Uranium-lead method of age determination. Part II. North American localities

Journal Article · Tue Jan 01 04:00:00 EST 1957 · Geological Society of America, Bulletin

DOI:https://doi.org/10.1130/0016-7606(1957)68[1117:UMOAD]2.0.CO;2· OSTI ID:4793264

Eckelmann, W R; Kulp, J L

Many new isotopic age determinations by the uranium-lead method were made on most of the important North American localities from which primary uranium minerals were reported. With the aid of other published isotopic U-Pb age measurements, it was attempted to interpret the most probable age for each locality and to assign a reasonable uncertainty to that age. The recognition of differential lead loss, the relation of alteration to mineral type, the importance of radon leakage for young samples, and the potential analytical errors make it timely to conduct such a re-evaluation. Among the well established ages are: Spruce Pine district, North Carolina, 360 plus or minus 20 m.y.; Portland, Connecticut, 265 plus or minus 10 m.y.,; Front Range, Colorado, 59 plus or minus 5 m.y.; Black Hills, South Dakota, 1620 plus or minus 20 m.y.; southeast Manitoba, 2650 plus or minus 100 m.y.; Lake Athabasca, Saskatchewan, 1900 plus or minus 50 m.y.; and the Wilber-force area, 1050 plus or minus 20 m.y. Other probable ages are Bedford, New York, 350 m.y.; Colorado Plateau, 60 m.y.; Coeur d'Alene, 1200 m.y.; and Great Bear Lake, Northwest Territories, 1500 m.y. Although there may have been several regional metamorphic events in the Appalachian Province in the Precambrian, the post-Cambrian effects appear at only two periods centering on 260 and 360 m.y. The Grenville metamorphism appears limited to a narrow time interval about 1050 m.y. ago. The Front Range and Colorado Plateau uranium mineralization may have been one event occurring about 60 m.y. ago.

• Research Organization: Originating Research Org. not identified
• Sponsoring Organization: USDOE
• NSA Number: NSA-16-029197
• OSTI ID: 4793264
• Journal Information: Geological Society of America, Bulletin, Journal Name: Geological Society of America, Bulletin Journal Issue: 9 Vol. 68; ISSN 0016-7606
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

07 ISOTOPE AND RADIATION SOURCES
58 GEOSCIENCES
AGE ESTIMATION
CHEMICAL REACTIONS
DECOMPOSITION
DISTRIBUTION
ERRORS
GEOCHEMISTRY
LEAD
LEAD ISOTOPES
LOSSES
QUANTITY RATIO
RADON
URANIUM ISOTOPES
URANIUM MINERALS