TIMING OF BENTHIC &DELTA;<SUP>18</SUP>O CHANGE IN REGIONAL RADIOCARBON DATED STACKS

Local to regional scale non-glacioeustatic effects and the slow mixing time of the deep ocean fundamentally limit the precision of any global benthic δ¹⁸O chronology. The accuracy of an orbitally-tuned Pleistocene d¹⁸O chronology (such as that developed in Lisiecki and Raymo, 2005) depends on how well the temporal relationships between insolation, ice volume / sea level, and benthic δ¹⁸O changes can be constrained and how much is known about sedimentation rate history. We present regional benthic δ¹⁸O stacks covering the Atlantic, Pacific, and Indian Oceans with radiocarbon age models to address the relative influence of glacioeustatic (ice volume / sea level) and non-glacioeustatic (temperature, salinity, ocean circulation) effects on the timing of observed benthic δ¹⁸O changes. The stacks include a total of ~300 individual benthic δ¹⁸O records and the age models are constrained by >800 radiocarbon dates from planktonic foraminifera. The large number of records being used allows us to offer first order constraints on regional reservoir age variability using our benthic δ¹⁸O alignments and initial age models with a constant 400 yr reservoir age. We add to the body of evidence for increased reservoir ages (up to ~1,800 yr) in the high latitude North Atlantic during the early deglaciation and suggest a constant reservoir age at all sites in the South Atlantic to ~44°S. The stacks show a clear decoupling between the rate of change of sea level and benthic δ¹⁸O during the large drop in sea level around the Marine Isotope Stage (MIS) 2/3 boundary, the Last Glacial Maximum, and the last deglaciation (Termination I). We observe that millennial-scale changes in temperature, salinity, and deep ocean circulation affect both the timing and magnitude of changes in the regional benthic δ¹⁸O stacks.