National Geochronological Database sample #14937

Outcrop or artificial surface exposure, Gneiss

Geographic location
-81.972222, 36.138889
81° 58' 20" W, 36° 8' 20" N
Avery county, NC
Elk Park 1:24,000 scale map quadrangle
Accurate to within 1 minute (~1 mile)
NORTH CAROLINA COORDINATES: 882900N, 1122300E; CRANBERRY MINE AREA
Source of sample Outcrop or artificial surface exposure
Rock name Gneiss
Description USUALLY HIGHLY-DEFORMED, COARSE-GRAINED GNEISS (FELDSPAR, QUARTZ, BIOTITE, SPHENE) WITH LAYERS OF FINER-GRAINED, MORE MAFIC MATERIAL; CRANBERRY GNEISS
Laboratories University of North Carolina
Compiler name Marvin, R.F.
Date compiled 1984 08
Precision of location Accurate to within 1 minute (~1 mile)
Location comment NORTH CAROLINA COORDINATES: 882900N, 1122300E; CRANBERRY MINE AREA
Bibliographic reference Fullager, P.D., and Bartholomew, M.J., 1983, Rubidium-Strontium Ages Of The Watauga River, Cranberry, and Crossing Knob Gneisses, Northwestern North Carolina ""In"" Lewis, S.E., ed., Geological Investigations In The Blue Ridge Of Northwestern North Carolina: 1983 Guidebook For The Carolina Geological Society, North Carolina Division Of Land Resources, Article 2, 29p
In Lewis, S.E., Ed., Geological Investigations In The Blue Ridge Of Northwestern North Carolina: 1983 Guidebook For The Carolina Geological Society, North Carolina Division Of Land Resources, Article 2, 29p.
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Geologic map unit -81.972222, 36.138889
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Rb-Sr age determinations

Age estimate 1018 ± 19Ma
Type of analysis 87Sr/86Sr-87Rb/86Sr isochron (whole rock)
22-POINT WHOLE-ROCK ISOCHRON
Rock or mineral analyzed whole rock
Analytical details
Lab sample ID 1967
Sample suite # 615
Decay constants 1.42E-05
Rubidium concentration 91.89 ppm
Strontium concentration 137.2 ppm
Initial 87Sr/86Sr 0.708
Ratio 87Rb/86Sr 1.942
Ratio 87Sr/86Sr 0.73082
Normal? T