National Geochronological Database sample #3295

Outcrop or artificial surface exposure, Granodiorite

Geographic location
-116.694722, 40.308056
116° 41' 41" W, 40° 18' 29" N
Lander county, NV
Crescent Valley 1:62,500 scale map quadrangle
Accurate to within 1 minute (~1 mile)
SHOSHONE RANGE
Source of sample Outcrop or artificial surface exposure
Rock name Granodiorite
Description PORPHYRITIC GRANODIORITE
Laboratories USGS Menlo Park
Compiler name Nichols, S.L.
Date compiled 1978 02
Precision of location Accurate to within 1 minute (~1 mile)
Location comment SHOSHONE RANGE
Bibliographic reference McKee, E.H., and Silberman, M.L., 1970, Geochronology Of Tertiary Igneous Rocks In Central Nevada: Geological Society of America Bulletin, v. 81, p. 2317-2328.
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Geologic map unit -116.694722, 40.308056
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K-Ar age determinations

Age estimate 38.11Ma
age of intrusion
Type of analysis conventional K-Ar
REPLICATE POTASSIUM ANALYSES
Rock or mineral analyzed biotite
Analytical details
Lab sample ID 3
Decay constants 4.72E-04, 0.585E-04, 1.19E-04*
K2O concentration 7.99 %
Radiogenic 40Ar concentration 4.43
Radiogenic Ar 81 %
Age estimate 38.45Ma
age of intrusion
Type of analysis conventional K-Ar
REPEAT AR ANALYSIS
Rock or mineral analyzed biotite
Analytical details
Lab sample ID 3
Decay constants 4.72E-04, 0.585E-04, 1.19E-04*
K2O concentration 7.99 %
Radiogenic 40Ar concentration 4.47
Radiogenic Ar 83 %
Age estimate 38.92Ma
age of intrusion
Type of analysis conventional K-Ar
POTASSIUM VALUE IS AVERAGE OF 8 ANALYSES
Rock or mineral analyzed hornblende
Analytical details
Lab sample ID 3
Decay constants 4.72E-04, 0.585E-04, 1.19E-04*
K2O concentration 1.077 %
Radiogenic 40Ar concentration 0.61
Radiogenic Ar 71 %