HR: 10:20h
AN: GP52A-01 INVITED    [Abstracts]
TI: A re-examination of directional and paleointensity results from the Kiaman Reversed Polarity Superchron at Kiama: A single crystal approach
AU: Tarduno, J A
EM: john@earth.rochester.edu
AF: University of Rochester, Department of Earth & Environmental Sciences, 227 Hutchison Hall, Rochester, NY 14627, United States
AU: * Cottrell, R D
EM: rory@earth.rochester.edu
AF: University of Rochester, Department of Earth & Environmental Sciences, 227 Hutchison Hall, Rochester, NY 14627, United States
AB: Long-term paleointensity trends are largely based on comparisons of values from the Cretaceous Normal Polarity Superchron and the preceding and succeeding mixed polarity intervals. Numerous data sets including single plagioclase crystals, submarine basaltic glass and the natural remanent magnetization of submarine basalt suggest an inverse relationship between reversal frequency and field strength over the last approximately 180 million years. Here we extend this examination further into the geologic record by examining the Kiaman Reversed Polarity Superchron. Irving and Parry (1963) recognized that a long period of reversed magnetic polarity existed during the Permian-Late Carboniferous time, named after study of the lavas at Kiama, Australia. A new examination of detailed stepwise demagnetization data from whole rock samples demonstrates complex magnetizations in some of the flows. This complexity probably reflects subsequent geologic events, and the propensity to record such secondary signals in non-ideal magnetic carriers present in whole rock samples. Alternatively, single plagioclase crystals may yield data that can see through the later geologic history as they can contain minute magnetic inclusions. Preliminary paleointensity studies of unoriented plagioclase crystals from the Bombo flow and Dapto latite demonstrate that the single crystal approach is a viable technique to see beyond laboratory and geologic alteration. Results using several variations of the technique will be presented.
DE: 1521 Paleointensity
DE: 1535 Reversals: process, timescale, magnetostratigraphy
DE: 1594 Instruments and techniques
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2007 Fall Meeting