Asynchronous Responses in Benthic d18O across Glacial Terminations

Benthic d¹⁸O is often used as a stratigraphic tool to place marine records on a common age model and as a proxy for the timing of ice volume/sea level change. However, Skinner and Shackleton [2005] found that the timing of benthic d¹⁸O change at the last termination differed by 4000 years between two sites in the Atlantic and Pacific. These results suggest that benthic d¹⁸O change may not always accurately record the timing of terminations, and that age models developed by aligning benthic d¹⁸O may have significant errors. We compare benthic d¹⁸O records from 20 Atlantic sites and 14 Pacific sites to evaluate differences in the timing of terminations as recorded by benthic d¹⁸O. Statistical analysis of sedimentation rates derived from the alignment of benthic d¹⁸O suggests an Atlantic lead over Pacific benthic d¹⁸O change during the last 6 terminations. We estimate an average termination age difference of 1100 years between the Atlantic and Pacific, approximately consistent with the delay expected due to ocean mixing rates, given that most glacial meltwater probably enters the North Atlantic. However, we also find evidence of brief 4000 yr lags during the middle of several terminations, suggesting that termination mid-points may make poor d¹⁸O tie points.