Constraints on the Northwestern Atlantic Deep Water Circulation From 231 Pa/ 230 Th During the Last 30,000 Years

Global climatic changes during the last glacial and deglacial have been related to variations of the Atlantic Meridional Overturning Circulation (AMOC). Here, we present new and refined 231 Pa/ 230 Th down‐core profiles extending back to 30 ka BP from the northwestern Atlantic along the Atlantic Deep Western Boundary Current, which is the main component of the southward deep backflow of the AMOC. Besides the well‐known Bermuda Rise records, available high‐resolution 231 Pa/ 230 Th data in the northwestern Atlantic are still sparse. Our new records along with reconstructions of deep water provenance from Nd isotopes constrain the timing and magnitude of past changes in AMOC from an additional northwestern Atlantic region forming a depth transect between 3,000‐ and 4,760‐m water depth. Our extended and improved data set confirms the weakening of the AMOC during deglacial cold spells such as Heinrich Event 1 and the Younger Dryas interrupted by a reinvigoration during the Bølling‐Allerød interstadial as seen in the prominent 231 Pa/ 230 Th records from the Bermuda Rise. However, in contrast to the Bermuda Rise records, we find a clearly reduced circulation strength during the Last Glacial Maximum in the deep Atlantic. Four new 231 Pa/ 230 Th records form a depth transect in the northwestern Atlantic in millennial‐scale resolution back to 30 ka Combined records resolve millennial‐scale deep water variabilities like YD, B/A, HS1, LGM, and HS2 Timing and magnitude of record variations are in line with the well‐known Bermuda Rise record with exception of the LGM