|Quadrangle map, 1:250,000-scale||UK|
|Quadrangle map, 1:63,360-scale||A-2|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||This site is located near Geyser Creek on Umnak Island, approximately 3 miles southeast of Geyser Bight. Simpson's (1986) location of this site is vague and it could correspond to locations G or L which are mapped as clusters of hot-springs (Nye and others, 1992). The location is probably accurate to within 2 miles.|
Geothermal activity at this site is indicated by a 800 x 2000 foot color anomaly (Simpson, 1986). The rocks here consist of propylitized andesitic flows, tuffs, and volcaniclastics of Pleistocene age. The altered rocks exhibit local zones of intense argillization and weak silicification. The clay zones contain up to 2 percent disseminated pyrite.
Nye and others (1992) report dioritic and monzonitic plutons at low elevations on the east and west walls of the lower half of Geyser Creek valley, and they speculate that the plutons may host the geothermal reservoir system.Analyses of 20 rock samples indicated values up to 150 ppm arsenic, 0.58 ppm gold, 1.25 ppm mercury, and 0.2 ppm silver (Simpson, 1985, table 11, pg. 38). In general, the only rocks which contain gold are those which exhibit pyritization and moderate silicification. There does not appear to be any lateral or vertical zonation of the metals.
|Geologic map unit||(-168.502008930307, 53.1990663276063)|
|Mineral deposit model||Hot-spring Au-Ag (Cox and Singer, 1986; model 25a)|
|Mineral deposit model number||25a|
|Age of mineralization||Quaternary.|
|Alteration of deposit||The volcanic rocks exhibit regional propylitic alteration and local intense argillic alteration and weak silicification. The clay zones contain up to 2 percent pyrite and thin, discontinuous quartz veins.|
|Workings or exploration||Twenty samples collected by Kennecott were found to contain 8 to 150 ppm arsenic, 0.005 to 0.58 ppm gold, 0.005 to 1.25 ppm mercury, and 0.2 to 0.6 ppm silver (Simpson, 1986).|
|Indication of production||None|
Additional commentsThis site is on land selected by the Aleut Native Corporation.
Nye, C.J., Motyka, R.J., Turner, D.L., and Liss, S.A., 1992, Geology and geochemistry of the Geyser Bight Geothermal area, Umnak Island, Aleutian Islands, Alaska: Alaska Division of Geological & Geophysical Surveys Report of Investigation 92-1, 85 p., 2 sheets, scale 1:24,000.
Simpson, D.F., 1986, Aleutian Islands project, 1985 final report: Kennecott-Alaska Exploration Company, 54 p. (Report held by the Aleut Native Corporation, Anchorage, Alaska).
|Reporters||S.H. Pilcher (Anchorage)|
|Last report date||1/27/2000|