cover image: Phosphate δ13Corg chemostratigraphy from the Gantour basin, Morocco: A proof of concept from the K–Pg transition to mid-Thanetian

20.500.12592/1qvfib7

Phosphate δ13Corg chemostratigraphy from the Gantour basin, Morocco: A proof of concept from the K–Pg transition to mid-Thanetian

1 Jan 2024

The Late Cretaceous–early Paleogene interval is globally associated with transient to long-term changes in the stable carbon isotopic composition of marine carbonates (δ13Ccarb). Based on biostratigraphic reconstruction, this critical period of Earth's history is thought to coincide with the deposition of world heritage Paleocene phosphate deposits (phosphorites) in northwestern Morocco. However, the detailed stratigraphy of the Gantour basin, one of the most important Moroccan phosphate deposits, has not yet been constrained. For instance, the former “Montian” Stage has been used to tentatively approximate the Danian, whereas the succeeding Selandian Stage remains to be identified. Here, we develop a detailed organic carbon isotopic (δ13Corg) curve from phosphorus-rich horizons of the western Gantour sedimentary sequence in an attempt to constrain their stratigraphic placement and depositional age model. Upsection, these strata host long-term negative and positive δ13Corg trends that tend to correlate with global δ13Ccarb records of the Cretaceous–Paleogene and mid-Thanetian transitional boundaries. The data support the presence of Danian and Selandian rocks in the Gantour basin, which are succeeded by strata containing characteristic signatures of the well-known Cenozoic δ13C maximum at 58–57.5 Ma (the Paleocene Carbon Isotope Maximum). Our results shift the previously proposed Cretaceous–Paleogene transition in the Gantour basin further down into the older sediment C2M layer without interfering with recorded massive biological turnover in faunal diversity and abundance. Moreover, the refined stratigraphy suggests that the deposition of the Gantour phosphorites spanned ~8.5 Myr. Our results confirm the utility of δ13Corg chemostratigraphy for dating and correlating phosphate-bearing deposits of the Tethyan province. They have important implications for deciphering Paleocene phosphogenesis, the co-evolution of associated vertebrate groups, and for prospecting phosphorus-rich mineral deposits.

Authors

Jérémie Aubineau, Fleurice Parat, Anne-Catherine Pierson-Wickmann, Michel Séranne, Ernest Chi Fru, Radouan El Bamiki, Abdellatif Elghali, Otmane Raji, Manuel Muñoz, Clément Bonnet, Es-Said Jourani, Oussama Khadiri Yazami, Jean-Louis Bodinier

Bibliographic Reference
Jérémie Aubineau, Fleurice Parat, Anne-Catherine Pierson-Wickmann, Michel Séranne, Ernest Chi Fru, et al.. Phosphate δ13Corg chemostratigraphy from the Gantour basin, Morocco: A proof of concept from the K–Pg transition to mid-Thanetian. Chemical Geology, 2024, 644, pp.121861. ⟨10.1016/j.chemgeo.2023.121861⟩. ⟨insu-04328305⟩
DOI
https://doi.org/10.1016/j.chemgeo.2023.121861
Funding
['Mohammed VI Polytechnic University (UM6P),', 'University of Montpellier (UM) [UM6P-UM specific agreement n° UM 190775 relating to the UM6P-UM/CNRS framework agreement n° UM 190759]', 'Office Chérifien des Phosphates (OCP) S.A. [OCP-UM6P specific agreement n° 7 “Multi-scale distribution of minor and trace elements in Moroccan phosphate deposits” relating to the OCP-UM6P framework agreement in Sciences & Technology]']
HAL Collection
["INSU - Institut National des Sciences de l'Univers", 'Université des Antilles', 'Université de Rennes 1', 'Université Rennes 2 - Haute Bretagne', 'CNRS - Centre national de la recherche scientifique', 'Géosciences Rennes', 'Géosciences Montpellier', "Observatoire des Sciences de l'Univers de Rennes", 'GIP Bretagne Environnement', 'Publications labos UR1 dans HAL-Rennes 1', 'UR1 - publications SDLM', 'Université Rennes 2', 'Université de Montpellier', 'TEST Université de Rennes CSS', 'Université de Rennes', 'Institut National de Recherche en Agriculture, Alimentation et Environnement', 'Pôle Rennes 1 - Environnement', 'Nanoscale', 'Université de Montpellier (2015-2021)', 'Université de Montpellier - EPE', 'Réseau "Systèmes Agricoles et Eau"', 'Institut écologie et environnement du CNRS']
HAL Identifier
4328305
Institution
["Institut national des sciences de l'Univers", 'Université de Rennes', 'Université de Rennes 2', 'Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement', 'Cardiff University', 'Mohammed VI Polytechnic University', 'European Synchrotron Radiation Facility']
Laboratory
['Géosciences Montpellier', 'Géosciences Rennes']
Published in
France

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