Quartz-Porphyry

Prospect, Inactive

Commodities and mineralogy

Main commodities Mo
Other commodities Cu; W
Ore minerals chalcopyrite; magnetite; molybdenite; pyrite
Gangue minerals quartz; sericite

Geographic location

Quadrangle map, 1:250,000-scale EA
Quadrangle map, 1:63,360-scale A-6
Latitude 64.2262
Longitude -143.8916
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Quartz-Porphyry prospect is in a small gully at an elevation of about 4,000 feet about 1.8 miles southwest of Mount Harper. The prospect is in the NW1/4 section 13, T. 8 S., R. 19 E., of the Fairbanks Meridian; the location is accurate within 1,000 feet. The Mount Harper area is locality 6 of Cobb (1972 [MF-393]). The Quartz-Porphyry prospect is located within Doyon, Ltd. selected or conveyed land.

Geologic setting

Geologic description

Several quartz porphyry dikes intrude a quartz-monzonite pluton and gneiss southeast of VABM Good in the headwaters of the Healy River (Dashevsky and others, 1986). Biotite from the nearby Mount Harper granite gives a 40Ar/39Ar plateau age of 105.8 +/- 0.4 Ma (Newberry and others, 1996). The Quartz-Porphyry prospect consists of well-developed porphyry-style alteration and mineralization within and peripheral to felsic dikes (Dashevsky and others, 1986). The dikes are limonite stained and contain rare disseminated molybdenite, pyrite, and chalcopyrite. Country rocks locally contain weak disseminated pyrite and chalcopyrite, stockworks and breccia with magnetite and silica flooding, and rare sub-horizontal molybdenite-rich quartz veins. These high-grade veins have low precious metal, tungsten, and tin values. A 1,000- by 500-foot zone with molybdenite, chalcopyrite, pyrite, and sericite spatially coincides with a slight magnetic low (WGM Inc., 1998 [DLR 98-10]). Several other molybdenum-tungsten prospects occur in the Mount Harper area, including VABM Good (EA092), Larsen Ridge (EA091), Airplane Ridge (EA093), and Section 21 (EA095).
Molybdenite in a quartz vein on the southern slope of Mount Harper was first reported by Chapin (1919). Anomalous tungsten, copper, and molybdenum values 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). The nearby Larsen Ridge skarn prospect (EA091) was discovered in 1977 on the ridge west of Mount Harper. In 1979, the Quartz-Porphyry prospect was discovered during an airborne magnetic survey and geologic mapping in the Mount Harper area by Union Carbide Corp. Additional detailed mapping and rock sampling were conducted in the area by Union Carbide Corp. in 1980.
Geologic map unit (-143.893919160116, 64.2258422895841)
Mineral deposit model Porphyry Mo (Cox and Singer, 1986; model 21b).
Mineral deposit model number 21b
Age of mineralization Intrusive rocks, probably related to the deposit, are of Mesozoic or Tertiary age (Foster, 1976).
Alteration of deposit Local, well-developed porphyry-style alteration and mineralization in and peripheral to felsic dikes (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 values 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). The nearby Larsen Ridge skarn prospect (EA091) was discovered in 1977 on the ridge west of Mount Harper. In 1979, the Quartz-Porphyry prospect was discovered during an airborne magnetic survey and geologic mapping in the Mount Harper area by Union Carbide Corp. Additional detailed mapping and rock sampling were conducted in the area by Union Carbide Corp. in 1980.
Indication of production None

Additional comments

The Quartz-Porphyry 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 10: Doyon, Ltd. Report 91-8g. (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).
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).
Union Carbide Corp., 1980, 1979 Lucky 13 project area report: Doyon, Ltd. Report 80-16 (Report held by Doyon, Ltd., Fairbanks, Alaska).
WGM Inc., 1977, Doyon Project, 1976 annual progress report, volume 1a, Blocks 1, 4, 5, 7, 8: Doyon, Ltd. Report 77-02a. (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