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Calculation of 230ThU isochrons, ages, and errors

January 1, 1994

If analytical errors are responsible for the scatter of points on a 230Th-234U-238U isochron diagram, the isochron should be fitted by a technique that1. weights the points according to their analytical errors and error correlations, and

  • 2. either takes into account the presence of some of the same data in two coupled XY isochrons or (equivalently) uses a single, three-dimensional XYZ isochron.

A method based on maximum-likelihood estimation is presented that fulfills these requirements, and the relevant equations for errors in age and initial 234U238U">234U238U are given. Equations for estimating the necessary isotope-ratio errors and error-correlations for both alpha-spectrometric and mass-spectrometric data are also developed.

Publication Year 1994
Title Calculation of 230ThU isochrons, ages, and errors
DOI 10.1016/0016-7037(94)90229-1
Authors K. R. Ludwig, D.M. Titterington
Publication Type Article
Publication Subtype Journal Article
Series Title Geochimica et Cosmochimica Acta
Index ID 70017618
Record Source USGS Publications Warehouse
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