Magnetostratigraphy in the eastern Arctic Ocean, further palaeomagnetic results from Ymer-80 cores

Abstract

The reconstruction of palaeoceanographic events in the Canadian Arctic Ocean for the last 4.5 Ma is based on palaeomagnetic reversal stratigraphy of deep sea cores (Herman & Hopkins 1980). The interpretation of palaeomagnetic results in terms of genuine geomagnetic reversals results in sedimentation rates of the order of mm/ka, which is one order of magnitude less than corresponding accumulation rates for the eastern Arctic Ocean. The latter rate is founded on the interpretation of palaeomagnetic results from three cores north of Spitshergen, which carry two zones with negative remanent inclinations confined within oxygen isotope stages 2-3 (Ldvlie et al. 1986). The chronostratigraphic framework is based on CI4, amino acid and oxygen isotope stratigraphies, and the reversals are easily correlated with short duration excursions occurring around 30 and 60 ka, respectively. Since neither polarity chrons nor excursions appear to have unique directional signatures, reversed palaeomagnetic directions cannot be assigned to polarity chrons/subchrons without independent chronostratigraphic control.