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https://www.bilketa.eus/ark:/27020/hal-00936049Institut des Sciences de la Terre de Paris (iSTeP) ; Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)Department of Earth and Planetary Sciences [Evanston] ; Northwestern University [Evanston]Department of Geosciences and Natural Resource Management [Copenhagen] (IGN) ; Faculty of Science [Copenhagen] ; University of Copenhagen = Københavns Universitet (UCPH)-University of Copenhagen = Københavns Universitet (UCPH)Centre de recherche sur la Paléobiodiversité et les Paléoenvironnements (CR2P) ; Muséum national d'Histoire naturelle (MNHN)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)Milieu Géologique ; ANDRA DSHusson, DorothéeThibault, NicoilasGalbrun, BrunoGardin, SilviaMinoletti, FabriceSageman, BradHuret, EmiliaHAL, hal-009360492014International audienceCyclostratigraphic analysis of the Maastrichtian limestone-marl alternations of Bidart (SW France) allows the hypothesis of orbital control on lithological cycles to be evaluated. Magnetic Susceptibility (MS), oxygen and carbon isotope measurements, sampled at a high resolution, are analyzed using various cyclostratigraphic tools. A statistically significant orbital signal is detected, with a remarkable record of the precession corresponding to the limestone-marl couplets. This well expressed orbital forcing allows the building of a relative cyclostratigraphic time scale for the MS and δ¹³C records based on the 100 kyr eccentricity cycle. The total duration of the section is estimated at 1.44 ± 0.22 Myr. Correlation based on calcareous nannofossil biostratigraphy and comparison of the scaled Bidart δ¹³C record to the astronomically calibrated δ¹³C signal of ODP hole 762C shows that the studied section extends from -71.5 to -70 Ma, covering the upper part of Chron C32n.1n and 2/3 of Chron C31r. Oxygen isotope data suggest a 2°C cooling of sea-surface temperatures during the studied interval. When placed on the long-term δ¹⁸O trend of the Bidart section, this interval is here recognized as the onset of the early Maastrichtian cooling event. With its excellent record of the precessional forcing, the Bidart section, along with other sections of the Basque country, is a useful tool for the refinement of the Maastrichtian timescale.https://hal.science/hal-00936049https://hal.science/hal-00936049v1/file/Husson_et_al_PALEO3_2014_version_1.pdfArticle de journal | Aldizkari bateko artikuluavignette : https://www.bilketa.eus/in/rest/Thumb/image?id=ark:/27020/hal-00936049&mat=articleNumengArchive ouverte HAL | HAL artxibo irekia[SDU.STU]Sciences of the Universe [physics]/Earth SciencesLower Maastrichtian cyclostratigraphy of the Bidart section (Basque Country, SW France): A remarkable record of precessional forcing