Ventilation History of the Intermediate Western North Atlantic During the Last Deglaciation

Abstract:

Robinson et al. (1) compiled radiocarbon ventilation ages from the western North Atlantic during the last deglaciation (from the LGM to the early Holocene). In that compilation and later studies, there are no data from the early part of the deglaciation at intermediate depths (~1300-2300m). The reasons for that include downslope sediment transport during the LGM for some regions and no deep-sea coral appearance before the late Heinrich Stadial 1 (HS1). For the compiled intermediate-depth data from the rest of the deglaciation, they are from different places, and therefore the spatial variability is mixed with the temporal variability. In this study, we will present a time series of ventilation age using a gravity core-long piston core pair from the New England Slope, based on which we can have a better idea of the temporal evolution of the ventilation strength. Our core is located in the middle of the intermediate depths (1820m) and has high sedimentation rates throughout the deglaciation. Usually apparent ventilation age (benthic ¹⁴C age minus planktic ¹⁴C age) is presented for foraminifera-based ventilation reconstructions. However, there can be a large error for that when the surface reservoir age in the water formation region is much larger than at the core location (e.g., during the early HS1 and the Younger Dryas) because in that case the water left the production region with an old initial age. In this study, we will present adjusted ventilation ages after considering the surface reservoir age history in the subpolar North Atlantic.

1. L. F. Robinson, J. F. Adkins, L. D. Keigwin, et al. 2005. Radiocarbon variability in the western North Atlantic during the last deglaciation. Science 310, 1469-1473.