Pauline Corentin PhD thesis
Started in october 2018
Late Cretaceous continental weathering evolution on the southern Atlantic margins of Africa and South America: contributions of a new geochemical tracer (combined Lu-Hf and Sm-Nd isotopic systems) coupled with the clay mineralogy
Funding: doctoral grant
Supervisors: Emmanuelle Pucéat ; cosupervisor: Pierre Pellenard
Defended the 29 april 2022
Abstract
The late Cretaceous records a pronounced decrease in temperatures on a global scale between 90 and 65 million years that marks the first step of the progressive climatic decline ultimately leading to our modern climate mode. This first cooling step is concomitant to a major tectonic uplift of the east South American and west African margins. The main objective of this project is to explore the potentially determinant impact of this tectonic uplift on the long-term cooling of the late Cretaceous. A new proxy, based on the coupled Lu-Hf and Sm-Nd isotope systems in clays, will be used to track the late Cretaceous continental weathering evolution on those margins, associated to clay mineralogy that tracks the hydrolysis and mechanical erosion variations. The three IODP sites studied have thus made it possible to show that in the late Cretaceous, the chemical alteration of silicates was intensified in response to the uplifts of the margins but that this response depended on the climatic and tectonic context and illustrated the competition between tectonics and climate on the continental chemical weathering of silicates. Finally, the concomitant evolution between the intensification of the weathering of the margins and the acceleration of the cooling suggests a contribution of the uplift to the late Cretaceous global climate cooling through an increased CO2 consumption engendered by silicates chemical weathering.
Keywords
continental weathering – isotopic geochemistry – clay mineralogy – palaeoclimate – Cretaceous
Thesis advisory panel
Thierry Adatte
Germain Bayon
Jury
Nathalie Fagel, université de Liège, Belgique – reviewer
Christian France-Lanord, CRPG, Nancy – reviewer
Cécile RObin, université de Rennes 1 – examiner
Jérôme Gaillardet, IPGP, Paris – examiner
Nathalie Vigier, Laboratoire d’océanographie de Villefranche – examiner
Emmanuelle Pucéat, université Bourgogne Franche-Comté – supervisor
Pierre Pellenard, université Bourgogne Franche-Comté – cosupervisor
Michel Guiraud, université Bourgogne Franche-Comté – invited
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- kc_raw_content:
Started in october 2018 Late Cretaceous continental weathering evolution on the southern Atlantic margins of Africa and South America: contributions of a new geochemical tracer (combined Lu-Hf and Sm-Nd isotopic systems) coupled with the clay mineralogy
Funding: doctoral grant
Supervisors: Emmanuelle Pucéat ; cosupervisor: Pierre Pellenard
Defended the 29 april 2022
Abstract
The late Cretaceous records a pronounced decrease in temperatures on a global scale between 90 and 65 million years that marks the first step of the progressive climatic decline ultimately leading to our modern climate mode. This first cooling step is concomitant to a major tectonic uplift of the east South American and west African margins. The main objective of this project is to explore the potentially determinant impact of this tectonic uplift on the long-term cooling of the late Cretaceous. A new proxy, based on the coupled Lu-Hf and Sm-Nd isotope systems in clays, will be used to track the late Cretaceous continental weathering evolution on those margins, associated to clay mineralogy that tracks the hydrolysis and mechanical erosion variations. The three IODP sites studied have thus made it possible to show that in the late Cretaceous, the chemical alteration of silicates was intensified in response to the uplifts of the margins but that this response depended on the climatic and tectonic context and illustrated the competition between tectonics and climate on the continental chemical weathering of silicates. Finally, the concomitant evolution between the intensification of the weathering of the margins and the acceleration of the cooling suggests a contribution of the uplift to the late Cretaceous global climate cooling through an increased CO2 consumption engendered by silicates chemical weathering.
Keywords
continental weathering – isotopic geochemistry – clay mineralogy – palaeoclimate – Cretaceous
Thesis advisory panel
Thierry Adatte
Germain BayonJury
Nathalie Fagel, université de Liège, Belgique – reviewer
Christian France-Lanord, CRPG, Nancy – reviewer
Cécile RObin, université de Rennes 1 – examiner
Jérôme Gaillardet, IPGP, Paris – examiner
Nathalie Vigier, Laboratoire d’océanographie de Villefranche – examiner
Emmanuelle Pucéat, université Bourgogne Franche-Comté – supervisor
Pierre Pellenard, université Bourgogne Franche-Comté – cosupervisor
Michel Guiraud, université Bourgogne Franche-Comté – invited- extrait:
- lien_externe:
- titre:
- Evolution de l’altération continentale au cours du Crétacé supérieur sur la marge africaine : application d’un nouveau traceur géochimique (systèmes isotopiques combinés Lu-Hf et Sm-Nd) couplé à la minéralogie des argiles
- date_de_debut:
- octobre 2018
- titre_these:
- Evolution de l’altération continentale au cours du Crétacé supérieur sur la marge africaine : application d’un nouveau traceur géochimique (systèmes isotopiques combinés Lu-Hf et Sm-Nd) couplé à la minéralogie des argiles
- date_de_debut_these:
- octobre 2018
- nom:
- Corentin
- date_de_debut_these_numerique:
- 201810