Unnamed Occurrence (ARDF - YA011; near Hill 5605 above Alsek River and within about 2 miles of the U.S.-Canada border), Yakutat District, Yakutat Borough, Alaska, USA

Proposed as an occurrence because of the width of the anomalous zone (100 feet) suggesting more detailed sampling could be warranted. The site is in Tongass National Forest and appears to be open for mineral location.
Location: Occurrence is at an elevation of about 3700 feet about 0.5 mile southeast of hill 5605 (section 17, T. 28 S., R. 43 E., of the Copper River meridian). It is 3 miles from the Alsek River and about 2 miles southwest of the U.S.- Canadian Border. Accuracy is within 0.15 mile. The occurrence is location number 2 of Cobb (1972).
Geology: The area is mainly underlain by schists of uncertain age, possibly Mesozoic or older, but also possibly metamorphosed Yakutat Group rocks of Jurassic and Cretaceous age. These rocks are cut by a granitic rock of Cretaceous or Tertiary age, part of an extensive pluton mostly exposed south of the large unnamed glacier south of the occurrence (MacKevett and Plafker, 1970). The mineral occurrence constitutes a hydrothermally altered zone about 100 feet wide in quartz diorite. A representative sample of the zone contained 0.08 ppm gold and 200 ppm copper.
Workings: Surface exposures only. MacKevett and Plafker (1970, table 1) reported 0.08 ppm gold and 200 ppm copper in sample 68APr85E. The occurrence was cited in Cobb (1972; 1979).
Age: Cretaceous or younger
Alteration: The occurrence is a hydrothermally altered zone, of unspecified type, in an intrusion.

Commodities (Major) - Au, Cu
Development Status: None
Deposit Model: Shear zone

References:
Cobb, E.H., 1972, Metallic mineral resources map of the Yakutat quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-408, 1 sheet, scale 1:250,000. Cobb, E.H., 1979, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Bering Glacier, Icy Bay, Middleton Island, and Yakutat quadrangles, Alaska: U.S. Geological Survey Open-File Report 79-1246, 41 p. MacKevett, E.M., Jr., and Plafker, G., 1970, Geochemical and geophysical reconnaissance of parts of the Yakutat and Mount St. Elias quadrangles, Alaska: U.S. Geological Survey Bulletin 1312-L, p. L1-L12 p.