|Quadrangle map, 1:250,000-scale||SV|
|Quadrangle map, 1:63,360-scale||C-2|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||The Tidewater prospect is on the steep, rocky, east shore of Surprise Bay in the southeast corner of the Seldovia C2 quadrangle. Surprise Bay is in the West Arm of Nuka Bay. A short adit that was at sea level prior to the 1964 earthquake is now almost completely flooded at high tide (Richter, 1970). The adit was 42 feet in length but is less 25 feet long now due to wave action. This is Cobb's (1972, MF-397) location 27 and Richter's (1970) location 10. Cobb (1972, OFR 80-87) summarized the relevant references under the name Tidewater.|
Geologic descriptionThe prospect is in graywacke and interbedded slate of the Cretaceous Valdez Group (Richter, 1970). Prior to 1931, a 41 foot adit was driven on a vein that strikes N80E and dips 72S. The vein consists of a half-foot of sheeted quartz with scattered lens of arsenopyrite along the footwall and as much as four feet of barren quartz stockwork in the hanging wall. The country rock along the hanging wall is a graywacke that was brecciated prior to the introduction of the quartz stockwork. Assay values ranged from $38.90 to $18.00 per ton with gold at $20.67 per ounce (Pilgrim, 1933).
|Geologic map unit||(-150.482097801563, 59.509420197581)|
|Mineral deposit model||Low-sulfide, Au-quartz vein (Cox and Singer, 1986; model 36a)|
|Mineral deposit model number||36a|
|Age of mineralization||Tertiary; Boden and others (1991) report other veins in the district are about 55 m.y. old.|
|Alteration of deposit||None reported although, Borden and others (1991) report other veins in the Nuka Bay district show carbonization, sulfidization, sericitization, and silicification of the wall rock adjacent to the veins.|
|Workings or exploration||A 41 foot adit was driven in the 1930s. Richter (1970) took a single channel sample across the vein in the face of the drift, that assayed 6.5 ppm gold.|
|Indication of production||None|
|Production notes||Probably none.|
Borden, J.C., Goldfarb, R.J., Gent, C.A., Burruss, R.C., and Roushey, B.H., 1992 Geochemistry of lode-gold deposits, Nuka Bay district, southern Kenai Peninsula, in Bradley, D.C., and Dusel-Bacon, Cynthia, eds, Geologic studies in Alaska by the U.S. Geological Survey, 1991: U.S. Geological Survey Bulletin 2041, p. 13-21.
Cobb, E.H., 1972, Metallic mineral resources map of the Seldovia quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-397, 1 sheet, scale 1:250,000.
Cobb, E.H., 1979, Summary of references to mineral occurrences (other than minerals fuels and construction materials) in the Seldovia quadrangle, Alaska: U.S. Geological Survey Open-file Report 80-87, 47 p.
MacKevett, E.M., Jr., and Holloway, C.D., 1977, Map showing metalliferous and selected non-metalliferous mineral deposits in the eastern part of southern Alaska: U.S. Geological Survey Open-File Report 77-169-A, 99 p., 1 sheet, scale 1:1,000,000.
Pilgrim, E.R., 1933, Nuka Bay district, in Stewart, B. D., Making mining investigations and mine inspection in Alaska, biennium ending March 31, 1933: Alaska Territorial Department of Mines Annual Report 1933B, p. 26-51.
|Reporters||Jeff A. Huber (Anchorage)|
|Last report date||2/18/1999|