Quality of Time Scales — a Statistical Appraisal
A primary concern of geologists is the relative ordering of events in Earth history. On a regional basis, spatial relationships of separate or overlapping rock bodies are used for accomplishing this goal. For correlation over large distances between regions or when the rate of change of geological processes is being considered, it is necessary to use the numerical time scale which is mainly based on radiometric dates of variable. precision. Existing statistical models for estimating the ages of chronostratigraphic boundaries and the corresponding error bars are reviewed. An alternative approach based on the method of maximum likelihood is presented. Computer simulation experiments are described to compare estimates obtained by different methods from small samples of age determinations. A spline-fitting technique can be used to combine estimates for successive stage boundaries with one another. The Jurassic time scale is used to exemplify this statistical approach.
KeywordsWeighting Function Maximum Likelihood Estimator Percent Confidence Interval Smoothing Spline Geologic Time Scale
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