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)
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 %