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Abstract: Virtues and Vices of the Paleomagnetic Method as Applied to Marine Sedimentary Cores
N. D. Watkins
The geomagnetic polarity has changed irregularly at least twenty times during the last five million years. These polarity changes are world-wide synchronous events and are readily recorded by most sediments of fine silt or smaller size. For reasons which are not clearly understood, polarity and faunal changes sometimes occurred simultaneously. It follows that the paleomagnetic method is a very powerful technique for resolution of Plio-Pleistocene stratigraphic problems, such as exist in the sediments of the Gulf of Mexico.
It will be shown that, like many new techniques, the method is dangerously susceptible to misapplication. This misapplication may result from lack of consideration of: a) variable deposition rates; b) disconformities and unconformities; c) faunal redeposition; d) magnetic recording lag of consolidating sediment; e) an imperfectly defined polarity history; f) limitations of unoriented cores in low latitudes; g) experimental difficulties. Examples of resulting difficulties will be illustrated by presentation of results from continuing studies of deep-sea sedimentary cores from the South Pacific.
It is concluded that the study of paleomagnetism in marine sedimentary cores parallels the earliest conventional stratigraphic methods, in that integration of several disciplines is required for efficient and reliable exploitation of the technique.
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ACKNOWLEDGMENTS AND ASSOCIATED FOOTNOTES
Florida State University, Tallahassee, Florida
Copyright © 1999 by The Gulf Coast Association of Geological Societies