Browsing by Author "Rossignol, Linda"
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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.
- ForCenS-LGM: a dataset of planktonic foraminifera species assemblage composition for the last glacial maximumPublication . Jonkers, Lukas; Mix, Alan; Voelker, Antje; Risebrobakken, Bjørg; Smart, Christopher W.; Ivanova, Elena; Arellano-Torres, Elsa; Eynaud, Frédérique; Naoufel, Haddam; Max, Lars; Rossignol, Linda; Simon, Margit H.; Martins, Maria Virgínia Alves; Petró, Sandro; Caley, Thibaut; Dokken, Trond; Howard, Will; Kucera, MichalSpecies assemblage composition of marine microfossils offers the possibility to investigate ecological and climatological change on time scales inaccessible using conventional observations. Planktonic foraminifera - calcareous zooplankton - have an excellent fossil record and are used extensively in palaeoecology and palaeoceanography. During the Last Glacial Maximum (LGM; 19,000 - 23,000 years ago), the climate was in a radically different state. This period is therefore a key target to investigate climate and biodiversity under different conditions than today. Studying LGM climate and ecosystems indeed has a long history, yet the most recent global synthesis of planktonic foraminifera assemblage composition is now nearly two decades old. Here we present the ForCenS-LGM dataset with 2,365 species assemblage samples collected using standardised methods and with harmonised taxonomy. The data originate from marine sediments from 664 sites and present a more than 50% increase in coverage compared to previous work. The taxonomy is compatible with the most recent global core top dataset, enabling direct investigation of temporal changes in foraminifera biogeography and facilitating seawater temperature reconstructions.
- Modern relationships between microscopic charcoal in marine sediments and fire regimes on adjacent landmasses to refine the interpretation of marine paleofire records: an Iberian case studyPublication . Genet, Marion; Daniau, Anne-Laure; Mouillot, Florent; Hanquiez, Vincent; Schmidt, Sabine; David, Valérie; Georget, Muriel; Abrantes, Fatima; Anschutz, Pierre; Bassinot, Franck; Bonnin, Jérome; Dennielou, Bernard; Eynaud, Frédérique; Hodell, David A.; Mulder, Thierry; Naughton, Filipa; Rossignol, Linda; Tzedakis, Polychronis; Sánchez-Goñi, Maria FernandaMarine microcharcoal records provide invaluable information to understand changes in biomass burning and its drivers over multiple glacial and interglacial cycles and to evaluate fire models under warmer climates than today. However, quantitative reconstructions of burnt area, fire intensity and frequency from these records need calibration studies of the current fire-microcharcoal relationship. Here, we present the analysis of microcharcoal concentration and morphology in 102 core-top sediment samples collected in the Iberian margin and the Gulf of Cadiz. We show that microcharcoal concentrations are influenced by the water depth or the distance from the river mouth. At regional scale, the mean microcharcoal concentrations and microcharcoal elongation (length to width ratio) show a marked latitudinal variation in their distribution, primarily controlled by the type of burnt vegetation in the adjacent continent. High microcharcoal concentrations in marine sediments represent rare, large and intense fires in open Mediterranean woodlands. Based on these results, the increasing trend of microcharcoal concentrations recorded since 8 ka in the well-known marine sedimentary core MD95-2042 off the Iberian margin indicates the occurrence of large and infrequent fires of high intensity due to the progressive degradation of the Mediterranean forest and the expansion of shrublands.