|Quadrangle map, 1:250,000-scale||SB|
|Quadrangle map, 1:63,360-scale||D-4|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||This site is located on the shore of Shapka Island approximately 2 miles south of Perryville. It represents several samples collected on the shoreline around the island. The site is referred to as SBRGX-47 in Wilson and others (1988, locality 21). The location is accurate to within 1,200 feet.|
Geologic descriptionThis occurrence is in rocks mapped as Eocene to Oligocene Mashik Formation (Wilson and others, 1995). Potassium-argon dating of hornblende from leuco-basalt gave an age of 43 million years (Wilson and others, 1994). Sandstone and siltstone are cut by felsic and porphyritic hornblende andesite(?) or diorite dikes. Some of the dikes are sulfide-bearing (Wilson and others, 1988). A slightly altered hornblende diorite dike is cut by a shear zone or by fractures filled with carbonate or quartz veins. Rock samples are reported to be anomalous in antimony and arsenic.
|Geologic map unit||(-159.12999573232, 55.8862088254276)|
|Age of mineralization||Eocene or younger.|
|Alteration of deposit||Some of the dikes are described as 'altered'.|
|Workings or exploration||Rock samples 84ACe113-116, collected by the U.S. Geological Survey in the mid-1980s, were reported to be anomalous in antimony and arsenic (Wilson and others, 1988).|
|Indication of production||None|
Angeloni, L.M., Wilson, F.H., and Sutley, S.J., 1985, Map and tables showing preliminary rock geochemical data, Port Moller, Stepovak Bay, and Simonof Island quadrangles, Alaska: U.S. Geological Survey Open-File Report 85-470, 179 p., 1 sheet, scale 1:250,000.
Wilson, F.H., Detterman, R.L., Miller, J. W., and Case, J.E., 1995, Geologic map of the Port Moller, Stepovak Bay, and Simeonof Island quadrangles, Alaska: U.S. Geological Survey Miscellaneous Investigation Series Map I-2272, 1 sheet, scale 1:250,000.
Wilson, F.H., Shew, N., DuBois, G.D., and Bie, S.W., 1994, Sample locality map and analytical data for potassium-argon ages in the Port Moller, Stepovak Bay and Simeonof Island quadrangles, Alaska Peninsula, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-2155-E, 18 p., 1 map sheet, scale 1:250,000.
|Last report date||11/8/2000|