Spray Creek

Occurrence, Inactive

Commodities and mineralogy

Main commodities Cu
Other commodities Ag; Au; W
Ore minerals bornite; chalcopyrite; malachite; tetrahedrite
Gangue minerals carbonates; epidote; quartz

Geographic location

Quadrangle map, 1:250,000-scale MH
Quadrangle map, 1:63,360-scale B-6
Latitude 63.2912
Longitude -146.5544
Nearby scientific data Find additional scientific data near this location
Location and accuracy This lode occurrence is at an elevation of about 3,900 feet on the north side of Spray Creek, in the SW1/4SW1/4 section 2, T. 19 S., R. 6 E., Fairbanks Meridian. Mineralization probably extends into the eastern part of section 10 of the previously cited township and range. The location corresponds approximately to locality 24 on figure 4 of Cobb (1979 [OFR 79-238]); to locality 18 of Kaufman (1964); to locality A12 of Kurtak and others (1992); and possibly to McLaren Copper (Heiner and Porter, 1972, Kardex site number KX68-41). The location cited here is probably within 500 feet of locality A12 of Kurtak and others (1992).

Geologic setting

Geologic description

The occurrence is hosted in basaltic greenstone of the Nikolai Greenstone of Late Triassic age, a characteristic unit of the Wrangellia terrane (Nokleberg and others, 1982, 1991).
The basalt is well exposed in an incised lower canyon of Spray Creek. Randomly oriented shear zones, as much as 5 feet across, cut epidotized basalt. The shear zones can be traced for as much as 100 feet on strike. Mineralized quartz-carbonate veinlets in the shear zones contain bornite and tetrahedrite and are stained with malachite. Grab samples of vein material contain as much as 3.17 percent copper and 9 parts per million (ppm) silver; sample 1651 assayed 760 parts per billion gold and 145 ppm tungsten (Kurtak and others, 1992, table A12). Kaufman (1964, locality 18) earlier reported bornite and chalcopyrite in randomly oriented fractures on the steep north wall of the canyon.
Geologic map unit (-146.5566666797, 63.2907695712197)
Mineral deposit model Low-sulfide copper-bearing quartz-carbonate veins. Basaltic Cu (Cox and Singer, 1986; model 23).
Mineral deposit model number 23
Age of mineralization Probably Cretaceous or early Tertiary (see MH060).
Alteration of deposit Introduction of epidote into basaltic greenstone.

Production and reserves

Workings or exploration The area has been staked variously as the Tiny Tim, KAA, and MacLaren Copper claims nos. 1-4. Claims were first staked in 1955; one claim was located as recently as 1989 (Heiner and Porter, 1972; U.S. Bureau of Mines, 1973; Kurtak and others, 1992). There are no important workings.
Indication of production None

References

References

Heiner, L.E., and Porter, Eve, 1972, Alaska Mineral Properties, volume 2: University of Alaska, Mineral Industry Research Laboratory Report 24, 669 p.
U.S. Bureau of Mines, 1973, Alaska 1:250,000-scale quadrangle map overlays showing mineral deposit locations, principal minerals, and number and type of claims: U.S. Bureau of Mines Open-File Report 20-73, 95 overlays (updated in 1986, 1987).
Reporters W.T. Ellis (Alaska Earth Science), C.C. Hawley (Hawley Resource Group), and W.J. Nokleberg (USGS)
Last report date 7/31/2001