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U-238-U-234-Th-230-Th-232 systematics and the precise measurement of time over the past 500,000 yearsA method is presented for the high-precision measurement of the Th-230 abundance in corals by isotope-dilution mass spectrometry using techniques developed by Chen and Wasserburg (1980, 1981) and Chen et al. (1986). It is shown that 6 x 10 to the 8th atoms of Th-230 can be measured to + or - 30 percent (2 sigma) and 2 x 10 to the 10th atoms of Th-230 to + or - 2 percent. The time over which useful age data on corals can be obtained ranges from a few years to about 500 ky, with the uncertainty in age ranging from 5 y for a 180-y-old coral, to 44 y for a 8294-y-old coral, to 1.1 ky for a 123.1-ky-old coral. Ages were determined with high analytical precision for several corals that grew during high sea-level stands about 120 ky ago, supporting the view that the dominant cause of Pleistocene climate change was Milankovitch forcing.
Document ID
19870045898
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Edwards, R. Lawrence
(California Inst. of Tech. Pasadena, CA, United States)
Chen, J. H.
(California Inst. of Tech. Pasadena, CA, United States)
Wasserburg, G. J.
(California Institute of Technology Pasadena, CA, United States)
Date Acquired
August 13, 2013
Publication Date
January 1, 1987
Publication Information
Publication: Earth and Planetary Science Letters
Volume: 81
Issue: 2-3
ISSN: 0012-821X
Subject Category
Geophysics
Accession Number
87A33172
Funding Number(s)
CONTRACT_GRANT: NAG9-43
Distribution Limits
Public
Copyright
Other

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