Geochimical and isotopic properties of Fram strait sediments , Artic Ocean. A paleoceanographic and paleoclimatic approach

• Main Author: Maccali, Jenny
• Other Authors: Laboratoire Réactions et Génie des Procédés (LRGP), Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), Université de Lorraine, Laurie Reisberg, Claude Hillaire-Marcel, Jean Carignan
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: HAL CCSD 2012
• Subjects: Arctic Ocean; Paleoceanography; Sediments; radiogenic isotopes; Océan Arctique; Paléocéanographie; Isotopes radiogéniques; Paléo-océanographie-Arctique; Océan; Paléoclimatologie-Arctique; Sédiments marins; Géochimie isotopique; [SDU.STU]Sciences of the Universe [physics]/Earth Sciences; Arctic; Chukchi Sea; East Siberian Sea; Pacific; Arctique*; Chukchi; Fram Strait; Ice Sheet; Nordic Seas; North Atlantic; Sea ice
• Online Access: https://hal.univ-lorraine.fr/tel-01750037; https://hal.univ-lorraine.fr/tel-01750037/document; https://hal.univ-lorraine.fr/tel-01750037/file/DDOC_T_2012_0347_MACCALI.pdf

Freshwater exports (sea-ice and oceanic currents) from the Arctic Ocean to the nordic seas is a critical component of the Atlantic Meridional Overturning Circulation and hence of the climatic system. Factors controling those exports are still partially unknown. An indirect way of tracing the intensity and patterns of sea-ice circulation is to trace the origin of the sediments it carries and that settle along the main drift routes towards the North Atlantic. We hence document a direct sedimentary flux that is linked to the detrital particle matrices. Another flux, this one being indirect, comes from the dissolved elements that adsorb onto particles along continental margins where sedimentary fluxes are the highest. We have extracted the authigenic (dissolved) phase from the sediment in order document the evolution of water-masses in Fram Strait since the last glacial maximum. Pb, Nd and Sr isotopic data allowed us to identify two sedimentary sources from the late glacial to the onset of the younger Dryas : canadian and western russian margins, then covered by large ice sheets. After the Younger Dryas however, sedimentary supplies originate from several sources including Greeland, Chukchi Sea and East Siberian Sea margins. The authigenic phase displays a change from 19.8 to 16.4 ka likely linked to the early deglaciation of the Eurasian ice sheet. More recently, [Epsilon]Nd values reflect a more important contribution from the Pacific on water masses exiting through Fram Strait Les flux d'eau douce, glace de mer et courants océaniques, de l'Océan Arctique vers les mers nordiques jouent un rôle critique sur l'Atlantic Meridional Overturning Circulation et donc sur le système climatique. Les facteurs contrôlant ces flux sont encore partiellement méconnus. Un moyen indirect de retracer l'intensité et les schémas de circulation de la glace de mer est de retracer l'origine des sédiments qu'elle transporte, et qui sédimentent le long des grands courants de glace et d'eau douce vers l'Atlantique Nord. Il s'agit donc de ...