The paleomagnetic stratigraphy of the Southern Ocean: 20° West to 160° East longitude

Abstract

Correlations between 159 cores from the Southern Ocean has been established using paleomagnetic polarity changes. Isopach charts of the sediments using the Brunhes/Matuyama boundary (0·7 million years) and the Matuyama/Gauss boundary (2·35 million years) reveal regional changes in sedimentation rates that can be related to changes in Antarctic glaciation. This influenced paleocurrent structure and sedimentary conditions. Brunhes age sediments range from 0 to more than 16 meters in thickness, and reveal scour zones or areas of low deposition beneath the circumpolar current and where currents flow along the bottom from the Wedeell and Ross seas. Matuyama sediments are generally thinner and do not show the effects of the circumpolar current in the area of investigation. The position of the belt of siliceous oozes and probably the 0°C surface-water isotherm has migrated sporadically south more than 5° of latitude from Gauss to Brunhes time in response to waning glaciation. Antarctic glaciation was initiated more than 5·0 million years ago, but insufficient data are presently available to delineate earlier history.