Climate and sea level variations in the Gulf of Lion : coupling stable and radiogenic isotopes proxies

• Main Author: Pasquier, Virgil
• Other Authors: Laboratoire Géosciences Océan (LGO), Université de Bretagne Sud (UBS)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Université de Bretagne occidentale - Brest, Marina Rabineau
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: HAL CCSD 2017
• Subjects: Gulf of Lion; North Mediterranean borderland; Glacial-Interglacial; Sedimentary flux; Organic matter stable isotopes; Sedimentation rate; Pyrite sulfur isotopes; Global vs local environmental changes; Golf du Lion; Bordure Nord Méditerranéenne; Variabilité glaciaire-interglaciaire; Flux sédimentaire; Isotopes stables de la matière organique; Taux de sédimentation; Isotopes du soufre des pyrites; Changement environnementaux globaux vs locaux; [SDU.STU]Sciences of the Universe [physics]/Earth Sciences; North Atlantic
• Online Access: https://theses.hal.science/tel-01738260; https://theses.hal.science/tel-01738260v2/document; https://theses.hal.science/tel-01738260v2/file/These-2017-SML-Geosciences_marines-PASQUIER_Virgil.pdf

By its position, the Gulf of Lion is an ideal location for investigation of past ecological changes and processes affecting the sedimentary deposition. Previous work has highlighted the impacts of climatic and glacio-eustatic changes on the GoL stratigraphic organization, but also on terrestrial exports of organic matter.This isotopic study based on the organic carbon and nitrogen preserved in PRGL1-4 sediments highlights important rivers runoff during warm periods of the last 200 000 years.Regional intercomparison with terrestrial and marine records indicates that these river exports resulting from an increase of precipitation over the North Mediterranean borderland.Using PRGL1-4 location, out of Mediterranean cyclogenetic area, we suggest that these pluvial events occurred in response to enhance passage of North Atlantic atmospheric perturbation into the Western Mediterranean basin.Pyrite sulfur isotopes investigations over the last 500 kyr have also been done. The stratigraphic variations (up to 76‰) in the isotopic data reported here are among the largest ever observed in pyrite, and are in phase with glacial-interglacial sea level. These results suggest that there exist important but previously overlooked depositional controls on sedimentary sulfur isotope records. Two different mechanisms influencing the isotopic fractionation can explain the observed dataset: a climatic modulation of the bacterial activity, and / or (ii) a local sedimentary modulation involve during early diagenetic formation of pyrite in relation with the eustatic variations. De par sa position, le Golfe du Lion est un site idéal pour l’investigation des changements paléo-environnementaux et des processus affectant le dépôt sédimentaire. Les travaux antérieurs ont permis de mettre en évidence les impacts de la variabilité climatique et glacioeustatique sur l’organisation stratigraphique de la marge, mais également sur les exports terrestres de matière organique.L’étude isotopique du carbone organique et de l’azote de la matière ...