Paleomagnetic Studies of Transitional Field Behavior with Emphasis on the Comparison of Different Types of Recordings

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Paleomagnetic observations of transitional field behavior come from a wide varkety of igneous and sedimentary structures. Yet it may be that no one rock type possesses the capabilities to render ideaÕ recordings, both in terms of vector field changes as well as temporal accuracy. Indeed, each type of recording appears to have its own set of advantages as well as limitations. The two studies planned promise not only to shed light on the geomagnetic reversal process, but also to enhance our knowledge regarding the relationship between record fidelity and rock type. The first project, presently ongoing, involves the attainment of the polarity transition corresponding to the termination of the Olduvai normal polarity event from lavas on Moloka, Hawaii. The derived record, when complete, will be rigorously compared to a published record of the same transition obtained from nearby deep-sea sediments. The second project involves the attainment of detailed paleofield behavior of sequential reversals recorded in exposed, rapidly-deposited marine sediments along the Mangapoike River on New Zealand's North Island. The sequence has been well-correlated to the late Miocene. Akaroa Volcano, on New Zealand's South Island - the previous focus of transitional field studies by this P.I. - appears to have been created contemporaneously with the marine sediments. This situation provides a rare opportunity to compare transition records derived from two paleomagnetically distinct, yet desirable rock types. As has been the case with past paleomagnetic projects at Cal Poly, several undergraduates will take part throughout the proposed projects, from assistance in the field to laboratory analysis. Some will undertake an aspect of the original research as their own and produce a senior project.