# Global Correlations of Organic Matter Carbon Isotopes at Eccentricity Timescales throughout the Valanginian Stage

Elyès Ben Saïd, Mathieu Martinez, Anne-Catherine Pierson-Wickmann, Pierre Pellenard, Et Al.

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Elyès Ben Saïd, Mathieu Martinez, Anne-Catherine Pierson-Wickmann, Pierre Pellenard, Et Al. Global Correlations of Organic Matter Carbon Isotopes at Eccentricity Timescales throughout the Valanginian Stage. 29 ème édition de la réunion des sciences de la Terre (RST 2025), Société Géologique de France (SGF), Oct 2025, Montpellier, France. pp.666492. insu-05353035

HAL Id: insu-05353035

https://insu.hal.science/insu-05353035v1

Submitted on 7 Nov 2025

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# Global Correlations of Organic Matter Carbon Isotopes at Eccentricity Timescales throughout the Valanginian Stage

Elyès Ben Said*, Mathieu Martinez†1, Anne-Catherine Pierson-Wickmann‡, Pierre Pellenard<fnref n="2" />, Minka Moreau-Ledegen<fnref n="3" />, Ana Le Douarec, Jade Sevigne, Blanche Tran, and François Baudin<fnref n="4" />

## Résumé

High-resolution paleoclimatic reconstructions require precise temporal correlations, a goal that remains unachieved at orbital timescales in the Mesozoic. In this study, we aim to establish orbitally-paced correlations across 3 geographically distant basins spanning the Valanginian Stage (Early Cretaceous). This interval is characterized by large-amplitude organic carbon isotope excursions concomitant with a neritic carbonate production crisis. A total of 350 samples were analyzed for organic-carbon δ13C from 3 sites: DSDP Site 534 (western Atlantic Ocean), Vergol-Morénas in the Vocontian Basin (GSSP of the Valanginian Stage; SE France), and Cerro La Parva (western Argentina). The values of δ13Corg values range from -30.1‰ to -23.8‰ in DSDP Site 534, -29.7‰ to -27.1‰ in the Vergol-Morénas section and -24.4‰ to -21.5‰ in Cerro La Parva. The trends in the δ13Corg show common features in between the different sites and several negative peaks within the Weissert Event, identified in the Somanakamura group in Japan (Tomura et al., 2025), are also observed in the Vocontian and Neuquén basins (Moreau-Ledegen et al., 2025). The correlation of the different sites using these common features show a pacing of the δ13Corg by the 405-ka eccentricity cycle. This highlights the potential of δ13Corg as a reliable proxy for recording orbital forcing and demonstrates it as a robust tool for chemostratigraphic correlation at a global scale in order to align paleoclimatic signals at an unprecedented time resolution for the Early Cretaceous.

**Mots-Clés:** organic carbon isotopy, valanginian, correlation, vocontian basin, neuquén basin, dsdp

<footnote n="1">¹Géosciences Rennes, OSUR – Université de Rennes I, CNRS : UMR6118 Géosciences Rennes, Observatoire des Sciences de l'Univers de Rennes – France</footnote>

<footnote n="2">²Biogéosciences UMR 6282, CNRS, Université Bourgogne Europe, 6 Boulevard Gabriel, 21000 Dijon – UMR 6282 Biogéosciences – France</footnote>

<footnote n="3">³Biogéosciences UMR 6282, CNRS, Université Bourgogne Europe, 6 Boulevard Gabriel, 21000 Dijon – CNRS, Université Bourgogne Europe – France</footnote>

<footnote n="4">⁴Institut des Sciences de la Terre de Paris – Institut National des Sciences de l'Univers, Sorbonne Université, Centre National de la Recherche Scientifique, CY Cergy Paris Université – France</footnote>

<footnote>*Intervenant</footnote>

<footnote>†Auteur correspondant: mathieu.martinez@univ-rennes1.fr</footnote>

<footnote>‡Auteur correspondant: anne-catherine.pierson-wickmann@univ-rennes.fr</footnote>