HR: 12:00h
AN: GP52B-03 INVITED    [Abstracts]
TI: Evaluation of paleointensity experimental data: detection of non-ideal recording mechanisms
AU: * Tauxe, L
EM: ltauxe@ucsd.edu
AF: AU: ben Yosef, E
EM: ebenyose@ucsd.edu
AF: Dept. Anthropology, UCSD, La Jolla, CA 92093, United States
AU: Ron, H
EM: hagairon@vms.huji.ac.il
AF: Hebrew Univ Jerusalem, Inst of Earth Sci Edmond Safra Campus, Jerusalem, 91904, Israel
AB: Paleointensity information derived from thermal remanences have a long history dating back to the 1930s. Because many experiments yield data of uncertain quality, much effort has been put in to assessing data reliability. There are more than dozens of reliability indicators based on experimental results. But the decision on threshold values for the variety of paleointensity statistics has been extremely subjective and there seems to be no "magic bullet" set of cutoff values that guarantee the reliability of a given result. We have developed a new approach to setting cutoff values in which we have tried to minimize the subjectivity of the process. We argue that the single most convincing attribute of any scientific study is reproducibility and simply find the set of cutoff values that yield the maximum number of samples with the most specimens with consistent results. Therefore, instead of setting numerous cutoff values arbitrarily, we set a single statistic, the cooling unit standard deviation cutoff, expressed as the percent of the mean. The set of statistics that yields the most consistent results at a cooling unit level for a given standard deviation cutoff is then used for selection of specimens. We find that in most studies, the most effective parameter in reducing within site scatter is the one that is most sensitive to specimen alteration. Also, somewhat counter to intuition, stricter cutoff values frequently improve consistency of results. Finally, alternating between in-field/zero field cooling and zero-field/in-field cooling steps (the so-called IZZI method) yields the most information about domain state and specimen alteration of any of the popular experimental protocols.
DE: 1521 Paleointensity
DE: 1540 Rock and mineral magnetism
DE: 1594 Instruments and techniques
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2007 Fall Meeting