SED Solid Earth Discussions SED Solid Earth Discuss. 1869-9537 Göttingen, Germany 10.5194/se-2021-12 Tectonics, Climate and Topography: Oxygen stable isotopes and the early Eocene growth of the Pyrenees Honegger Louis 1 Adatte Thierry https://orcid.org/0000-0002-4319-2212 2 Spangenberg Jorge E. https://orcid.org/0000-0001-8636-6414 3 Poyatos-Moré Miquel https://orcid.org/0000-0001-7813-8868 4 Ortiz Alexandre 5 6 Curry Magdalena 7 Huyghe Damien 8 Puigdefàbregas Cai 9 Garcés Miguel https://orcid.org/0000-0001-7666-6392 10 Vinyoles Andreu 10 Valero Luis https://orcid.org/0000-0003-1356-721X 1 Läuchli Charlotte 11 Nowak Andrés 1 Fildani Andrea 12 Clark Julian D. 13 Castelltort Sébastien https://orcid.org/0000-0002-6405-4038 1 Department of Earth Sciences, University of Geneva, Rue des Maraîchers 13, 1205 Geneva, Switzerland Institut of Earth Sciences, Géopolis, University of Lausanne, 1015 Lausanne, Switzerland Institute of Earth Surface Dynamics (IDYST), Géopolis, University of Lausanne, 1015 Lausanne, Switzerland Department of Geosciences, University of Oslo, Sem Sælands vei 1, 0371 Oslo, Norway Université de Pau et des Pays de l’Adour, LFCR, UMR5150, 64000 Pau, France TOTAL, CSTJF, 64018, Pau Cedex, France Department of Earth and Atmospheric Sciences3507 Cullen Blvd.University of Houston INES ParisTech, PSL University, Centre de Géosciences, 35 rue St Honoré, 77305, Fontainebleau, Cedex, France Department of Earth and Ocean Dynamics, University of Barcelona, C/ Martí i Franquès, s/n, 08028 Barcelona, Spain Department of Earth and Ocean Dynamics & Geomodels Research Institute, Faculty of Earth Sciences, Universitat de Barcelona, Spain Freie Universität Berlin, Division of Tectonics and Sedimentary Geology, Malteserstr. 74-100, 12249 Berlin, Germany The Deep Time Institute, P.O. Box 27552, Austin, Texas 78755-7552, USA Equinor Research Center, 6300 Bridge Point Parkway, Building 2, Suite 100, Austin, Texas, USA 04 03 2021 2021 1 35 Copyright: © 2021 Louis Honegger et al. 2021 This work is licensed under the Creative Commons Attribution 4.0 International License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/4.0/ This article is available from https://se.copernicus.org/preprints/se-2021-12/ The full text article is available as a PDF file from https://se.copernicus.org/preprints/se-2021-12/se-2021-12.pdf

<p>The topographic history of an orogen, a key element to study the interactions of the climate and tectonic conditions that drove it, can be reconstructed by inverting the sedimentary record of its adjacent basins. Previous tectono-stratigraphic studies, including flexural models, and sparse stable oxygen and carbon isotope data from the South-Pyrenean foreland basin suggest a major topographic rise occurred in the late Paleocene-early Eocene. To further test this hypothesis, we present a stack of 658 stable isotope measurements on whole-rock marine carbonate mudstone from a 4800-m-thick composite sedimentary succession which provides a 12&thinsp;Ma continuous record of environmental conditions during the early to middle Eocene (54 to 42&thinsp;Ma). From the base of this record (at 54&thinsp;Ma), oxygen isotopes (δ<sup>18</sup>O values) show a faster decrease rate than the coeval global negative excursion associated with the Early Eocene Climatic Optimum (EECO). This local alteration of the global δ<sup>18</sup>O signal indicates that topographic growth during this period, associated with significant tectonic activity, perturbed the oxygen isotopic composition of foreland waters. Thus, our data suggest that significant topographic uplift of the Pyrenean orogen started from at least 54&thinsp;Ma and continued until ca. 49&thinsp;Ma, reaching the maximum elevations of 2000&thinsp;±&thinsp;500&thinsp;m in this phase from previous isotope and flexural studies. In addition, our record shows that the long-term carbon stable isotope composition during this period remained relatively stable with no similarity to the global bell-shaped long-term trend of the EECO. This is consistent with the restricted physiography of the South-Pyrenean foreland basin, mainly influenced by local sedimentary and water inputs. Overall, the Pyrenean topographic growth from the late Cretaceous to the Miocene displays several growth stages that seem to be primarily determined by episodes of increased rate of tectonic plate convergence. The duration of these growth stages (several millions of years) is a possible documentation of the response time of mountain ranges to tectonic perturbations. The results of this work, therefore, demonstrate that stable isotope measurements on whole-rock sediments in foreland basins can provide key information for tectono-climatic and topographic reconstructions of mountain ranges.</p>