Late Cenozoic sea level changes, their timing and amplitude in offshore New Zealand: Results from IODP Expedition 317

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IODP Expedition 317 dilled a shelf-slope system in the Canterbury Basin on the eastern margin of the South Island of New Zealand. Seven major core discontinuities correspond to Pleistocene sequence boundaries interpreted on the seismic profiles. An Oxygen isotopic curve and a depth-age curve were generated based on isotopic analysis of benthic foraminifera coupled with biostratigraphy. Sea level amplitudes between glacial and interglacial stages were reconstructed by the analysis of fossil ostracode assemblage taking into consideration subsidence and sedimentation rates. The sequence boundaries that follow the mid-Pleistocene transition correspond to the highest-amplitude oxygen isotope positive excursions that occur during this period (MIS 22, 16, 12, 8 and 6) and the corresponding sequence durations are ~0.2 m.y.. We estimate that eustatic amplitudes were ~50 m from 1.8 to 1.26 Ma and exceed 100 m from 0.9 Ma to present.