(Table T1) Fossil, magnetic reversal, and additional datums of ODP Leg 189 sites@en

The aim of this study is to assess the viability of age models based on shipboard and postcruise bio- and magnetostratigraphic datums, as of August 2002, using independently derived control points. The control points are based on matching between-site trends in stable isotope records, carbonate content, and weight percent sand. Site 1170 on the western South Tasman Rise has a good record of magnetic reversals, which suggests a hiatus prior to ~30 Ma (early Oligocene) relating to the Marshall Paraconformity, followed by strongly reduced sedimentation in the late Oligocene. Preservation of the Mi-1 event at this site is evidence for continued sedimentation across the Oligocene/Miocene boundary. Correlation of the Mi-1a event to the record at Site 1090 on the Agulhas Ridge confirms the usefulness of the magnetostratigraphic record at this site. However, the timing of the Mi-1 event at Site 1170 appears different from that at Site 1090, but is constrained by four magnetic reversals. At Site 1171 additional control points are consistent with biostratigraphic datums. Site 1172 is marked by the lowest sedimentation rates of all sites. Additional control points before 22 Ma are more consistent with the biostratigraphy than with the magnetostratigraphy. At Site 1168 we suggest that the magnetic reversal record MR1 provides the best match with the biostratigraphy and additional control points, as well as changes in the biogenic and lithogenic composition of the sedimentary record. […]