The PI has recovered detailed paleomagnetic secular variation records and associated rock magnetic data from high accumulation- rate deep-sea sediments of the Blake Outer Ridge and Bermuda Rise. He has used these results to develop a relative paleointensity record. Results correlate well with three other recent relative paleointensity estimates for the last 100,000 years. However, relative paleointensity record is strongly influenced by environmental effects (magnetic-fraction grain-size variations). The PI will develop new relative paleointensity normalization methods that will better remove subtle environmental effects in our records, and test these methods by sediment redeposition experiments which vary field intensity and magnetic-fraction grain size in both artificial and natural sediments. Results of this study will have broad application to relative paleointensity studies of both deep-sea and lacustrine sediments.
