A LATE PLEISTOCENE-HOLOCENE NOBLE GAS PALEOTEMPERATURE RECORD IN SOUTHERN MICHIGAN
In addition to the general warming trend observed between the LGM and present time, the noble gas temperature (NGT) record indicates an abrupt warming event between ~12.8 and 11.1kyrs BP, correlative to the Bolling-Allerod (BOA) warm phases. Such abrupt warming is followed by a climate reversal, possibly the Younger Dryas. Ice-sheet-linked changes in freshwater delivery to the North Atlantic, as well as changes in the North Atlantic Deep Water (NADW) circulation are possibly at the origin of such abrupt climate shifts in northeastern US.
Our NGT record reveals a ~3 °C temperature difference within the last millennium. Unfortunately, lack of age resolution through 14C does not allow for a detailed paleoclimatic reconstruction within this period.
Analysis of δ18O and δD reveal, for most samples, a lack of correlation with NGTs and thus, with local precipitation temperatures. Importantly, Pleistocene waters with the coldest recharge temperatures present the most positive δ18O and δD values, suggesting a dominant latitude effect over local precipitation temperatures, and thus, an atmospheric circulation pattern distinct from present time during the early deglaciation periods, with a stronger moisture component from the Gulf of Mexico.