Foraminiferal taphonomy, palaeoecology and palaeoceanography of the Eocene
Foraminiferal taphonomy, palaeoecology and palaeoceanography of the Eocene
The Eocene Epoch (˜34 to 55 Ma) of Earth history was characterised by warm temperatures, high partial pressures of carbon dioxide in the atmosphere (pCO2[atm]) and by small to non-existent continental ice sheets. Because we are currently heading toward a climate state characterised by warmer mean global temperatures and higher pCO2[atm], it is imperative to understand the nature and causes of climatic variability and carbon cycle behaviour during previous globally warm climates.
The fossil tests of foraminifera are widely used for palaeoceanographic studies. Palaeoecological constraints are established here for diverse late middle Eocene planktic foraminiferal assemblages, which include many rare species and some previously undocumented morphotypes. The diversity of palaeoecologies highlights the potential for reconstructing the temporal evolution of upper ocean physical and chemical structures in the Palaeogene using a multiple species approach. In addition, an assessment is made of the microstructural preservation of Eocene foraminiferal tests, with the aim of developing a more quantitative estimate of the degree of diagenetic alteration in ancient foraminiferal calcite. This work has implications for the robustness of the geochemical proxy palaeoceanographic signals contained within their tests.
The Eocene Epoch represents over one third of the entire Cenozoic Era. Yet virtually nothing is known of the magnitude and stability of Eocene warmth and carbon cycling on anything but a long-term (multi-million year) time-scale. This problem is addressed by using Eocene sedimentary sections recently recovered from Demerara Rise, offshore Surinam, during ODP Leg 207. A new early to middle Eocene benthic foraminiferal stable isotope stratigraphy (˜100 kyr resolution) from Demerara Rise is broadly consistent at the Myr time-scale with a composite record based on multiple sites (Zachos et al, 2001a). The overall form of a preliminary benthic foraminiferal middle Eocene Mg/Ca record is similar to the oxygen isotope record and in support of long-term middle Eocene cooling.
University of Southampton
Sexton, Philip
836b46d0-a948-4366-8cf6-73b7d30e651b
2005
Sexton, Philip
836b46d0-a948-4366-8cf6-73b7d30e651b
Wilson, Paul
f940a9f0-fa5a-4a64-9061-f0794bfbf7c6
Sexton, Philip
(2005)
Foraminiferal taphonomy, palaeoecology and palaeoceanography of the Eocene.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
The Eocene Epoch (˜34 to 55 Ma) of Earth history was characterised by warm temperatures, high partial pressures of carbon dioxide in the atmosphere (pCO2[atm]) and by small to non-existent continental ice sheets. Because we are currently heading toward a climate state characterised by warmer mean global temperatures and higher pCO2[atm], it is imperative to understand the nature and causes of climatic variability and carbon cycle behaviour during previous globally warm climates.
The fossil tests of foraminifera are widely used for palaeoceanographic studies. Palaeoecological constraints are established here for diverse late middle Eocene planktic foraminiferal assemblages, which include many rare species and some previously undocumented morphotypes. The diversity of palaeoecologies highlights the potential for reconstructing the temporal evolution of upper ocean physical and chemical structures in the Palaeogene using a multiple species approach. In addition, an assessment is made of the microstructural preservation of Eocene foraminiferal tests, with the aim of developing a more quantitative estimate of the degree of diagenetic alteration in ancient foraminiferal calcite. This work has implications for the robustness of the geochemical proxy palaeoceanographic signals contained within their tests.
The Eocene Epoch represents over one third of the entire Cenozoic Era. Yet virtually nothing is known of the magnitude and stability of Eocene warmth and carbon cycling on anything but a long-term (multi-million year) time-scale. This problem is addressed by using Eocene sedimentary sections recently recovered from Demerara Rise, offshore Surinam, during ODP Leg 207. A new early to middle Eocene benthic foraminiferal stable isotope stratigraphy (˜100 kyr resolution) from Demerara Rise is broadly consistent at the Myr time-scale with a composite record based on multiple sites (Zachos et al, 2001a). The overall form of a preliminary benthic foraminiferal middle Eocene Mg/Ca record is similar to the oxygen isotope record and in support of long-term middle Eocene cooling.
This record has no associated files available for download.
More information
Published date: 2005
Identifiers
Local EPrints ID: 465577
URI: http://eprints.soton.ac.uk/id/eprint/465577
PURE UUID: c1146b9d-2b24-4a01-959d-d167462a488d
Catalogue record
Date deposited: 05 Jul 2022 01:53
Last modified: 20 Aug 2022 01:36
Export record
Contributors
Author:
Philip Sexton
Download statistics
Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.
View more statistics
