Geomagnetic field intensity from 71 to 12 ka as recorded in deep-sea sediments of the Blake Outer Ridge, North Atlantic Ocean

In this paper we estimate relative geomagnetic field paleointensity between 71 and 12 kyrs BP as recorded in three deep sea sediment cores from the Bl ake Outer Ridge, western North Atlantic Ocean. Paleointensities were estima ted by normalizing sediment natural remanent magnetization separately to (1 ) magnetic susceptibility, (2) anhysteretic remanent magnetization and (3) saturation isothermal remanent magnetization (SIRM). In one core, paleointe nsities were estimated within short time windows which display uniform sedi ment magnetic characteristics, and offsets between windows were removed to minimize environmental biases. We find that most features of our records ar e preserved regardless of normalizer choice, but Lye chose SIRM as the best normalizer fbr the final paleointensity estimates. Our three records prese rve and agree upon a number of short-duration (similar to 10(3) years) pale ointensity features even though the cores are separated by almost 250 km. W e conclude that these are real geomagnetic field signals of at least local extent. We also identify a number of differences between our records which must be artifacts of sediment remanence acquisition or paleointensity norma lization. Such artifacts occur as either (1) baseline shifts between time i ntervals with slightly different sediment magnetic characteristics or (2) d ifferences in amplitude of short duration events. In spite of these environ mental biases, the number and ages of relative paleointensity highs and low s are preserved. Thus sediment paleointensity estimates may be used locally for high-resolution chronostratigraphic correlation. Correlation of our pa leointensity records with other records from the same extended region (Nort h Atlantic Ocean-western Europe) indicates that major paleointensity featur es appear in all regional records. However, differences in the ages and dis agreement in magnitude and number of individual features call into doubt th e use of these relative paleointensity records for high-resolution chronost ratigraphic correlation on a broader regional scale or for quantitative est imation of past geomagnetic field variability.