Résumé
Our understanding of the mechanisms controlling eustatic sea level and global climate changes has been hampered by a lack of appropriate fossil coral records over the last 500 ky, particularly into and out of the glacial periods. This problem was addressed by International Ocean Discovery Program Expedition 389, which drilled a unique succession of Hawaiian drowned coral reefs now at 110-1300 meters below sea level (mbsl). The four objectives are to investigate (1) the timing, rate, and amplitude of sea level variability to examine cryosphere and geophysical processes, including the assessment of abrupt sea level change events; (2) the processes that determine changes in mean and high-frequency (seasonal-interannual) climate variability from times with different boundary conditions (e.g., ice sheet size, pCO (sub 2) , and solar forcing); (3) the response of coral reef systems to abrupt sea level and climate changes; and (4) the variations through space and time of the subsidence and the volcanic evolution of the island. To achieve these objectives, 35 holes at 16 sites in water depths ranging 131.9-1241.8 mbsl were drilled during the expedition. Cores were computed tomography (CT) scanned and then opened and hyperspectral scanned and described. Preliminary assessment of the age and quality of the reef and volcanic cores suggest that many of the expedition objectives will be met.