The PI proposes to test the reliability of records of reversals from ODP advanced piston coring (APC) cores. This is an enormous potential reservoir of reversals records, but there have been repeated suggestions that these sediment records are anomalous and cannot be relied upon. The first target will be to test for radial overprints using comparison between off center samples and between archive and working half records of particular reversals. The second stage will be to look for overprints by testing for antipodality in normal and reversed sections close to reversals. Finally, the individual transitional samples will be subjected to AF and thermal demagnetization with principal component analysis. Anisotropy of susceptibility and anhysteretic remanence will be used to check against the confounding effect of magnetic fabric on the directions recorded. To determine relative intensity across the reversals, normalization will be by susceptibility, anhysteretic remanence and saturation isothernal remanence. The result of this work will be a set of documented tests of particular reversal records that can be widely used to assess the fidelity of ODP sediment records. The results will also bear upon the important question of the fidelity of relative intensity records from ODP cores.
