Constraining the greenhouse-icehouse transition during the Paleogene using the geochemistry of the coccoliths
Among the major obstacles in constraining paleoclimates for periods of “greenhouse” type is the poor preservation state of the sedimentary archive, and the existence of limits for each of the different applied geochemical markers. These obstacles lead to great uncertainties on the values and distrib...
Main Author: | |
---|---|
Other Authors: | , , , , , |
Format: | Doctoral or Postdoctoral Thesis |
Language: | French |
Published: |
HAL CCSD
2018
|
Subjects: | |
Online Access: | https://theses.hal.science/tel-02924848 https://theses.hal.science/tel-02924848/document https://theses.hal.science/tel-02924848/file/these_tremblin_maxime_2018.pdf |
id |
ftinsu:oai:HAL:tel-02924848v1 |
---|---|
record_format |
openpolar |
spelling |
ftinsu:oai:HAL:tel-02924848v1 2023-11-05T03:34:30+01:00 Constraining the greenhouse-icehouse transition during the Paleogene using the geochemistry of the coccoliths Contraindre la transition greenhouse-icehouse du Paléogène par la géochimie des coccolithes Tremblin, Maxime Institut des Sciences de la Terre de Paris (iSTeP) Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS) Sorbonne Université Fabrice Minoletti Michaël Hermoso Delphine Desmares 2018-12-07 https://theses.hal.science/tel-02924848 https://theses.hal.science/tel-02924848/document https://theses.hal.science/tel-02924848/file/these_tremblin_maxime_2018.pdf fr fre HAL CCSD NNT: 2018SORUS450 tel-02924848 https://theses.hal.science/tel-02924848 https://theses.hal.science/tel-02924848/document https://theses.hal.science/tel-02924848/file/these_tremblin_maxime_2018.pdf info:eu-repo/semantics/OpenAccess https://theses.hal.science/tel-02924848 Climatologie. Sorbonne Université, 2018. Français. ⟨NNT : 2018SORUS450⟩ Paleoclimates Coccoliths Geochemistry Paleogene Temperatures PCO2 Paléoclimats Coccolithes Géochimie Paléogène Températures [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology [SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology info:eu-repo/semantics/doctoralThesis Theses 2018 ftinsu 2023-10-11T16:35:13Z Among the major obstacles in constraining paleoclimates for periods of “greenhouse” type is the poor preservation state of the sedimentary archive, and the existence of limits for each of the different applied geochemical markers. These obstacles lead to great uncertainties on the values and distribution of sea surface temperatures (SSTs) and atmospheric CO2 concentrations. Therefore, the mechanisms that brought the Earth’s system from a “greenhouse” to an “icehouse” regime throughout the Paleogene are not well constrained. In this thesis, we reconstructed the thermal evolution of the superficial ocean and the evolution of atmospheric pCO2 during the Paleogene from the isotopic signal (δ18O and ∆13C) of the fossilized carbonate exoskeleton of coccolithophores: coccoliths. Our data reveal a global cooling of surface waters from the Early to the Middle Eocene. During the Late Eocene and across the Eocene-Oligocene transition, values for pCO2 decrease, and cooling at high latitudes continues, allowing for the set up of an ice sheet in Antarctic, while the tropical belt warms. This change in the distribution of heat fluxes at the Earth’s surface during this period is synchronous to the deepening of the Drake Passage and to the set up of a vigorous Antarctic Circumpolar Current. These results thus highlight the driving role of changing oceanic circulations for climate dynamics during this transition. This thesis also proves the existence of important latitudinal thermal gradients throughout the Paleogene. The hypothesis of a homogeneous distribution of SSTs between the Equator and the poles, which prevails in the literature but remains hard to modelise, can thus be rejected. Un obstacle majeur à la caractérisation des paléoclimats en période de type « greenhouse » tient à la mauvaise préservation des archives sédimentaires et à des limites dans les calibrations des marqueurs géochimiques utilisés. Ces limitations entrainent de grandes incertitudes sur les valeurs et la répartition des températures des eaux de ... Doctoral or Postdoctoral Thesis Antarc* Antarctic Drake Passage Ice Sheet Institut national des sciences de l'Univers: HAL-INSU |
institution |
Open Polar |
collection |
Institut national des sciences de l'Univers: HAL-INSU |
op_collection_id |
ftinsu |
language |
French |
topic |
Paleoclimates Coccoliths Geochemistry Paleogene Temperatures PCO2 Paléoclimats Coccolithes Géochimie Paléogène Températures [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology [SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology |
spellingShingle |
Paleoclimates Coccoliths Geochemistry Paleogene Temperatures PCO2 Paléoclimats Coccolithes Géochimie Paléogène Températures [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology [SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology Tremblin, Maxime Constraining the greenhouse-icehouse transition during the Paleogene using the geochemistry of the coccoliths |
topic_facet |
Paleoclimates Coccoliths Geochemistry Paleogene Temperatures PCO2 Paléoclimats Coccolithes Géochimie Paléogène Températures [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology [SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology |
description |
Among the major obstacles in constraining paleoclimates for periods of “greenhouse” type is the poor preservation state of the sedimentary archive, and the existence of limits for each of the different applied geochemical markers. These obstacles lead to great uncertainties on the values and distribution of sea surface temperatures (SSTs) and atmospheric CO2 concentrations. Therefore, the mechanisms that brought the Earth’s system from a “greenhouse” to an “icehouse” regime throughout the Paleogene are not well constrained. In this thesis, we reconstructed the thermal evolution of the superficial ocean and the evolution of atmospheric pCO2 during the Paleogene from the isotopic signal (δ18O and ∆13C) of the fossilized carbonate exoskeleton of coccolithophores: coccoliths. Our data reveal a global cooling of surface waters from the Early to the Middle Eocene. During the Late Eocene and across the Eocene-Oligocene transition, values for pCO2 decrease, and cooling at high latitudes continues, allowing for the set up of an ice sheet in Antarctic, while the tropical belt warms. This change in the distribution of heat fluxes at the Earth’s surface during this period is synchronous to the deepening of the Drake Passage and to the set up of a vigorous Antarctic Circumpolar Current. These results thus highlight the driving role of changing oceanic circulations for climate dynamics during this transition. This thesis also proves the existence of important latitudinal thermal gradients throughout the Paleogene. The hypothesis of a homogeneous distribution of SSTs between the Equator and the poles, which prevails in the literature but remains hard to modelise, can thus be rejected. Un obstacle majeur à la caractérisation des paléoclimats en période de type « greenhouse » tient à la mauvaise préservation des archives sédimentaires et à des limites dans les calibrations des marqueurs géochimiques utilisés. Ces limitations entrainent de grandes incertitudes sur les valeurs et la répartition des températures des eaux de ... |
author2 |
Institut des Sciences de la Terre de Paris (iSTeP) Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS) Sorbonne Université Fabrice Minoletti Michaël Hermoso Delphine Desmares |
format |
Doctoral or Postdoctoral Thesis |
author |
Tremblin, Maxime |
author_facet |
Tremblin, Maxime |
author_sort |
Tremblin, Maxime |
title |
Constraining the greenhouse-icehouse transition during the Paleogene using the geochemistry of the coccoliths |
title_short |
Constraining the greenhouse-icehouse transition during the Paleogene using the geochemistry of the coccoliths |
title_full |
Constraining the greenhouse-icehouse transition during the Paleogene using the geochemistry of the coccoliths |
title_fullStr |
Constraining the greenhouse-icehouse transition during the Paleogene using the geochemistry of the coccoliths |
title_full_unstemmed |
Constraining the greenhouse-icehouse transition during the Paleogene using the geochemistry of the coccoliths |
title_sort |
constraining the greenhouse-icehouse transition during the paleogene using the geochemistry of the coccoliths |
publisher |
HAL CCSD |
publishDate |
2018 |
url |
https://theses.hal.science/tel-02924848 https://theses.hal.science/tel-02924848/document https://theses.hal.science/tel-02924848/file/these_tremblin_maxime_2018.pdf |
genre |
Antarc* Antarctic Drake Passage Ice Sheet |
genre_facet |
Antarc* Antarctic Drake Passage Ice Sheet |
op_source |
https://theses.hal.science/tel-02924848 Climatologie. Sorbonne Université, 2018. Français. ⟨NNT : 2018SORUS450⟩ |
op_relation |
NNT: 2018SORUS450 tel-02924848 https://theses.hal.science/tel-02924848 https://theses.hal.science/tel-02924848/document https://theses.hal.science/tel-02924848/file/these_tremblin_maxime_2018.pdf |
op_rights |
info:eu-repo/semantics/OpenAccess |
_version_ |
1781704756724498432 |