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The fold test in paleomagnetism as a parameter estimation problem
Author(s) -
Watson Geoffrey S.,
Enkin Randolph J.
Publication year - 1993
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/93gl01901
Subject(s) - remanence , fold (higher order function) , confidence interval , paleomagnetism , geology , monte carlo method , statistics , mathematics , geophysics , computer science , physics , magnetization , programming language , quantum mechanics , magnetic field
Most proposed fold test formulations use significance tests to try pre‐tilting and post‐tilting remanence hypotheses. We suggest that it is better to consider the fold test as a parameter estimation problem. Making the usual assumption that the distribution of remanence vectors was originally roughly parallel, we propose, using a monte carlo simulation technique, to estimate the amount of tectonic tilting at the time of magnetization along with a 95% confidence interval. If, for example, this confidence interval included 100% then one could not rule out pre‐tilting remanence. In the older terminology, the fold test is positive. The k‐ratio test of McElhinny [1964] is often said to be conservative in that if a study passes the k‐ratio test then it certainly passes a more rigorous test. We show with a typical counter‐example that this assertion is incorrect. Observational uncertainty of bedding directions is easily included in this formulation.