Terrestrial cooling and changes in hydroclimate in the continental interior of the United States across the Eocene-Oligocene boundary

• Published in: GSA Bulletin
• Main Authors: Fan, Majie, Ayyash, Sara A., Tripati, Aradhna, Passey, Benjamin H., Griffith, Elizabeth M.
• Other Authors: Department of Earth and Environmental Sciences Arlington, University of Texas at Arlington Arlington, Department of Earth, Planetary and Space Sciences Los Angeles (EPSS), University of California Los Angeles (UCLA), University of California (UC)-University of California (UC), Department of Atmospheric and Oceanic Sciences Los Angeles (AOS), Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Johns Hopkins University (JHU), Ohio State University Columbus (OSU), ANR-10-LABX-0019,LabexMER,LabexMER Marine Excellence Research: a changing ocean(2010)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2018
• Subjects: ACL; spatial-distribution; antarctic glaciation; atmospheric co2; central rocky-mountains; climate transition; clumped-isotope geochemistry; great-plains; groundwater temperature response; north-american midcontinent; northwestern nebraska; [SDE.BE]Environmental Sciences/Biodiversity and Ecology; [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; Antarctic; Antarc*
• Online Access: https://hal.science/hal-02626092; https://doi.org/10.1130/B31732.1

WOS:000437009200002 International audience One of the most pronounced climate transitions in Earth's history occurred at the Eocene-Oligocene transition, similar to 34.0-33.6 m.y. ago. Marine sedimentary records indicate a dramatic decline in pCO(2) coeval with global cooling during the transition. However, terrestrial records are relatively sparse, with conflicting interpretations of hydroclimate in continental interiors. Here, we provide quantitative constraints on the response of the continental hydroclimate in the western United States across the Eocene-Oligocene boundary by studying clumped isotope temperatures [T(Delta(47))], delta C-13 and delta O-18 values of vadose carbonates, and delta C-13 values of bulk organic matter (delta C-13(org)) in eastern Wyoming. Our results show that T(Delta(47)) dropped from similar to 28 degrees C to similar to 21 degrees C, indicating similar to 7 degrees C cooling in air temperature, which occurred parallel to the decrease in atmospheric pCO(2) during the latest Eocene-early Oligocene. We find that aridity and the biome were stable, and ice-volume-corrected precipitation PO decreased similar to 1.6 parts per thousand across the Eocene-Oligocene boundary, attributable to reduced vapor condensation temperatures. These new quantitative data add to the growing body of evidence suggesting a marked terrestrial response in temperature and hydroclimate across the Eocene-Oligocene transition. Our findings indicate a pattern of greenhouse-gas- induced global temperature change in the continental interior of the United States that was roughly 1.5-2x the magnitude of cooling in the global ocean.