National Geochronological Database sample #15445

Outcrop or artificial surface exposure, Quartz monzonite

Geographic location
-110.945, 33.397778
110° 56' 42" W, 33° 23' 52" N
Gila county, AZ
Inspiration 1:24,000 scale map quadrangle
Accurate to within 1 minute (~1 mile)
GLOBE-MIAMI DISTRICT
Source of sample Outcrop or artificial surface exposure
Rock name Quartz monzonite
Description LOST GULCH QUARTZ MONZONITE
Laboratories USGS Menlo Park
Compiler name Marvin, R.F.
Date compiled 1984 11
Precision of location Accurate to within 1 minute (~1 mile)
Location comment GLOBE-MIAMI DISTRICT
Bibliographic reference Creasey, S.C., 1980, Chronology Of Intrusion and Deposition Of Porphyry Copper Ores, Globe-Miami District, Arizona: Economic Geology, v. 75, p. 830-844.
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Geologic map unit -110.945, 33.397778
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K-Ar age determinations

Age estimate 60.9 ± 0.7Ma
Type of analysis conventional K-Ar
Rock or mineral analyzed biotite
Analytical details
Lab sample ID 42
Decay constants 4.962E-04, 0.581E-04, 1.1167E-04
Radiogenic 40Ar concentration 8.4456
Radiogenic Ar 73 %
Comments PRECAMBRIAN AGE HAS BEEN RESET BY LATE CRETACEOUS-PALEOCENE THERMAL EVENTS