On the identification of magnetostratigraphic polarity zones |
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| Authors: | Email author" target="_blank">O?ManEmail author |
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| Institution: | (1) Institute of Geology, Acad. Sci. Czech Republic, Rozvojová 135, 165 00 Praha 6, Czech Republic |
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| Abstract: | Polarity zones of sedimentary sections reflect a pattern of alternating polarity of the geomagnetic field recorded by the
remanent magnetization of rocks. Unfortunately, this pattern can have been modified by the variable sedimentation rate, which
complicates the identification of polarity zones against the reference geomagnetic polarity time scale. To avoid this obstacle,
the present paper suggests a transform applied to both the sequence of levels of polarity reversal horizons and the sequence
of ages of polarity reversals before computing their cross-correlation. This transform usually reduces the impact of the variable
sedimentation rate so that a sequence of more than eight polarity reversal horizons may be identified without biostratigraphic
constraints. Numerical experiments involving random processes to simulate both the duration of polarity reversals and the
sedimentation rate proved, however, that not all the parts of a hypothetical stratigraphic section spanning the past 165 Ma
would be equally suitable for dating by magnetic polarity stratigraphy.
A program performing both the compilation of polarity zones from the directions of the primary magnetization sampled along
a section and subsequent identification of these polarity zones is made available online. |
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| Keywords: | paleomagnetism geomagnetic polarity reversals magnetic polarity stratigraphy |
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