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Geomagnetic field behavior before and after the Kauai reverse‐normal polarity transition

2001; American Geophysical Union; Volume: 106; Issue: B1 Linguagem: Inglês

10.1029/2000jb900319

2156-2202

Scott W. Bogue,

Geophysical and Geoelectrical Methods

New paleomagnetic results from 4 m.y. old lava flows from Kauai, Hawaii, suggest that strong poloidal field is associated with an unusual state of the geodynamo that follows attempts at polarity reversal (successful or not). The new data comprise 50 paleomagnetic sites from superposed lava flows occurring just below and above the Kauai reverse‐normal polarity transition. A composite record of 45 distinct field determinations was constructed by combining sites that record similar ancient field and correlating them to previously published results from Kauai. Of the 45 data, 25 include paleointensity estimates derived from double‐heating experiments. A comparison of the composite record from Kauai with two similar data sets from volcanic sequences shows that field variability (in direction, intensity, or both) can change substantially across a polarity transition. These changes, however, do not appear to be systematic in sign or magnitude. The only feature common to all three records is high field strength in the posttransitional interval, interpreted here as a transient phenomenon associated with the reversal process.