National Geochronological Database sample #12941

Outcrop or artificial surface exposure, Monzonite

Geographic location
-117.578333, 36.273333
117° 34' 42" W, 36° 16' 24" N
Inyo county, CA
Darwin 1:62,500 scale map quadrangle
Accurate to within 1 minute (~1 mile)
ROAD 1 KM EAST OF DARWIN
Source of sample Outcrop or artificial surface exposure
Rock name Monzonite
Description MONZONITE OF DARWIN STOCK
Laboratories University of California, Santa Barbara
Compiler name Singh, P.
Date compiled 1983 06
Precision of location Accurate to within 1 minute (~1 mile)
Location comment ROAD 1 KM EAST OF DARWIN
Bibliographic reference Chen, J.H., and Moore, J.G., 1982, Uranium-lead isotopic ages from the Sierra Nevada Batholith, California: Journal of Geophysical Research, v. 87, No. B6, p. 4761-4784.
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Geologic map unit -117.578333, 36.273333
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U-Th-Pb age determinations

Age estimates
174.9Ma by 206Pb/238U
175.1Ma by 207Pb/235U
178Ma by 207Pb/206Pb
Rock or mineral analyzed zircon
+200 MESH FRACTION
Analytical details
Lab sample ID 77
Decay constants 1.55125E-04, 9.8485E-04, 4.9475E-05
204Pb concentration 0.131
206Pb concentration 75.61
207Pb concentration 5.67
208Pb concentration 18.59
Comments on analysis 238U=468 PPM, 206PB=11.14 PPM
Comments STOCK IS AROUND 175 M.Y. OLD