Sediment delivery and depositional patterns off Adélie Land (East Antarctica) in relation to late Quaternary climatic cycles

• Published in: Marine Geology
• Main Authors: Presti, Massimo, Barbara, Loïc, Denis, Delphine, Schmidt, Sabine, de Santis, Laura, Crosta, Xavier
• Other Authors: Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales Toulouse (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales Toulouse (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Université Paris 1 Panthéon-Sorbonne (UP1), Environnements et Paléoenvironnements OCéaniques (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École Pratique des Hautes Études (EPHE), Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2011
• Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography; [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology; Antarc*; Antarctic; Antarctica; East Antarctica; EPICA; ice core; Sea ice
• Online Access: https://hal.science/hal-02105651; https://doi.org/10.1016/j.margeo.2011.03.012

International audience This study focuses on the understanding of depositional patterns over late Quaternary glacial/interglacial cycles and of the influence of diagenesis on geochemical sedimentary records from the continental margin off Adélie Land (East Antarctica). We provide a complete analysis of the 30-m-long sediment core MD03-2603, collected on a deep-sea sediment mound deposit. The LR04 benthic oxygen isotope stack vs. down-core records of Ba/Al and Ba/Ti atomic ratios, reflectance data and micropaleontological evidence, allow to determine a detailed chronology back to ~ 490 ka BP. Long-lived Uranium and Thorium (238 U, 234 U, 232 Th, and 230 Th) provide an assessment of lateral vs. vertical sediment advection, by constraining the sediment focusing factor (Φ). Φ is high in most glacial intervals, when mostly detrital material was transported down-slope and focused to the core area. Interglacials display highs in Ba/Al and Ba/Ti, coupled to low Φ values, related to stronger contour current flow. Biogenic fractions are more abundant during interglacials and more diluted by detrital fractions during glacials. The diatom assemblage is dominated by the open-ocean species Fragilariopsis kerguelensis, but glacial intervals display an increase of sea-ice related and coastal species. The integrated approach (high-resolution record of major and minor elements, U auth , δ 15 N, N org , δ 13 C, and C org) provides key insights into how redox conditions affect glacial/interglacial sedimentation processes. Our evidence shows that diagenetic effects, due to development of reducing conditions and consequent higher preservation of organic matter, may overprint the paleoclimatic significance of some proxies involved into a sequence of diagenetic remineralization pathways. Comparison of the marine record to ice-core data (EPICA Dome C-EDC) allows to extend the information to the whole East Antarctic margin. Sediment proxies of increased burial of biogenic material, or increased preservation of organic matter, are ...