A Southern-Hemisphere Record of the Matuyama-Brunhes Polarity Reversal

We present a record of the Matuyama-Brunhes (0.73 Ma) polarity transition from a southern hemisphere deep-sea sediment core (V16-58; 46-degrees-S, 30-degrees-E). The transition is recorded across at least 30 cm of section and is defined by a nearly 180-degrees change in directions which occurs during a low in the relative intensities. An increase in the Be-10/Be-9 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-degrees 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.