Radiocarbon and 230Th data reveal rapid redistribution and temporal changes in sediment focussing at a North Atlantic drift ...

• Main Authors: Mollenhauer, Gesine, McManus, Jerry F., Wagner, Thomas, McCave, I. Nick, Eglinton, Timothy I.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Columbia University 2011
• Subjects: Oceanography; FOS: Earth and related environmental sciences; Geochemistry; Marine sediments; North Atlantic; Northeast Atlantic
• Online Access: https://dx.doi.org/10.7916/d8qj7t13; https://academiccommons.columbia.edu/doi/10.7916/D8QJ7T13

In locations of rapid sediment accumulation receiving substantial amounts of laterally transported material the timescales of transport and accurate quantification of the transported material are at the focus of intense research. Here we present radiocarbon data obtained on co-occurring planktic foraminifera, marine haptophyte biomarkers (alkenones) and total organic carbon (TOC) coupled with excess Thorium-230 (230Thxs) measurements on four sediment cores retrieved in 1649–2879 m water depth from two such high accumulation drift deposits in the Northeast Atlantic, Björn and Gardar Drifts. While 230Thxs inventories imply strong sediment focussing, no age offsets are observed between planktic foraminifera and alkenones, suggesting that redistribution of sediments is rapid and occurs soon after formation of marine organic matter, or that transported material contains negligible amounts of alkenones. An isotopic mass balance calculation based on radiocarbon concentrations of co-occurring sediment components ...