National Geochronological Database sample #219

Outcrop or artificial surface exposure, Biotite gneiss

Geographic location
-106.15, 41.3
106° 9' " W, 41° 18' " N
Albany county, WY
Centennial 1:24,000 scale map quadrangle
Accurate to within 5 minute (~5 miles)
WEST OF CENTENNIAL
Source of sample Outcrop or artificial surface exposure
Rock name Biotite gneiss
Laboratories Lamont (Columbia University)
Compiler name Marvin, R.F.
Date compiled 1974 07
Precision of location Accurate to within 5 minute (~5 miles)
Location comment WEST OF CENTENNIAL
Bibliographic reference Giffin, C.E., and Kulp, J.L., 1960, Potassium-argon ages in the Precambrian basement of Colorado: Geological Society of America Bulletin, v. 71, p. 219-222
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Geologic map unit -106.15, 41.3
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K-Ar age determinations

Age estimate 1,497.85 ± 60Ma
minimum age of metamorphic crystallization
Type of analysis conventional K-Ar
Rock or mineral analyzed biotite
Analytical details
Lab sample ID PUF-27B
Decay constants 4.72E-04, 0.584E-04, 1.19E-04*
K2O concentration 9.26 %
Radiogenic 40Ar concentration 311.2
Radiogenic Ar 97 %