Laurentide Ice Sheet extent over the last 130 thousand years traced by the Pb isotope signature of weathering inputs to the Labrador Sea

• Published in: Quaternary Science Reviews
• Main Authors: Parker, RL, Foster, GL, Gutjahr, M, Wilson, PA, Littler, KL, Cooper, MJ, Michalik, A, Milton, JA, Crocket, KC, Bailey, I
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier 2022
• Subjects: Quaternary; Paleoceanography; North Atlantic; Last Glacial Cycle; Labrador Current; Continental runoff; Chemical weathering; Rare earth elements; Fe–Mn oxyhydroxides; Ice Sheet; Labrador Sea
• Online Access: http://hdl.handle.net/10871/130239; https://doi.org/10.1016/j.quascirev.2022.107564

This is the final version. Available from Elsevier via the DOI in this record. Data availability: The new IODP Site U1302/3 data presented and compiled Superior Province Pb isotope data are available in the attached Excel spreadsheets. Supplement 1 and 2 is also deposited in PANGAEA. Understanding the history of continental ice-sheet growth on North America, and in particular that of the Laurentide Ice Sheet (LIS), is important for palaeoclimate and sea-level reconstructions. Information on ice-sheet extent pre-dating the Last Glacial Maximum (LGM) is heavily reliant, though, on the outputs of numerical models underpinned by scant geological data. Important aspects of LIS history that remain unresolved include the timing of its collapse during Termination 2, the first time that it expanded significantly during the Last Glacial Cycle, and whether its volume was significantly reduced during marine isotope stage (MIS) 3. To address these issues and more, we present authigenic iron-manganese (Fe–Mn) oxyhydroxide-derived high-resolution records of Pb isotope data and associated rare earth element profiles for samples spanning the past ∼130 kyr from northwest North Atlantic Labrador Sea, IODP Site U1302/3. We use these new data to track chemical weathering intensity and solute flux to the Labrador Sea associated with LIS extent on the adjacent highly radiogenic (high Pb isotope composition) North American Superior Province (SP) craton since the Penultimate Glacial Maximum (PGM). Our new records show that relatively high (radiogenic) values characterise warm marine isotope stages (MIS) 5, 3 and 1 and the lowest (most unradiogenic) values occurred during cold stages MIS 6, 4 and 2. The radiogenic Pb isotope excursion associated with Termination 2 is short-lived relative to the one documented for Termination 1, suggesting that LIS retreat during the PGM was relatively fast compared to the LGM and that its collapse during the last interglacial occurred ∼125 ka. Highly radiogenic inputs to the Labrador Sea during MIS ...