|Quadrangle map, 1:250,000-scale||PA|
|Quadrangle map, 1:63,360-scale||D-1|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||This site is the center of an area of about two square miles on the peninsula north of Saginaw Bay. More than one hundred claims were staked here in the late 1970's that covered sections 24, 25, and 36 of T. 57 S., R. 71 E. The location used for this site is at about the center of this area which is near the center of section 25.|
These occurrences are part of a group of similar deposits (PA021 to PA031) that are scattered along the south shore of Saginaw Bay, on the peninsula north of Saginaw Bay, and on the Keku Islands. They occur in a heterogeneous section of unmetamorphosed volcanic, carbonate, and clastic rocks that vary in age from Silurian to Triassic (Muffler, 1967). The mineralization generally consists of veins, veinlets, and irregular pods that contain base metals and barite (Still and others, 2002). There are no plutonic rocks in the immediate vicinity; however, the sedimentary rocks are cut by scattered gabbro dikes. The origin of the deposits is uncertain although most appear to be epigenetic. Various origins have been proposed including that they are remobilized massive-sulfide deposits, that they are related to a buried intrusive, or that they are Mississippi-Valley-type deposits.
The rocks in the area include outcrops of the following formations: 1) felsic to mafic volcanic rocks of the Triassic Keku Volcanics; 2) oolitic limestone of the Triassic Cornwallis Limestone; 3) white limestone, dolomite, and chert of the Permian Pybus Formation; and 4) crinoidal limestone of Carboniferous age (Muffler, 1967).These barite and/or base-metal occurrences were probably discovered in the 1920s but there is little specific information about them and their location is vague (Buddington, 1925). In 1978 and 1979, Mapco Inc. staked 108 claims for lead and zinc; the claims covered about 2 square miles in the center of the peninsula north of Saginaw Bay (Hedderly-Smith, 1993; Still and others, 2002). They drilled one hole in the west-central part of section 24, T. 57 S., R. 71 E., but there is no other information about their work. Still and others (2002) investigated the general area and collected several samples but none has significant metal values.
|Geologic map unit||(-134.161991944253, 56.8977152265301)|
|Mineral deposit model||Insufficient information on this specific area.|
|Age of mineralization||The host rocks vary in age from Carboniferous to Triassic and the mineralization is younger.|
|Workings or exploration||These barite and/or base-metal occurrences were probably discovered in the 1920s but there is little specific information about them and their location is vague (Buddington, 1925). In 1978 and 1979, Mapco Inc. staked 108 claims for lead and zinc; the claims covered about 2 square miles in the center of the peninsula north of Saginaw Bay (Hedderly-Smith, 1993; Still and others, 2002). They drilled one hole in the west-central part of section 24, T. 57 S., R. 71 E., but there is no other public information about their work.|
|Indication of production||None|
Additional commentsMAS number: 0021160015.
Buddington, A.F., 1925, Mineral investigations in southeastern Alaska: U.S. Geological Survey Bulletin 773-B, p. 71-139.
Cobb, E.H., 1972, Metallic mineral resources map of the Port Alexander quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-464, 1 sheet, scale 1:250,000.
Cobb, E.H., 1978, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Port Alexander quadrangle: U.S. Geological Survey Open-File Report 78-787, 33 p.
Hedderly-Smith, D.A., 1993, Report of the 1992 field season, Sealaska minerals reconnaissance report: Unpublished report, p. 92-114. (Report held by the Sealaska Corporation, Juneau, Alaska.)
Muffler, L.J.P., 1967, Stratigraphy of the Keku Islets and neighboring parts of Kuiu and Kupreanof Islands, southeastern Alaska: U.S. Geological Survey Bulletin 1241-C, p. C1-C52.
Still, J.C., Bittenbender, P.E., Bean, K.W., and Gensler, E.G., 2002 Mineral assessment of the Stikine area, central Southeast Alaska: U.S. Bureau of Land Management Technical Report 51, 560 p.
|Reporters||Donald J. Grybeck (U.S. Geological Survey)|
|Last report date||2-Jan-05|