National Geochronological Database sample #3640

Outcrop or artificial surface exposure, Granodiorite

Geographic location
-117.125, 40.541667
117° 7' 30" W, 40° 32' 30" N
Lander county, NV
Antler Peak 1:62,500 scale map quadrangle
Accurate to within 1 minute (~1 mile)
SW1/4 SEC. 22, T31N, R43E; ROADCUT IN COPPER CANYON AREA
Source of sample Outcrop or artificial surface exposure
Rock name Granodiorite
Description ALTERED GRANODIORITE OF COPPER CANYON AREA; MEDIUM- TO COARSE-GRAINED ALTERED PORPHYRITIC GRANODIORITE
Laboratories USGS Menlo Park
Compiler name Nichols, S.L.
Date compiled 1978 04
Precision of location Accurate to within 1 minute (~1 mile)
Location comment SW1/4 SEC. 22, T31N, R43E; ROADCUT IN COPPER CANYON AREA
Bibliographic reference Theodore, T.G., Silberman, M.L., and Blake, D.W., 1973, Geochemistry and Potassium-Argon Ages Of Plutonic Rocks In The Battle Mountain Mining District, Lander County, Nevada: U.S. Geological Survey Professional Paper 798A, A24pp.
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Geologic map unit -117.125, 40.541667
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K-Ar age determinations

Age estimate 39.42 ± 0.8Ma
age of intrusion
Type of analysis conventional K-Ar
Rock or mineral analyzed biotite
LESS THAN 1% CHLORITE; -60+100 MESH SAMPLE
Analytical details
Lab sample ID 9. (MB-18)
Decay constants 4.72E-04, 0.585E-04, 1.19E-04*
K2O concentration 8.54 %
Radiogenic 40Ar concentration 4.9
Radiogenic Ar 87 %