North Atlantic deep-water formation is the starting step of the Meridional Overturning Circulation (MOC), which redistributes heat from low to high latitudes. Therefore, this region is a key modulator of Earth climate. Changes in this system by external forcings will easily propagate by the MOC, ultimately impacting global climate. Hence, the North Atlantic sedimentary record is an ideal archive of past climate changes. Paleoclimate reconstructions rely critically in accurate determinations of the sedimentary fluxes and the timescales of the mechanisms that trigger and propagate climate changes, yet important timescales such as the transport time of the sediments are still difficult to determine. U-series isotopes disequilibria provide an effective tool for reconstructing these fluxes and constraining these timescales. The time-dependence of 234U depletion relative to 238U in silt sized sediments provides a measure of the comminution age; the time elapsed since their production and final deposition. This can be used as a proxy for climate-induced changes in provenance and deep-current circulation. This proposal aims to reconstruct a high-resolution record of the comminution age, sediment fluxes and focusing, and post-depositional history of the last glacial cycle of ODP site 984 (Bjorn Drift, S Iceland). This interdisciplinary approach will involve U-series isotopes, magnetic properties, composition and sedimentological characteristics of these sediments. This project will test the hypothesis of an alternating source of sediments from Europe to Iceland in phase with glacial and interglacial periods, respectively, rather than a change in bottom currents activity. At the same time, it will provide further grounds for analyzing the response of this proxy in time-scales ranging from abrupt climate forcings to millennial-scale cyclicity during the last glacial cycle, which will help understand the role of the North Atlantic in the Quaternary climatic variability.
Field of science
- /humanities/history and archaeology/history
- /social sciences/social and economic geography/transport
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Call for proposal
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