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| Bachem, Paul E.; Risebrobakken, Bjorg; De Schepper, Stijn; Mcclymont, Erin L.. |
| The Pliocene was a time of global warmth with small sporadic glaciations, which transitioned towards the larger-scale Pleistocene glacial-interglacial variability. Here, we present high-resolution records of sea surface temperature (SST) and ice-rafted debris (IRD) in the Norwegian Sea from 5.32 to 3.14 Ma, providing evidence that the Pliocene surface conditions of the Norwegian Sea underwent a series of transitions in response to orbital forcing and gateway changes. Average SSTs are 2 degrees C above the regional Holocene mean, with notable variability on millennial to orbital timescales. Both gradual changes and threshold effects are proposed for the progression of regional climate towards the Late Pliocene intensification of Northern Hemisphere... |
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| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00495/60710/65332.pdf |
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| Van Nieuwenhove, Nicolas; Head, Martin J.; Limoges, Audrey; Pospelova, Vera; Mertens, Kenneth; Matthiessen, Jens; De Schepper, Stijn; De Vernal, Anne; Eynaud, Frédérique; Londeix, Laurent; Marret, Fabienne; Penaud, Aurélie; Radi, Taoufik; Rochon, André. |
| Organic-walled resting cysts of planktonic dinoflagellates occur commonly in modern marine sediment where they represent, with rare exceptions, the only geologically preservable part of the life cycle. Although many species do not produce fossilizable resting cysts, upper Quaternary sediments contain a diverse cyst record that is used frequently for paleoenvironmental reconstruction and stratigraphic analysis. Reconstructions of past sea-surface conditions rely on an understanding of the distributions of dinoflagellate cysts in modern sediments linked to their respective environmental parameters, underpinned by sound taxonomy and standardized nomenclature. Stratigraphic studies additionally require knowledge of morphological details to distinguish extant... |
| Tipo: Text |
Palavras-chave: Dinoflagellate cysts; Marine; Quaternary; Gymnodiniales; Gonyaulacales; Peridiniales. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00606/71817/70324.pdf |
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| Mertens, Kenneth; Van Nieuwenhove, Nicolas; Gurdebeke, Pieter R.; Aydin, Hilal; Bogus, Kara; Bringue, Manuel; Dale, Barrie; De Schepper, Stijn; De Vernal, Anne; Ellegaard, Marianne; Grothe, Arjen; Gu, Haifeng; Head, Martin J.; Heikkila, Maija; Limoges, Audrey; Londeix, Laurent; Louwye, Stephen; Marret, Fabienne; Masure, Edwige; Matsuoka, Kazumi; Mudie, Peta J.; Penaud, Aurelie; Pospelova, Vera; Price, Andrea Michelle; Ribeiro, Sofia; Rochon, Andre; Sangiorgi, Francesca; Schreck, Michael; Torres, Vladimir; Uzar, Serdar; Versteegh, Gerard J. M.; Warny, Sophie; Zonneveld, Karin. |
| We present a summary of two round-table discussions held during two subsequent workshops in Montreal (Canada) on 16 April 2014 and Ostend (Belgium) on 8 July 2015. Five species of the genus Achomosphaera Evitt 1963 and 33 of the genus Spiniferites Mantell 1850 emend. Sarjeant 1970 occuring in Pliocene to modern sediments are listed and briefly described along with remarks made by workshop participants. In addition, several holotypes and topotypes are reillustrated. Three species previously assigned to Spiniferites are here considered/accepted as belonging to other genera: Impagidinium inaequalis (Wall and Dale in Wall et al. 1973) Londeix et al. 2009, Spiniferites? rubinus (Rossignol 1962 ex Rossignol 1964) Sarjeant 1970, and Thalassiphora balcanica... |
| Tipo: Text |
Palavras-chave: Spiniferites; Achomosphaera; Hafniasphaera; Rottnestia; Pterocysta. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00471/58304/60844.pdf |
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| Panitz, Sina; De Schepper, Stijn; Salzmann, Ulrich; Bachem, Paul E.; Risebrobakken, Bjorg; Clotten, Caroline; Hocking, Emma P.. |
| During the mid-Piacenzian, Nordic Seas sea surface temperatures (SSTs) were higher than today. While SSTs provide crucial climatic information, on their own they do not allow a reconstruction of potential underlying changes in water masses and currents. A new dinoflagellate cyst record for Ocean Drilling Program (ODP) Site 642 is presented to evaluate changes in northward heat transport via the Norwegian Atlantic Current (NwAC) between 3.320 and 3.137Ma. The record is compared with vegetation and SST reconstructions from Site 642 and SSTs from Iceland Sea ODP Site 907 to identify links between SSTs, ocean currents, and vegetation changes. The dinocyst record shows that strong Atlantic water influence via the NwAC corresponds to higher-than-present SSTs and... |
| Tipo: Text |
Palavras-chave: Dinoflagellate cysts; Norwegian Atlantic Current; Arctic Front; Northward heat transport; Obliquity forcing; Late Pliocene. |
| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00504/61595/65879.pdf |
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| Risebrobakken, Bjorg; Andersson, Carin; De Schepper, Stijn; Mcclymont, Erin L.. |
| The Pliocene (5.3-2.6Ma) is often described as a relatively stable climatic period, with warm temperatures characterizing high latitudes. New suborbital resolved stable isotope records from Ocean Drilling Program Hole 642B in the eastern Nordic Seas document that the Pliocene was not a stable period characterized by one climate. Rather, seven distinct climate phases, each lasting between 150,000 and 400,000years, are identified and characterized in the time interval 5.1-3.1Ma. Four of the transitions between the defined climate phases occurred close to an eccentricity minimum and a minimum in amplitude of change for Northern Hemisphere summer insolation, while two occurred around an eccentricity maximum and a maximum in amplitude in insolation change.... |
| Tipo: Text |
Palavras-chave: Pliocene; Nordic Seas; Stable isotopes; Diagenetic calcite; Paleogeography; External and internal forcing. |
| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00504/61599/65864.pdf |
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