|Quadrangle map, 1:250,000-scale||MH|
|Quadrangle map, 1:63,360-scale||A-6|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||Prospects in the Copper Knob block of the Clearwater Mountain claims (G.A. Moerlein, written communication, 1980) are in a steep, east-flowing creek that was called Copper Creek by Clautice and others (1989). Copper Creek is tributary to locally named Honey Creek, a tributary of the West Fork Maclaren River. The location is at the approximate center of a group of mineral deposits exposed along Copper Creek, at an elevation of about 4,800 feet in the approximate center of the SW1/4 section 29, T. 19 S., R. 5 E., Fairbanks Meridian. The location is accurate as the center of a group of deposits aligned along Copper Creek. The site corresponds approximately to the Honey claim prospects of Kurtak and others (1992, p. 147-149, locality A28) and represents occurrences 5 to 9 of Clautice and others (1989).|
The rocks in the area are metabasalt and related rocks of the Nikolai Greenstone of Late Cretaceous age thrust-faulted against argillite, slate, and limestone of uncertain age. Possibly Cretaceous or early Tertiary felsic dikes intrude the layered rocks. Layered rocks are intruded by a hornblende pyroxene sill near deposits (occurrences) 6 and 7 (Clautice and others, 1989; Kurtak and others, 1992).
Mineralization in the Copper Creek (informal name) area is complex: it includes skarn, mineralized dikes and shear zones, and quartz veins. The deposits contain gold, silver, copper, molybdenum, and tungsten (Clautice and others, 1989; Kurtak and others, 1992). Primary metallic minerals of the area include arsenopyrite, chalcopyrite, molybdenite, pyrite, tetrahedrite, and possibly scheelite and tennantite. The rocks are locally gossanized or stained with malachite.
Mineral deposits (occurrences) 6 to 9 of Clautice and others (1989) are clustered in a small part of the area. A thin high-grade chalcopyrite-bearing zone assayed 1,500 parts per billion (ppb) gold, 85.4 parts per million (ppm) silver, and more than 1 percent copper (deposit 6). Another thin (4 to 5 inch) quartz-epidote vein contains 8,710 ppm copper and 460 ppb gold (deposit 5). Samples collected from a 300-foot-long 3-foot-thick quartz-carbonate zone at the base of a gabbroic sill contain from 350 to 540 ppb gold (deposit 7). Other nearby mineral occurrences consist of disseminated chalcopyrite-pyrite-molybdenite in felsic dike rock and auriferous massive pyrite.
Private studies also indicate substantial mineralization in the area. In 1980, R.A. Blakestad and G.A. Moerlein examined and mapped the property, respectively, for Mankomen Exploration Company and for Occidental Minerals. According to them, the most significant occurrence is a strongly pyritized fault zone as much as 15 feet wide; the zone strikes west-northwest in Copper Creek and can be traced from about 4,700 feet to 5,000 feet in elevation and for 500 feet on strike. The area is immediately east of deposits (occurrences) 6 to 9 of Clautice and others (1989). Five samples collected from the pyritic zone ranged from 0.1 to 6 ppm gold and averaged 2.7 ppm gold (G.A. Moerlein, written communication, 1980). Moerlein believed that some of the rock previously mapped as gabbro was actually actinolite skarn. Probably the same pyritic zone recognized by Blakestad and Moerlein was also sampled and found auriferous by Anaconda Minerals Company in 1980 (Ellis, 1980).Significant mineralization was also reported in roughly the same area by the U.S. Bureau of Mines (Kurtak and others, 1992), although the precise location from which the Bureau samples were taken is unknown. They reported pyrite, chalcopyrite, arsenopyrite, tetrahedrite, and possibly tennantite from quartz veins and skarn. An 8-foot channel sample collected across a 100-foot-long skarn zone assayed 1.81 percent copper, 1.86 ounce silver per ton, and 340 ppm tungsten. A 7-foot-long sample collected across a quartz breccia zone traceable for at least 500 feet on strike assayed 0.06 ounce of gold per ton, 0.57 ounce of silver per ton, and 200 ppm tungsten (Kurtak and others, 1992, p. 147-149). This occurrence may be the pyritic zone recognized and sampled by Blakestad and Moerlein.
|Geologic map unit||(-146.834168303136, 63.2350604669875)|
|Mineral deposit model||Skarn, mineralized shear zone, and vein deposits; polymetallic in character. Cu skarn and polymetallic veins (Cox and Singer, 1986; models 18b and 22c).|
|Mineral deposit model number||18b, 22c|
|Age of mineralization||Younger than Late Triassic; probably Cretaceous or early Tertiary related to emplacement of felsite and mafic igneous rocks.|
|Alteration of deposit||Quartz-carbonate alteration; skarn replacement.|
|Workings or exploration||The area has been explored by shallow test pits. The Pat claims were located in the area in 1972-74; the Honey claims were located in 1979 (Kurtak and others, 1992). George A. Moerlein (written communication, 1980) mapped the prospects in the Copper Knob block of the Clearwater Mountain claims of Mankomen Exploration Company. The area was also visited and sampled by Anaconda Mineral Company in 1980 (Ellis, 1980).|
|Indication of production||None|
Additional commentsWork by private companies and government agencies suggests a strongly mineralized area; trenching and drilling were recommended by the U.S. Bureau of Mines (Kurtak and others, 1992, p. 148).
Clautice, K.H., Smith, T.E., Pessel, G.H., and Solie, D.N., 1989, Geology and mineral occurrences, upper Clearwater Creek area, Mt. Hayes A-6 quadrangle, Alaska: Alaska Division of Geological and Geophysical Surveys Public-data File 89-18, 14 p., 2 sheets, scale 1:24,000.
Ellis, W.T., 1980, 1980 Alaska Range Project: Anaconda Copper Co., Anchorage, Alaska, 33 p.
|Reporters||W.T. Ellis (Alaska Earth Science), C.C. Hawley (Hawley Resource Group), and W.J. Nokleberg (USGS)|
|Last report date||8/2/2001|