Quartz-Porphyry Prospect, Goodpaster Mining District, Southeast Fairbanks Census Area, Alaska, USAi

Regional Level Types
Quartz-Porphyry Prospect	Prospect
Goodpaster Mining District	Mining District
Southeast Fairbanks Census Area	Census Area
Alaska	State
USA	Country

The Quartz-Porphyry prospect is located within Doyon, Ltd. selected or conveyed land. For more information contact Doyon, Ltd., Fairbanks, Alaska.
Location: 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.
Geology: 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 Mouint 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.
Workings: 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.
Age: Intrusive rocks, probably related to the deposit, are of Mesozoic or Tertiary age (Foster, 1976).
Alteration: Local, well-developed porphyry-style alteration and mineralization in and peripheral to felsic dikes (Dashevsky and others, 1986).

Commodities (Major) - Mo; (Minor) - Cu, W
Development Status: None
Deposit Model: Porphyry Mo (Cox and Singer, 1986; model 21b).

Other Databases

Link to USGS - Alaska:	EA094

Other Regions, Features and Areas containing this locality

References