Impact of the African monsoon variations on silicate chemical weathering in the Nile basin
This thesis presents a reconstruction of the chemical weathering in the Nile basin since 100.000 years. His objective is to better understand the impact of climatic variations on chemical weathering, to better. This work is based on the geochemistry study on marine core recorded in the Nile delta, o...
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Format: | Doctoral or Postdoctoral Thesis |
Language: | French |
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ftunivcotedazur:oai:HAL:tel-01729331v1 2024-01-07T09:45:20+01:00 Impact of the African monsoon variations on silicate chemical weathering in the Nile basin Impact des variations de la mousson Africaine sur l’érosion chimique des silicates dans le bassin versant du Nil depuis 100.000 ans Bastian, Luc Géoazur (GEOAZUR 7329) Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD France-Sud ) COMUE Université Côte d'Azur (2015 - 2019) Marie Revel Nathalie Vigier 2017-12-07 https://theses.hal.science/tel-01729331 https://theses.hal.science/tel-01729331/document https://theses.hal.science/tel-01729331/file/2017AZUR4101.pdf fr fre HAL CCSD NNT: 2017AZUR4101 tel-01729331 https://theses.hal.science/tel-01729331 https://theses.hal.science/tel-01729331/document https://theses.hal.science/tel-01729331/file/2017AZUR4101.pdf info:eu-repo/semantics/OpenAccess https://theses.hal.science/tel-01729331 Sciences de la Terre. COMUE Université Côte d'Azur (2015 - 2019), 2017. Français. ⟨NNT : 2017AZUR4101⟩ Chemical weathering Nile African monsoon Lithium Neodymium Isotopes Érosion chimique Nil Mousson africaine Neodyme [SDU.STU]Sciences of the Universe [physics]/Earth Sciences info:eu-repo/semantics/doctoralThesis Theses 2017 ftunivcotedazur 2023-12-12T23:44:37Z This thesis presents a reconstruction of the chemical weathering in the Nile basin since 100.000 years. His objective is to better understand the impact of climatic variations on chemical weathering, to better. This work is based on the geochemistry study on marine core recorded in the Nile delta, on a time scale of 100.000 years. It use a novel approach with the coupling of à source tracer (εNd) and chemical weathering tracers (δ7Li and elementary ratios) on the fine fraction (< 2µm). In addition, it was analyzed samples of each actual Nil sources and a core sample from Tana Lack (Ethiopie). The results of this studies have enabled to reconstruct the chemical weathering variations in the Nile basin since 100.000 years. It show a rapid respond of chemical weathering to climate variations. This was also observed by important impact of North Atlantic climate variations on the decrease of chemical weathering in the Nile basin. At present, the chemical weathering flux and the CO2 consumption of the Ethiopian traps are low comparted to the other basaltic regions, as the Deccan. However, our results show that during the most humid periods (African Humid Period) the CO2 consumption was 2 to 3 time higher than today. This indicates that the Ethiopian traps could be have played a non-negligible role in the global CO2 cycle during the Cenozoic, and principally during the most humid periods in North Africa. Finally, analytical developments have been realized to be able to exploit the lithium isotopes on biogenic carbonates as a new tracer of Nile water flood. The results suggest an influence of “vital” effect and diagenetic process. L’objectif de cette thèse est de déterminer une reconstruction de l’altération continentale dans le bassin du Nil depuis 100.000 ans, afin de mieux comprendre l’impact des variations climatiques sur les sols, les apports à la Méditerranée et le cycle du carbone. Ce travail repose sur une étude géochimique fine des argiles extraites d’archives sédimentaires du delta du Nil sur une échelle ... Doctoral or Postdoctoral Thesis North Atlantic HAL Université Côte d'Azur |
institution |
Open Polar |
collection |
HAL Université Côte d'Azur |
op_collection_id |
ftunivcotedazur |
language |
French |
topic |
Chemical weathering Nile African monsoon Lithium Neodymium Isotopes Érosion chimique Nil Mousson africaine Neodyme [SDU.STU]Sciences of the Universe [physics]/Earth Sciences |
spellingShingle |
Chemical weathering Nile African monsoon Lithium Neodymium Isotopes Érosion chimique Nil Mousson africaine Neodyme [SDU.STU]Sciences of the Universe [physics]/Earth Sciences Bastian, Luc Impact of the African monsoon variations on silicate chemical weathering in the Nile basin |
topic_facet |
Chemical weathering Nile African monsoon Lithium Neodymium Isotopes Érosion chimique Nil Mousson africaine Neodyme [SDU.STU]Sciences of the Universe [physics]/Earth Sciences |
description |
This thesis presents a reconstruction of the chemical weathering in the Nile basin since 100.000 years. His objective is to better understand the impact of climatic variations on chemical weathering, to better. This work is based on the geochemistry study on marine core recorded in the Nile delta, on a time scale of 100.000 years. It use a novel approach with the coupling of à source tracer (εNd) and chemical weathering tracers (δ7Li and elementary ratios) on the fine fraction (< 2µm). In addition, it was analyzed samples of each actual Nil sources and a core sample from Tana Lack (Ethiopie). The results of this studies have enabled to reconstruct the chemical weathering variations in the Nile basin since 100.000 years. It show a rapid respond of chemical weathering to climate variations. This was also observed by important impact of North Atlantic climate variations on the decrease of chemical weathering in the Nile basin. At present, the chemical weathering flux and the CO2 consumption of the Ethiopian traps are low comparted to the other basaltic regions, as the Deccan. However, our results show that during the most humid periods (African Humid Period) the CO2 consumption was 2 to 3 time higher than today. This indicates that the Ethiopian traps could be have played a non-negligible role in the global CO2 cycle during the Cenozoic, and principally during the most humid periods in North Africa. Finally, analytical developments have been realized to be able to exploit the lithium isotopes on biogenic carbonates as a new tracer of Nile water flood. The results suggest an influence of “vital” effect and diagenetic process. L’objectif de cette thèse est de déterminer une reconstruction de l’altération continentale dans le bassin du Nil depuis 100.000 ans, afin de mieux comprendre l’impact des variations climatiques sur les sols, les apports à la Méditerranée et le cycle du carbone. Ce travail repose sur une étude géochimique fine des argiles extraites d’archives sédimentaires du delta du Nil sur une échelle ... |
author2 |
Géoazur (GEOAZUR 7329) Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD France-Sud ) COMUE Université Côte d'Azur (2015 - 2019) Marie Revel Nathalie Vigier |
format |
Doctoral or Postdoctoral Thesis |
author |
Bastian, Luc |
author_facet |
Bastian, Luc |
author_sort |
Bastian, Luc |
title |
Impact of the African monsoon variations on silicate chemical weathering in the Nile basin |
title_short |
Impact of the African monsoon variations on silicate chemical weathering in the Nile basin |
title_full |
Impact of the African monsoon variations on silicate chemical weathering in the Nile basin |
title_fullStr |
Impact of the African monsoon variations on silicate chemical weathering in the Nile basin |
title_full_unstemmed |
Impact of the African monsoon variations on silicate chemical weathering in the Nile basin |
title_sort |
impact of the african monsoon variations on silicate chemical weathering in the nile basin |
publisher |
HAL CCSD |
publishDate |
2017 |
url |
https://theses.hal.science/tel-01729331 https://theses.hal.science/tel-01729331/document https://theses.hal.science/tel-01729331/file/2017AZUR4101.pdf |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_source |
https://theses.hal.science/tel-01729331 Sciences de la Terre. COMUE Université Côte d'Azur (2015 - 2019), 2017. Français. ⟨NNT : 2017AZUR4101⟩ |
op_relation |
NNT: 2017AZUR4101 tel-01729331 https://theses.hal.science/tel-01729331 https://theses.hal.science/tel-01729331/document https://theses.hal.science/tel-01729331/file/2017AZUR4101.pdf |
op_rights |
info:eu-repo/semantics/OpenAccess |
_version_ |
1787426845158801408 |