Sample: DT88-1A

Sample ID:	DT88-1A ^[1]
Station ID:	DT88-1
AT Num:
Volcano:	Recheshnoi
Possible source:
Eruption:
Collector:	Turner, D. L.
Date sampled:	1988-00-00
Sample type 1:	Other
Color:
Final unit:
Text Description:	from plutonic rock unit Tdb, collected at the east side of Geyser Bight yielded concordant biotite and hornblende ages (K-Ar) of 9.64 +/- 0.29 and 9.40 +/- 0.28 Ma, respectively. These concordant ages indicate that the dated pluton had a simple cooling history; it cooled through the argon-blocking temperatures for hornblende and biotite (from 530C +/- 40C to 280C +/-40C) at about 9.5 Ma. Cooling must have occurred in less than 300 ka (standard deviation of ages) for the ages to be concordant.
Sample Location:

References Cited

[1] Geology and geochemistry of the Geyser Bight Geothermal area, Umnak Island, Aleutian Islands, Alaska, 1992

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.

Alaska Volcano Observatory

Sample: DT88-1A

References Cited

[1] Geology and geochemistry of the Geyser Bight Geothermal area, Umnak Island, Aleutian Islands, Alaska, 1992