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doi:10.2204/iodp.proc.320321.201.2012

Summary

We revised the shipboard composite sections of Sites U1331, U1332, U1333, and U1334 from Expedition 320 and Sites 1218, 1219, and 1220 from Leg 199 using shipboard magnetic susceptibility data, GRA bulk density data, natural remanent magnetization data, and core images. Drilling distortions in cores are compensated by differential squeezing and stretching of parallel cores outside the splice at all investigated sites. This is of major importance because we want to integrate all available data from all drilled holes. A detailed site-to-site correlation was performed. We linked the revised composite sections of Sites U1333, U1334, and 1219 to the corrected rmcd of Site 1218. Sites U1331 and U1332 were correlated to the revised composite record of Site 1220. We chose Sites 1218 and 1220 as reference sites because of their stratigraphic completeness. The decimeter-scale correlation was used to integrate and transfer paleomagnetic and biostratigraphic information. Our integrated stratigraphic framework presented here can be used as the backbone for the late Eocene, Oligocene, and early Miocene intervals of the equatorial Pacific Cenozoic megasplice. Because of the presence of clear paleomagnetic records and decimeter-scale cyclic features, the investigated sediments are exceptionally suitable for further working on cyclostratigraphy and orbital tuning. The integration of Expedition 320 and Leg 199 data has the potential to substantially improve the existing geological timescale (Gradstein et al., 2004) and even extend the astronomically calibrated timescale (Lourens et al., 2004; Pälike et al., 2006) far back into the Eocene.

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