National Geochronological Database sample #3294

Outcrop or artificial surface exposure, Granodiorite

Geographic location
-116.698333, 40.308611
116° 41' 54" W, 40° 18' 31" 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 -116.698333, 40.308611
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K-Ar age determinations

Age estimate 38.23Ma
age of intrusion
Type of analysis conventional K-Ar
POTASSIUM VALUE IS AVERAGE OF 3 ANALYSES
Rock or mineral analyzed biotite
Analytical details
Lab sample ID 2
Decay constants 4.72E-04, 0.585E-04, 1.19E-04*
K2O concentration 8.79 %
Radiogenic 40Ar concentration 4.89
Radiogenic Ar 78 %
Age estimate 38.08Ma
age of intrusion
Type of analysis conventional K-Ar
REPEAT AR ANALYSIS
Rock or mineral analyzed biotite
Analytical details
Lab sample ID 2
Decay constants 4.72E-04, 0.585E-04, 1.19E-04*
K2O concentration 8.79 %
Radiogenic 40Ar concentration 4.87
Radiogenic Ar 55 %