Early Cenozoic climate and tectonic evolution of the southwest Pacific Ocean

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The Paleocene-Eocene world was dominated by warm conditions and the absence of permanent polar ice. A late Paleocene-early Eocene climate warming plummeted with the early Eocene climatic optimum (EECO; ~52-50 Ma), which was followed by a cooling trend over the middle-late Eocene that eventually drove the Earth to the present-day polar glacial condition. The early Paleogene long-term climate history was also punctuated by several transient (~10^3-10^5 yr) hyperthermal events. While the Northern Hemisphere is well represented by many outcropping and deep-sea magnetic-polarity calibrated records, the Southern Hemisphere is still lacking of an adequate number of continuous and well-calibrated stratigraphic records, especially the south Pacific, which had a fundamental role in the early Cenozoic heating transport. Given the high quality paleomagnetic results recently obtained by the late Paleocene-middle Eocene marine records cropping out in the South Island of New Zealand, here we propose a paleomagnetic and rock-magnetic study of the Pukemuri and Awheaiti Streams sections cropping out in Tora (Southeast Wairarapa, North Island, New Zealand) and of the Pain de Sucre, Sommet Khian, and Thonon sections cropping out in the Koumac-Gomen area (Grande-Terre Island, New Caledonia). These records will be integrated by magnetostratigraphic analyses of the DSDP Sites 206-210 (Leg 21, southwest Pacific Ocean). The sequence of magnetic polarity reversals from the target sections will be used for correlation with the international geomagnetic polarity time scale, determining a robust age-model of sedimentation. A well-established chronology for the Koumac-Gomen section will constrain the age of the accretionary complex of sediments indicating the onset of the convergence cycle leading to the obduction of New Caledonia. Calcareous nannofossil, foraminifera, radiolarian biostratigraphy and carbon stable isotope stratigraphy will be performed by a team of collaborating research groups. The results will give a complete and chronologically calibrated framework of the biological, physical (magnetic) properties, and carbon cycle evolution of the southwest Pacific. Such a dataset would be a fundamental step forward to understand the climate dynamics of the early Paleogene and it will also serve as basis to improve the models about the future climate changes of the Earth.