National Geochronological Database sample #3439

Outcrop or artificial surface exposure, Rhyolite porphyry

Geographic location
-116.683333, 40.3
116° 41' " W, 40° 18' " N
Lander county, NV
Crescent Valley 1:62,500 scale map quadrangle
Accurate to within 1 minute (~1 mile)
NORTHERN SHOSHONE RANGE; NW1/4 SEC. 16, T28N, R47E; AT ALTENBERG HILL
Source of sample Outcrop or artificial surface exposure
Rock name Rhyolite porphyry
Description RHYOLITE PORPHYRY DIKE
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 NORTHERN SHOSHONE RANGE; NW1/4 SEC. 16, T28N, R47E; AT ALTENBERG HILL
Bibliographic reference Silberman, M.L., and Mckee, E.H., 1971, K-Ar Ages Of Granitic Plutons In North-Central Nevada: Isochron/West, No. 1, p. 15-32.
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Geologic map unit -116.683333, 40.3
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K-Ar age determinations

Age estimate 35.68 ± 0.7Ma
age of intrusion
Type of analysis conventional K-Ar
REPLICATE ARGON ANALYSES
Rock or mineral analyzed biotite
Analytical details
Lab sample ID 8. USGS(M)-M125
Decay constants 4.72E-04, 0.585E-04, 1.19E-04*
K2O concentration 8.24 %
Radiogenic 40Ar concentration 4.275
Radiogenic Ar 8084 %
Age estimate 35.59 ± 0.7Ma
age of intrusion
Type of analysis conventional K-Ar
Rock or mineral analyzed sanidine
Analytical details
Lab sample ID 8. USGS(M)-M125
Decay constants 4.72E-04, 0.585E-04, 1.19E-04*
K2O concentration 11.6 %
Radiogenic 40Ar concentration 6.003
Radiogenic Ar 98 %