Diagenetic effects in Hf-Nd isotopic compositions on clay fractions: Source-to-sink analysis of signal perturbation in denudation records
| Autor: | Camilo Esteban Gaitan, Emmanuelle Pucéat, Pierre Pellenard, Thierry Adatte, Germain Bayon, Cécile Robin, François Guillocheau |
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| Přispěvatelé: | Biogéosciences [UMR 6282] (BGS), Université de Bourgogne (UB)-Centre National de la Recherche Scientifique (CNRS), Institut des sciences de la terre [Lausanne] (ISTE), Université de Lausanne = University of Lausanne (UNIL), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), European Geosciences Union |
| Jazyk: | angličtina |
| Rok vydání: | 2023 |
| Předmět: | |
| Zdroj: | EGU General Assembly 2023 EGU General Assembly 2023, Apr 2023, Vienna, Austria., pp.EGU23-14972, 2023, ⟨10.5194/egusphere-egu23-14972⟩ |
| Popis: | Recent studies have coupled the Lu-Hf and Sm-Nd isotopic systems on clay fractions to assess the evolution of chemical weathering in both ancient and modern environments. Results of this proxy in the abyssal plain of the Cape Basin in Southwestern Africa show a concomitant increase of chemical weathering and physical erosion in response to a late Cretaceous tectonic uplift. In this study, we performed analyses on sediments in the continental slope of the basin that show significant differences compared to the abyssal plain: A long-steady decrease in quartz simultaneous to an increase in the calcite content during the late Cretaceous; a lower content of detrital smectite throughout the section; and the presence of mixed layer assemblages of illite – smectite (R0 or R1) and vermiculite – chlorite during the early-late Cretaceous transition, coinciding with the period of low carbonate content. First, these differences indicate a variation in the input of siliciclastic material and a change in the carbonate compensation depth. Second, clay assemblages reveal a burial diagenetic influence compared to those recorded in the abyssal domain, likely due to thicker deposition in the continental slope. These diagenetic processes indicate that there is a perturbation in the chemical weathering signal at the continental slope, therefore the disparities between the denudation record on clays in both segments cannot be attributed to an effect of signal propagation due to this post-deposition processes. |
| Databáze: | OpenAIRE |
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