9706019 Tauxe The PIs will study the variability of the intensity of Earth's magnetic field using sedimentary records. Investigations of the Oligocene sequence of sediments recovered during Leg 73 at Hole 522 in the South Atlantic produced relative paleointensity data of high quality that allow specific predictions to be made about the long term behavior of the geomagnetic field in ancient times. Those data suggest that the average paleofield intensity is related to reversal frequency and that the variability of the data is proportional to the mean intensity. If these observations can be verified elsewhere, they provide profound constraints on the process which generates the field, and in this study, the PIs will continue this work in the Paleogene. They will focus on generating records from latitudinally distributed locations for two time slices in the Oligocene from DSDP/ODP cores and will test whether sedimentary sequences can be found that preserve a record of the field. They will also perform a feasibility study on Italian limestone sequences to investigate possible changes in paleointensity near the Cretaceous Normal Superchron, which is suggested by a statistical study of the Oligocene data from Hole 533. ***
