Browsing by Author "Fersi, Wiem"
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- Consistently dated Atlantic sediment cores over the last 40 thousand yearsPublication . Waelbroeck, Claire; Lougheed, Bryan C.; Vazquez Riveiros, Natalia; Missiaen, Lise; Pedro, Joel; Dokken, Trond; Hajdas, Irka; Wacker, Lukas; Abbott, Peter; Dumoulin, Jean-Pascal; Thil, François; Eynaud, Frédérique; Rossignol, Linda; Fersi, Wiem; Albuquerque, Ana Luiza; Arz, Helge; Austin, William E. N.; Came, Rosemarie; Carlson, Anders E.; Collins, James A.; Dennielou, Bernard; Desprat, Stéphanie; Dickson, Alex; Elliot, Mary; Farmer, Christa; Giraudeau, Jacques; Gottschalk, Julia; Henderiks, Jorijntje; Hughen, Konrad; Jung, Simon; Knutz, Paul; Lebreiro, Susana; Lund, David C.; Lynch-Stieglitz, Jean; Malaizé, Bruno; Marchitto, Thomas; Martínez-Méndez, Gema; Mollenhauer, Gesine; Naughton, Filipa; Nave, Silvia; Nürnberg, Dirk; Oppo, Delia; Peck, Victoria; Peeters, Frank J. C.; Penaud, Aurélie; Portilho-Ramos, Rodrigo da Costa; Repschläger, Janne; Roberts, Jenny; Rühlemann, Carsten; Salgueiro, Emilia; Sanchez Goni, Maria Fernanda; Schönfeld, Joachim; Scussolini, Paolo; Skinner, Luke C.; Skonieczny, Charlotte; Thornalley, David; Toucanne, Samuel; Rooij, David Van; Vidal, Laurence; Voelker, Antje; Wary, Mélanie; Weldeab, Syee; Ziegler, MartinRapid changes in ocean circulation and climate have been observed in marine-sediment and ice cores over the last glacial period and deglaciation, highlighting the non-linear character of the climate system and underlining the possibility of rapid climate shifts in response to anthropogenic greenhouse gas forcing. To date, these rapid changes in climate and ocean circulation are still not fully explained. One obstacle hindering progress in our understanding of the interactions between past ocean circulation and climate changes is the difficulty of accurately dating marine cores. Here, we present a set of 92 marine sediment cores from the Atlantic Ocean for which we have established age-depth models that are consistent with the Greenland GICC05 ice core chronology, and computed the associated dating uncertainties, using a new deposition modeling technique. This is the first set of consistently dated marine sediment cores enabling paleoclimate scientists to evaluate leads/lags between circulation and climate changes over vast regions of the Atlantic Ocean. Moreover, this data set is of direct use in paleoclimate modeling studies.
- Environmental changes in the Fleuve Manche paleoriver drainage system (Western Europe) linked to North Atlantic sub-millennial climate variability across Heinrich Stadial 1: Palynological evidence from the Bay of BiscayPublication . Penaud, Aurélie; Fersi, Wiem; Toucanne, Samuel; Goñi, Maria Fernanda Sánchez; Rossignol, Linda; Naughton, Filipa; Wary, Mélanie; Eynaud, FrédériqueMarine microfossils (dinoflagellate cysts and planktonic foraminifera) and geochemical (XRF-Ti/Ca)-based matic records from a core (MD13-3438) located off the Fleuve Manche (FM) paleo-mouth have revealed sustained warm summer sea surface temperatures (SSTs) during sub-millennial climate changes within (similar to 18-14.7 ka) may have played a key role in the FM regime related to the European Ice Sheet (EIS) melting In this study, we have analyzed the MD13-3438 pollen content over the HS1 at a mean resolution of similar to 50 years test whether vegetation-based air temperatures were coupled to SSTs face to this rapid climate variability. our results highlight two major phases of pollen sources at site MD13-3438, preventing the pollen record interpreted as a continuous record of the evolution of vegetation and climate occupying a single watershed HS1. The first phase, i.e. the HS1-a interval (similar to 18-16.8 ka), is marked by strong occurrences of boreal pollen (especially Picea-Abies). Considering their spatial distribution and the coalescence of the British and Scandinavian ice sheets into the North Sea during the Last Glacial Maximum, these taxa probably originated from North European Plain, i.e., eastern FM tributaries (east of the Rhine River), where cool-humid conditions generally prevailed. Then, the second phase, i.e. the HS1-b interval (similar to 16.8-14.7 ka BP), is characterized deceleration of the EIS retreat and the drop of boreal pollen values at site MD13-3438 further signing influence of the upstream FM drainage system and thus a better characterization of pollen sources related western FM tributaries. Superimposed to these two HS1 main phases, pollen fluctuations are concomitant sub-millennial variability in the EIS deglaciation intensity. During the early HS1 (HS1-a), we discuss two short-term increases in the ratio between deciduous trees (Quercus-Corylus-Alnus) and herbaceous plants (Plantago-Amaranthaceae-Artemisia). These events are coeval with phases of increasing dinocyst-based SST seasonality through summer SST amplification). We associate these events with lower contribution of the upstream catchment as well as, possibly, atmospheric warming and regional sea-level positive oscillations. The HS1-b composed of three main phases that appear more influenced by the downstream FM drainage system. HS1-b1 (16.8-16.3 ka BP) corresponds to the driest and coldest conditions west of the Rhine River. HS1-b2 (16.3-15.5 ka BP) is coeval with large arrivals of iceberg from the Hudson strait in the Bay of Biscay and likely to a major sea-level positive oscillation associated with a phase of FM valley reworking. HS1-b3 (15.5-14.7 ka BP) corresponds to persistent arid conditions that preceded the subsequent more humid tions recorded from 14.7 ka BP at the start of the Bolling-Allerod.