Evolution of neodymium isotopic signature of seawater during the Late Cretaceous: implications for intermediate and deep circulation.

• Published in: Gondwana Research
• Main Authors: Moiroud, Mathieu, Pucéat, Emmanuelle, Donnadieu, Yannick, Bayon, Germain, Guiraud, Michel, Voigt, Silke, Deconinck, Jean-François, Monna, Fabrice
• Other Authors: Biogéosciences UMR 6282 (BGS), Université de Bourgogne (UB)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences du Climat et de l'Environnement Gif-sur-Yvette (LSCE), 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-Saclay-Centre National de la Recherche Scientifique (CNRS), Modélisation du climat (CLIM), 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-Saclay-Centre National de la Recherche Scientifique (CNRS)-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-Saclay-Centre National de la Recherche Scientifique (CNRS), Géosciences Marines (GM), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Institute of Geosciences Frankfurt am Main, Goethe-Universität Frankfurt am Main, Archéologie, Terre, Histoire, Sociétés Dijon (ARTeHiS), Ministère de la Culture et de la Communication (MCC)-Université de Bourgogne (UB)-Centre National de la Recherche Scientifique (CNRS), Work supported by funding from the INSU programme SYSTER., ANR-12-BS06-0011,Anox-Sea,Rôle de la configuration des continents dans le développement d'anoxies globales dans l'océan profond.(2012)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2016
• Subjects: Cretaceous; Neodymium isotopes; Ocean circulation; Southern Ocean; [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry; [SDU.STU.ST]Sciences of the Universe [physics]/Earth Sciences/Stratigraphy; Bellinghausen Abyssal Plain; Georgia Basin; Indian; Kerguelen; Maud Rise
• Online Access: https://hal.archives-ouvertes.fr/hal-01356761; https://hal.archives-ouvertes.fr/hal-01356761/document; https://hal.archives-ouvertes.fr/hal-01356761/file/37502_1.pdf; https://doi.org/10.1016/j.gr.2015.08.005

20 pages International audience Neodymium isotopic compositions (εNd) have been largely used for the last fifty years as a tracer of past ocean circulation, and more intensively during the last decade to investigate ocean circulation during the Cretaceous period. Despite a growing set of data, circulation patterns still remain unclear during this period. In particular, the identification of the deep-water masses and their spatial extension within the different oceanic basins are poorly constrained. In this study we present new deep-water εNd data inferred from the Nd isotope composition of fish remains and Fe–Mn oxyhydroxide coatings on foraminifera tests, along with new εNd data of residual (partly detrital) fraction recovered from DSDP Sites 152 (Nicaraguan Rise), 258 (Naturaliste Plateau), 323 (Bellinghausen Abyssal Plain), and ODP Sites 690 (Maud Rise) and 700 (East Georgia Basin, South Atlantic). The presence of abundant authigenic minerals in the sediments at Sites 152 and 690 detected by XRD analyses may explain both middle rare earth element enrichments in the spectra of the residual fraction and the evolution of residual fraction εNd that mirror that of the bottom waters at the two sites. The results point towards a close correspondence between the bottom water εNd values of Sites 258 and 700 from the late Turonian to the Santonian. Since the deep-water Nd isotope values at these two sites are also similar to those at other proto-Indian sites, we propose the existence of a common intermediate to deep-water mass as early as the mid-Cretaceous. The water mass would have extended from the central part of the South Atlantic to the eastern part of proto-Indian ocean sites, beyond the Kerguelen Plateau. Furthermore, data from south and north of the Rio Grande Rise–Walvis Ridge complex (Sites 700 and 530) are indistinguishable from the Turonian to Campanian, suggesting a common water mass since the Turonian at least. This view is supported by a reconstruction of the Rio Grande Rise–Walvis Ridge complex ...