Disturbance of pre-reversal's Matuyama-Brunhes paleomagnetic sediment record (ODP Leg 175, Hole 1082C)

Abstract

Here we investigate the changes of paleomagnetic data on a deep-sea sediment from the ODP Leg 175, Hole 1082C in the South Atlantic, Walvis Basin. Sedimentary section (40 cm Uchannel sample (2x2 cm) between 81.4-81.8 mcd) was chosen to study the composition and magnetic signature in detail.

The magnetic data showed that the sediment includes oscillations in VGP latitude just before the Matuyama-Brunhes reversal. We investigated this phenomenon in detail, and checked variations of the NRM/SIRM ratio of the sediment.

This ratio is an eciency of the magnetic acquisition and, in general, is sensitive to sedimentation rate and/or lock in depth. The data revealed that prior the onset of VGP oscillation the sediment had low sedimentation rate, while after and during the oscillation onset the sediment had fast sedimentation rate.

We interpret this change in sedimentation rate by disturbance of the sediment due to liquefaction commonly associated with seismicity. Onset of fast sedimentation rate may thus be evidence of tektite formation (indochinites) connected with signicant seismic event.

This is supported by presence of glass particles in this sedimentary section.