A Southern Hemisphere record of the Matuyama‐Brunhes polarity reversal

Abstract

We present a record of the Matuyama‐Brunhes (0.73 Ma) polarity transition from a southern hemisphere deepsea sediment core (V16‐58; 46°S, 30°E). The transition is recorded across at least 30 cm of section and is defined by a nearly 180° change in directions which occurs during a low in the relative intensities. An increase in the 10Be/9Be ratios associated with the intensity low suggests that the relative intensities may document a decrease in the strength of the geomagnetic field. The virtual geomagnetic pole (VGP) path is neither clearly near‐ or far‐sided, but tracks approximately 120° west of the site longitude. Considered with other Matuyama‐Brunhes transition records, this southern hemisphere record supports previous interpretations that the Matuyama‐Brunhes transitional field was not dipolar. Instead, the V16‐58 transition together with other records of this reversal recently obtained from this longitudinal sector suggests that nonzonal terms which are symmetric about the equator were important during this transitional field.