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Lucky Top

Prospect, Active

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Commodities and mineralogy

Main commodities Ag; Au; Cu; Fe; Pb; Sb; Zn
Ore minerals arsenopyrite; chalcopyrite; galena; gold; pyrite; pyrrhotite; stibnite; sphalerite
Gangue minerals ankerite; quartz

Geographic location

Quadrangle map, 1:250,000-scale HE
Quadrangle map, 1:63,360-scale A-1
Latitude 63.1889
Longitude -147.2498
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Lucky Top prospect is at an elevation of about 5,000 feet about 0.2 mile northwest of the top of Lucky Hill. It is about 0.5 mile south-southwest of the center of section 7, T. 20 S., R. 3 E., of the Fairbanks Meridian. The location is accurate.

Geologic setting

Geologic description

The Lucky Top prospect is one of four deposits that was explored by CanAlaska Resources Ltd. from 1983 to at least 1996 as the Rainbow Hill project. It and the nearby Gold Hill (HE209) Lucky Saddle (HE215), and TMC (HE211) prospects share a similar origin and general characteristics. The Rainbow Hill project is described in considerable detail by Adams (1996) and Freeman (2002) and most of what follows is based on their work.
The rocks in the area consist of folded Jurassic to Cretaceous argillite, graywacke, siltstone, and mafic tuff that were intruded by Tertiary and Cretaceous gabbro and diorite in small stocks and dikes (Smith, 1981). The rocks underwent lower-greenschist- to amphibolite-grade metamorphism in the Cretaceous and early Tertiary. The airborne geophysical data suggest that the Gold Hill/Lucky Top area that roughly coincides with the Rainbow Hill project is underlain by a shallow, structurally deformed meta-igneous complex. The regional structure is dominated by a set of east-trending thrust faults and cross-cutting high-angle faults. A set of northwest trending, high-angle faults and dikes associated with the mineralization is offset by northwest- and northeast-trending faults.
The mineralization in the Rainbow Hill project consists of zones of stacked sulfide-bearing, ankerite-quartz veins and stockworks that strike east and dip variably to the north and south. The sulfides in the veins and stockworks are mainly pyrite and arsenopyrite; minor amounts of pyrrhotite, chalcopyrite, galena, stibnite, and sphalerite occur widely as does visible gold. Abundant sulfides usually indicate high gold values. The auriferous zones typically have a central area of intense silicification, sericitization, and carbonatization, that weakens outward. Sericite from the veins has been dated at 57.6 to 63.1 Ma by argon-argon methods.
Although there had been some earlier work on the gold veins in the Gold Hill/Lucky Top area (Moffit, 1912; Ross, 1933; Tuck, 1938), the first extensive exploration in the area was in 1983 when CanAlaska began a program of surface mapping, outcrop sampling, soil geochemical surveys, trenching, and ground geophysical surveys.
The mineralization at the Lucky Top prospect consists of tourmaline-carbonate-quartz breccia with sparse sulfides; it is near the contact of a metamorphosed diorite intrusion. Grab samples from an old dump contained up to 0.11 ounce of gold per ton.
Geologic map unit (-147.252058855419, 63.188453647788)
Mineral deposit model Low-sulfide Au-quartz veins (Cox and Singer, 1986; model 36a).
Mineral deposit model number 36a
Age of mineralization About 60 Ma based on the age of sericite from the quartz veins.
Alteration of deposit The mineralization is associated with pervasive sericite-carbonate-quartz alteration; local hornfelsing and tourmalinization.

Production and reserves

Workings or exploration There was some early work on on the gold veins in the Gold Hill/Lucky Top area, notably a short adit on the Lucky Top prospect ( Moffit, 1912; Ross, 1933; Tuck, 1938). But the first extensive exploration in the area was in 1983 when CanAlaska began a program of surface mapping, outcrop sampling, soil geochemical surveys, trenching, and ground geophysical surveys. Some surface work was done on the Lucky Top prospect but no drilling.
Indication of production None

Additional comments

This vein is the probable source area of the placer gold and large nuggets in Lucky Gulch (HE207) below it.

References

MRDS Number A011321

References

Adams, D.D., 1996, A report on the Rainbox Hill claims: Unpublished Technical Report for CanAlaska Uranium Ltd., 72 p. (posted on www.sedar.com, May 6, 2008)
Clark, A.L., and Cobb, E.H., 1972, Metallic mineral resources map of the Healy quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-394, 1 sheet, scale 1:250,000.
Freeman, Curtis, 2002, Addendum to the report prepared by David D. Adams on the Rainbox Hill property: Unpublished Technical Report for CanAlaska Uranium Ltd., 8 p. (posted on www.sedar.com, May 6, 2008)
Moffit, F.H., 1912, Headwater regions of Gulkana and Susitna Rivers, Alaska, with accounts of the Valdez Creek and Chistochina placer districts: U.S. Geological Survey Bulletin 498, 82 p.
Ross, C.P., 1933, The Valdez Creek mining district, Alaska: U.S. Geological Survey Bulletin 849-H, p.425-468.
Smith, T.E., 1981, Geology of the Clearwater Mountains, southcentral Alaska: Alaska Division of Geological and Geophysical Surveys Geologic Report 60, 72 p., 3 sheets, scale 1:63,360.
Tuck, Ralph, 1938, The Valdez Creek mining district, Alaska, in 1936: U.S. Geological Survey Bulletin 897-B, p. 109-131.
Wiltse, M.A., and Reger, R.D., 1989, Geologic map of Gold Hill and Lucky Hill, Valdez Creek mining district, Healy A-1 quadrangle, Alaska: Alaska Division of Geological and Geophysical Surveys Public-Data File 89-5, scale 1:12,000, 1 sheet.
Reporters D.L. Stevens (Stevens Exploration Management Corporation), D.J. Grybeck (Port Ludlow, WA)
Last report date 6/5/2008