Harper area by WGM Inc. in 1975; this was followed by geologic mapping and rock sampling in 1976 (Dashevsky and others, 1986). An airborne magnetic survey and geologic mapping were conducted in the Mount Harper area by Union Carbide Corp. in 1979, and the Airplane Ridge prospect was identified during detailed mapping and rock sampling in 1980.
Geologic map unit (-143.933519727869, 64.2283415897401)
Mineral deposit model Porphyry Mo (Cox and Singer, 1986; model 21b).
Mineral deposit model number 21b
Age of mineralization There are several other molybdenum-tungsten prospects in the Mount Harper area, including VABM Good (EA092), Larsen Ridge (EA091), Quartz-Porphyry (EA094), and Section 21 (EA095). Muscovite from a quartz-wolframite vein at the Section 21 prospect and biotite from a granitic body adjacent to a skarn at Larsen Ridge (EA091) give mid-Cretaceous 40Ar/39Ar-plateau ages (Newberry and others, 1996). The Airplane Ridge molybdenum-tungsten prospect is similar and probably mid-Cretaceous as well.
Alteration of deposit Limited phyllic alteration of quartz porphyry adjacent to breccia (Dashevsky and others, 1986).

Production and reserves

Workings or exploration Molybdenite in a quartz vein on the southern slope of Mount Harper was first reported by Chapin (1919). Anomalous tungsten, copper, and molybdenum were found during a stream-sediment reconnaissance in the Mount Harper area by WGM Inc. in 1975; this was followed by geologic mapping and rock sampling in 1976 (Dashevsky and others, 1986). An airborne magnetic survey and geologic mapping were conducted in the Mount Harper area by Union Carbide Corp. in 1979, and the Airplane Ridge prospect was identified during detailed mapping and rock sampling in 1980.
Indication of production None

Additional comments

The Airplane Ridge prospect is located within Doyon, Ltd. selected or conveyed land. For more information contact Doyon, Ltd., Fairbanks, Alaska.

References

References

Dashevsky, S.S., Nicol, D.L., and Bond, J., 1986, Mines, prospects, and geochemical anomalies on Doyon Limited regional overselection lands, Alaska, Blocks 1-8: Doyon, Ltd. Report 86-01a, 300 p. (Report held by Doyon, Ltd., Fairbanks, Alaska).
DiMarchi, J.J., Weglarz, T.B., Dickey, C.F., Laux, D.P., Smith, M.T., Toro, J., and Kurtz, J.P., 1991, Central Alaska Gold Co. 1990 annual report, Alaska field operations - Doyon option volume 1: Doyon, Ltd. Report 91-8a. (Report held by Doyon, Ltd., Fairbanks, Alaska).
DiMarchi, J.J., Weglarz, T.B., Dickey, C.F., Laux, D.P., Smith, M.T., Toro, J., and Kurtz, J.P., 1991, Central Alaska Gold Co. 1990 annual report, Alaska field operations - Doyon option volume 2, analytical results, geochemical results part A: Doyon, Ltd. Report 91-8b. (Report held by Doyon, Ltd., Fairbanks, Alaska).
DiMarchi, J.J., Weglarz, T.B., Dickey, C.F., Laux, D.P., Smith, M.T., Toro, J., and Kurtz, J.P., 1991, Central Alaska Gold Co. 1990 annual report, Alaska field operations - Doyon option volume 2, analytical results, geochemical results part B: Doyon, Ltd. Report 91-8c. (Report held by Doyon, Ltd., Fairbanks, Alaska).
DiMarchi, J.J., Weglarz, T.B., Dickey, C.F., Laux, D.P., Smith, M.T., Toro, J., and Kurtz, J.P., 1991, Central Alaska Gold Co. 1990 annual report, Alaska field operations - Doyon option volume 7 plates, Fortymile central, Fortymile south, mid-Yukon, Nikolai, and East Holy Cross blocks: Doyon, Ltd. Report 91-8d. (Report held by Doyon, Ltd., Fairbanks, Alaska).
Hughs, M.A., and Siems, P.L., 1981, 1980 Lucky 13 project area report: Doyon, Ltd. Report 81-03. (Report held by Doyon, Ltd., Fairbanks, Alaska).
WGM Inc., 1998, Veta property, 1997 annual report, volume 1: Doyon, Ltd. Report 98-10, 227 p. (Report held by Doyon, Ltd., Fairbanks, Alaska).
Reporters R.L. Flynn; M.B. Werdon
Last report date 5/1/2002