Paleoventilation Ages in the Deep Pacific

Project Summary Overview Ocean ventilation age estimates for the Last Glacial Maximum (LGM; 19-23 ky BP) present a conundrum. Radiocarbon results from low sedimentation rate sites (<10 cm/kyr) imply deep water ventilation ages were ~800-1000 years older than today, whereas high sedimentation rate sites (>20 cm/kyr) show no substantial difference from today. The contrast is due to either: 1) bioturbation-driven biases in low accumulation rate locations, or 2) the lack of high accumulation rate records from water depths below 3 km. Here we propose to address this problem by acquiring new high-resolution stable isotope and radiocarbon data from high deposition rate sites in the western North Pacific. We propose to obtain sediment cores from the margin of Mindanao in the western Pacific at water depths between 2500 and 3800m. Intellectual Merit Testing whether the ocean sequestered CO 2 would be a major step forward in solving the grand challenge of glacial/interglacial CO 2 cycles. Our research is critical to this effort because previous attempts to evaluate whether ventilation ages were greater during glaciations has been hampered by a lack of high-resolution data sets from the deep (> 3 km) Pacific, which is the largest potential reservoir for the storage of carbon.