Impact of the Eocene-Oligocene transition on terrestrial ecosystems
The study of past climate changes on the terrestrial realm provides clues to understand the mechanisms,chronology, and timing of ecosystems response to climate disturbances. The Eocene-Oligocene Transition(EOT) of the Eocene-Oligocene boundary (EOb) is well suited for this type of study because it r...
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Other Authors: | , , , , , , , |
Format: | Doctoral or Postdoctoral Thesis |
Language: | French |
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HAL CCSD
2016
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Online Access: | https://theses.hal.science/tel-02441344 https://theses.hal.science/tel-02441344/document https://theses.hal.science/tel-02441344/file/julie-ghirardi_4143.pdf |
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ftinsu:oai:HAL:tel-02441344v1 |
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record_format |
openpolar |
institution |
Open Polar |
collection |
Institut national des sciences de l'Univers: HAL-INSU |
op_collection_id |
ftinsu |
language |
French |
topic |
Biomarkers Isotopes Orbital parameters Solar cycles Climate change EOT Biomarqueurs Paramètres orbitaux Cycles solaires Changement climatique [SDU.STU]Sciences of the Universe [physics]/Earth Sciences |
spellingShingle |
Biomarkers Isotopes Orbital parameters Solar cycles Climate change EOT Biomarqueurs Paramètres orbitaux Cycles solaires Changement climatique [SDU.STU]Sciences of the Universe [physics]/Earth Sciences Ghirardi, Julie Impact of the Eocene-Oligocene transition on terrestrial ecosystems |
topic_facet |
Biomarkers Isotopes Orbital parameters Solar cycles Climate change EOT Biomarqueurs Paramètres orbitaux Cycles solaires Changement climatique [SDU.STU]Sciences of the Universe [physics]/Earth Sciences |
description |
The study of past climate changes on the terrestrial realm provides clues to understand the mechanisms,chronology, and timing of ecosystems response to climate disturbances. The Eocene-Oligocene Transition(EOT) of the Eocene-Oligocene boundary (EOb) is well suited for this type of study because it records the last climatic transition between the greenhouse and icehouse modes via a misunderstood interval: thedoubthouse period. This climatic transition was studied through the analysis of organic-rich lacustrine sediments. After an astro-calibrated age model was set up, we reconstructed the evolution of vegetation by using molecular biomarkers specific of plant groups and of local climate (temperature and hydrological conditions) by using molecular and isotopic proxies. The climate record exhibits a marked cooling and drying at the EOT. The evolution of vegetation did not show any abrupt change but exhibited pronounced and rhythmic changes in phase with excentricity during an interval that started 1750 ka before the EOb and lasted until 300 ka after. This interval named Environmental Transition Interval (ETI) was warmer and wetter, and coincides with the doubthouse period. The start of the ETI is concomitant with changes in the recording of orbital parameters. The good expression of solar cycles in the sediments from that period attests to the setting or strengthening of ocean-atmosphere couplings linked to the establishment of the Antarctic icesheet. This work partly solves the uncertainties that prevailed on the doubthouse period. L’étude de l’impact des changements climatiques passés sur le domaine continental permet de comprendre les mécanismes, les vitesses et le calendrier des réponses des écosystèmes aux perturbations.La Transition Eocène-Oligocène (TEO) de la limite Eocène-Oligocène (EOb) se prête bien à ce type d’étude car elle enregistre la dernière transition climatique entre le mode greenhouse et le mode icehouse en passant par un intervalle mal compris : le doubthouse. Cette transition climatique a ... |
author2 |
Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO) Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC) Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS) Bureau de Recherches Géologiques et Minières (BRGM) (BRGM) Université d'Orléans Christian Di Giovanni |
format |
Doctoral or Postdoctoral Thesis |
author |
Ghirardi, Julie |
author_facet |
Ghirardi, Julie |
author_sort |
Ghirardi, Julie |
title |
Impact of the Eocene-Oligocene transition on terrestrial ecosystems |
title_short |
Impact of the Eocene-Oligocene transition on terrestrial ecosystems |
title_full |
Impact of the Eocene-Oligocene transition on terrestrial ecosystems |
title_fullStr |
Impact of the Eocene-Oligocene transition on terrestrial ecosystems |
title_full_unstemmed |
Impact of the Eocene-Oligocene transition on terrestrial ecosystems |
title_sort |
impact of the eocene-oligocene transition on terrestrial ecosystems |
publisher |
HAL CCSD |
publishDate |
2016 |
url |
https://theses.hal.science/tel-02441344 https://theses.hal.science/tel-02441344/document https://theses.hal.science/tel-02441344/file/julie-ghirardi_4143.pdf |
geographic |
Antarctic The Antarctic |
geographic_facet |
Antarctic The Antarctic |
genre |
Antarc* Antarctic |
genre_facet |
Antarc* Antarctic |
op_source |
https://theses.hal.science/tel-02441344 Sciences de la Terre. Université d'Orléans, 2016. Français. ⟨NNT : 2016ORLE2093⟩ |
op_relation |
NNT: 2016ORLE2093 tel-02441344 https://theses.hal.science/tel-02441344 https://theses.hal.science/tel-02441344/document https://theses.hal.science/tel-02441344/file/julie-ghirardi_4143.pdf |
op_rights |
info:eu-repo/semantics/OpenAccess |
_version_ |
1788067441056677888 |
spelling |
ftinsu:oai:HAL:tel-02441344v1 2024-01-14T10:01:41+01:00 Impact of the Eocene-Oligocene transition on terrestrial ecosystems Impact de la transition climatique Eocène - Oligocène sur les écosystèmes continentaux : Etude du bassin de Rennes Ghirardi, Julie Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO) Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC) Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS) Bureau de Recherches Géologiques et Minières (BRGM) (BRGM) Université d'Orléans Christian Di Giovanni 2016-11-04 https://theses.hal.science/tel-02441344 https://theses.hal.science/tel-02441344/document https://theses.hal.science/tel-02441344/file/julie-ghirardi_4143.pdf fr fre HAL CCSD NNT: 2016ORLE2093 tel-02441344 https://theses.hal.science/tel-02441344 https://theses.hal.science/tel-02441344/document https://theses.hal.science/tel-02441344/file/julie-ghirardi_4143.pdf info:eu-repo/semantics/OpenAccess https://theses.hal.science/tel-02441344 Sciences de la Terre. Université d'Orléans, 2016. Français. ⟨NNT : 2016ORLE2093⟩ Biomarkers Isotopes Orbital parameters Solar cycles Climate change EOT Biomarqueurs Paramètres orbitaux Cycles solaires Changement climatique [SDU.STU]Sciences of the Universe [physics]/Earth Sciences info:eu-repo/semantics/doctoralThesis Theses 2016 ftinsu 2023-12-20T17:25:58Z The study of past climate changes on the terrestrial realm provides clues to understand the mechanisms,chronology, and timing of ecosystems response to climate disturbances. The Eocene-Oligocene Transition(EOT) of the Eocene-Oligocene boundary (EOb) is well suited for this type of study because it records the last climatic transition between the greenhouse and icehouse modes via a misunderstood interval: thedoubthouse period. This climatic transition was studied through the analysis of organic-rich lacustrine sediments. After an astro-calibrated age model was set up, we reconstructed the evolution of vegetation by using molecular biomarkers specific of plant groups and of local climate (temperature and hydrological conditions) by using molecular and isotopic proxies. The climate record exhibits a marked cooling and drying at the EOT. The evolution of vegetation did not show any abrupt change but exhibited pronounced and rhythmic changes in phase with excentricity during an interval that started 1750 ka before the EOb and lasted until 300 ka after. This interval named Environmental Transition Interval (ETI) was warmer and wetter, and coincides with the doubthouse period. The start of the ETI is concomitant with changes in the recording of orbital parameters. The good expression of solar cycles in the sediments from that period attests to the setting or strengthening of ocean-atmosphere couplings linked to the establishment of the Antarctic icesheet. This work partly solves the uncertainties that prevailed on the doubthouse period. L’étude de l’impact des changements climatiques passés sur le domaine continental permet de comprendre les mécanismes, les vitesses et le calendrier des réponses des écosystèmes aux perturbations.La Transition Eocène-Oligocène (TEO) de la limite Eocène-Oligocène (EOb) se prête bien à ce type d’étude car elle enregistre la dernière transition climatique entre le mode greenhouse et le mode icehouse en passant par un intervalle mal compris : le doubthouse. Cette transition climatique a ... Doctoral or Postdoctoral Thesis Antarc* Antarctic Institut national des sciences de l'Univers: HAL-INSU Antarctic The Antarctic |