National Geochronological Database sample #3432

Outcrop or artificial surface exposure, Granodiorite

Geographic location
-117.283333, 41.195833
117° 17' " W, 41° 11' 45" N
Humboldt county, NV
Osgood Mountains 1:62,500 scale map quadrangle
Accurate to within 1 minute (~1 mile)
OSGOOD MOUNTAINS; SOUTH-CENTRAL PART OF SEC. 6, T38N, R42E; 1,000 FT. NE OF ALPINE MINE, AT SADDLE
Source of sample Outcrop or artificial surface exposure
Rock name Granodiorite
Description NORTH LOBE OF OSGOOD MOUNTAINS STOCK. MEDIUM-GRAINED BIOTITE-HORNBLENDE 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 OSGOOD MOUNTAINS; SOUTH-CENTRAL PART OF SEC. 6, T38N, R42E; 1,000 FT. NE OF ALPINE MINE, AT SADDLE
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 -117.283333, 41.195833
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K-Ar age determinations

Age estimate 92.1 ± 1.8Ma
age of intrusion
Type of analysis conventional K-Ar
Rock or mineral analyzed biotite
1% CHLORITE
Analytical details
Lab sample ID 1. USGS(M)-MB33B
Decay constants 4.72E-04, 0.585E-04, 1.19E-04*
K2O concentration 8.88 %
Radiogenic 40Ar concentration 12.08
Radiogenic Ar 89 %