|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 in central Umnak Island along the drainage of Geyser Creek about midway between Geyser Bight and Russian Bay (Nye and others, 1992, locality H; Christie, 1974, anomaly 36?). Site location is accurate to within 1/2 mile.|
This site is an active geothermal area along Geyser Creek in which hot springs, fumaroles, and mud pots are common (Randolph and Ellis, 1989). Pleistocene volcanic flows, tuffs, and volcaniclastics of andesitic composition have been intensely argillized by the geothermal activity (Nye and others, 1992).
Four exploration companies have examined and sampled this site at various times. This sampling of the altered rocks has produced values of up to 418 ppm arsenic, 652 ppm copper, 0.64 ppm gold, 92 ppm lead, > 5 ppm mercury, 4 ppm molybdenum, 4.7 ppm silver, and 345 ppm zinc.Nye and others (1992) report that the thermal waters are rich in boron (60 ppm) and arsenic (6 ppm).
|Geologic map unit||(-168.452001405089, 53.209069090291)|
|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||Byers (1959) described the alteration as consisting of fine-grained aggregates of quartz, chlorite, pyrite, and adularia(?). Simpson (1985) and Randolph and Ellis (1989) described the alteration as advanced argillic with up to 10 percent pyrite. Randolph (1990) also noted silica seen locally as veinlets, vugs, and rare calcedonic stockworks.|
|Workings or exploration||
This site has been examined and sampled by Duval-Quintana, Kennecott, Amax, and Battle Mountain Exploration. Christie (1974) reported values of up to .02 ppm gold, 4 ppm molybdenum, 1.2 ppm silver, and 47 ppm zinc from 6 samples of altered rock. Nine samples collected by Kennecott contained up to 250 ppm arsenic, 0.2 ppm gold, and 2.8 ppm mercury (Simpson, 1986).
Randolph and Ellis (1989) sampled this site as well as a zone along a north-flowing tributary which flows into Geyser Creek at this site (named Fumarole Creek by Nye and others, 1992). They reported values in 20 samples of up to 418 ppm arsenic, 652 ppm copper, 638 ppb gold, 92 ppm lead, > 5 ppm mercury, 1.5 ppm silver, and 345 ppm zinc. Six samples of quartz plus clay gave values to up to 72 ppm arsenic, 186 ppb gold, 2.6 ppm mercury, and 4.7 ppm silver. A panned sample taken at the intersection of the two drainages contained 5 small colors and 2 samples of nearby altered rocks contained 140 and 638 ppb gold.Randolph and Ellis (1989) state that the samples collected by Amax were similar in value to those collected by Battle Mountain Exploration.
|Indication of production||None|
Simpson (1986) considered this an active system, still depositing gold and altering country rocks. He found no ore grade zones and concluded it was unlikely that a deposit of significant size exists at the site. Battle Mountain Exploration (Randolph and Ellis, 1989) located numerous geochemically anomalous areas within the occurrence, but essentially agreed with previous interpretations.This site is on land selected by the Aleut Native Corporation.
Byers, F.M., Jr., 1959, Geology of Umnak and Bogoslof Islands, Aleutian Islands, Alaska: U.S. Geological Survey Bulletin 1028-L, p. 267-369, 3 sheets, scales 1:63,360, 1:96,000, 1:300,000.
Christie, J.S., 1974, Aleut-Quintana-Duval 1974 joint venture, final report: Unpublished Quintana Minerals Corporation report, 24 p., 3 appendices, 2 maps. (Report held by the Aleut Corporation, Anchorage, Alaska.)
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.
Randolph, D.B., 1990, Unalaska, 1990 final report: Battle Mountain Exploration Company, 72 p. (Report held by the Aleut Native Corporation, Anchorage, Alaska).
Randolph, D.B., and Ellis, W.T., 1989, Unalaska project, 1989 final report: Battle Mountain Exploration Company, Alaska District, 41 p., 5 appendices, 11 plates, various scales. (Report held by the Aleut Corporation, Anchorage, Alaska.)
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|