National Geochronological Database sample #18430

Outcrop or artificial surface exposure, Quartz monzonite

Geographic location
-171.525, 63.452778
171° 31' 30" W, 63° 27' 10" N
AK
St. Lawrence C-6 1:63,360 scale map quadrangle
Accurate to within 0.1 minute (~500 feet)
Poovookpuk Mountain, St. Lawrence Island.
Source of sample Outcrop or artificial surface exposure
Rock name Quartz monzonite
Description Biotite quartz monzonite of the Sevuokuk pluton
Laboratories USGS Menlo Park
Compiler name Zartman, R.
Date compiled 1994 11
Precision of location Accurate to within 0.1 minute (~500 feet)
Location comment Poovookpuk Mountain, St. Lawrence Island.
Bibliographic reference Csejtey, B., Jr., Patton, W.W., Jr., and Miller, T.P., 1971, Cretaceous plutonic rocks of St. Lawrence Island, Alaska A preliminary report: U. S. Geological Survey Professional Paper 750-D, p. D68-D76.
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Geologic map unit -171.525, 63.452778
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K-Ar age determinations

Age estimate 91.3 ± 3Ma
age of intrusion
Type of analysis conventional K-Ar
Rock or mineral analyzed biotite
Analytical details
Lab sample ID 69Apa-219e (2)
Decay constants 4.72E-04, 0.585E-04, 1.19E-04
K2O concentration 7.98 %
Radiogenic 40Ar concentration 11.02
Radiogenic Ar 87 %