Cenozoic Antarctic climate evolution based on molecular and isotopic biomarker reconstructions from geological archives in the Ross Sea region
During the Cenozoic Era (the last 65 Ma), Antarctica’s climate has evolved from ice free conditions of the ‘Greenhouse world’, which at its peak (~ 55 Ma) supported near-tropical forests, to the ‘Icehouse’ climate of today with permanent ice sheets, and a very sparse macroflora. This long-term cooli...
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ftvictoriauwfig:oai:figshare.com:article/17064191 2023-05-15T13:35:14+02:00 Cenozoic Antarctic climate evolution based on molecular and isotopic biomarker reconstructions from geological archives in the Ross Sea region Bella Duncan 2017-01-01T00:00:00Z https://doi.org/10.26686/wgtn.17064191.v1 https://figshare.com/articles/thesis/Cenozoic_Antarctic_climate_evolution_based_on_molecular_and_isotopic_biomarker_reconstructions_from_geological_archives_in_the_Ross_Sea_region/17064191 unknown doi:10.26686/wgtn.17064191.v1 https://figshare.com/articles/thesis/Cenozoic_Antarctic_climate_evolution_based_on_molecular_and_isotopic_biomarker_reconstructions_from_geological_archives_in_the_Ross_Sea_region/17064191 Author Retains Copyright Organic Geochemistry Palaeoclimatology Antarctica Biomarkers Paleoclimate School: School of Geography Environment and Earth Sciences Unit: Antarctic Research Centre 040204 Organic Geochemistry 040605 Palaeoclimatology 960306 Effects of Climate Change and Variability on Antarctic and Sub-Antarctic Environments (excl. Social Impacts) 970104 Expanding Knowledge in the Earth Sciences Degree Discipline: Geology Degree Level: Doctoral Degree Name: Doctor of Philosophy Text Thesis 2017 ftvictoriauwfig https://doi.org/10.26686/wgtn.17064191.v1 2021-11-25T00:03:47Z During the Cenozoic Era (the last 65 Ma), Antarctica’s climate has evolved from ice free conditions of the ‘Greenhouse world’, which at its peak (~ 55 Ma) supported near-tropical forests, to the ‘Icehouse’ climate of today with permanent ice sheets, and a very sparse macroflora. This long-term cooling trend is punctuated by a number of major, abrupt, and in some cases, irreversible climate transitions. Reconstructing past changes in vegetation, sea surface temperature, hydroclimate and the carbon cycle require robust geological proxies that in turn can provide insights into climatic thresholds and feedbacks that drove major transitions in the evolution of Antarctica’s ice sheets. Biomarkers allow climate and environmental proxy reconstructions for this region, where other more traditional paleoclimate methods are less suitable. This study has two aims. Firstly to assess the suitability and applicability of biomarkers in Antarctic sediments across a range of depositional settings and ages, and secondly to apply biomarker-based climate proxies to reconstruct environmental and climate conditions during key periods in the development of the Antarctic Ice Sheets. The distribution and abundances of n-alkanes are assessed in Oligocene and Miocene sediments from a terrestrial outcrop locality in the Transantarctic Mountains, and two glaciomarine sediment cores and an ice-distal deep marine core from the western Ross Sea. Comparisons are made with n-alkane distributions in Eocene glacial erratics and sedimentary rocks of the Mesozoic Beacon Supergroup, both likely sources of reworked material. A shift in dominant chain length from n-C₂₉ to n-C₂₇ occurs between the Late Eocene and Early Oligocene, considered a response to a significant climate cooling. Samples from glaciofluvial environments onshore, and subglacial and ice-proximal environments offshore display a reworked n-alkane distribution, characterised by low carbon preference index (CPI), high average chain length (ACL) and high n-C₂₉/n-C₂₇ values. Whereas, samples ... Thesis Antarc* Antarctic Antarctica Ross Sea Open Access Victoria University of Wellington / Te Herenga Waka Antarctic The Antarctic Ross Sea Transantarctic Mountains |
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Open Polar |
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Open Access Victoria University of Wellington / Te Herenga Waka |
op_collection_id |
ftvictoriauwfig |
language |
unknown |
topic |
Organic Geochemistry Palaeoclimatology Antarctica Biomarkers Paleoclimate School: School of Geography Environment and Earth Sciences Unit: Antarctic Research Centre 040204 Organic Geochemistry 040605 Palaeoclimatology 960306 Effects of Climate Change and Variability on Antarctic and Sub-Antarctic Environments (excl. Social Impacts) 970104 Expanding Knowledge in the Earth Sciences Degree Discipline: Geology Degree Level: Doctoral Degree Name: Doctor of Philosophy |
spellingShingle |
Organic Geochemistry Palaeoclimatology Antarctica Biomarkers Paleoclimate School: School of Geography Environment and Earth Sciences Unit: Antarctic Research Centre 040204 Organic Geochemistry 040605 Palaeoclimatology 960306 Effects of Climate Change and Variability on Antarctic and Sub-Antarctic Environments (excl. Social Impacts) 970104 Expanding Knowledge in the Earth Sciences Degree Discipline: Geology Degree Level: Doctoral Degree Name: Doctor of Philosophy Bella Duncan Cenozoic Antarctic climate evolution based on molecular and isotopic biomarker reconstructions from geological archives in the Ross Sea region |
topic_facet |
Organic Geochemistry Palaeoclimatology Antarctica Biomarkers Paleoclimate School: School of Geography Environment and Earth Sciences Unit: Antarctic Research Centre 040204 Organic Geochemistry 040605 Palaeoclimatology 960306 Effects of Climate Change and Variability on Antarctic and Sub-Antarctic Environments (excl. Social Impacts) 970104 Expanding Knowledge in the Earth Sciences Degree Discipline: Geology Degree Level: Doctoral Degree Name: Doctor of Philosophy |
description |
During the Cenozoic Era (the last 65 Ma), Antarctica’s climate has evolved from ice free conditions of the ‘Greenhouse world’, which at its peak (~ 55 Ma) supported near-tropical forests, to the ‘Icehouse’ climate of today with permanent ice sheets, and a very sparse macroflora. This long-term cooling trend is punctuated by a number of major, abrupt, and in some cases, irreversible climate transitions. Reconstructing past changes in vegetation, sea surface temperature, hydroclimate and the carbon cycle require robust geological proxies that in turn can provide insights into climatic thresholds and feedbacks that drove major transitions in the evolution of Antarctica’s ice sheets. Biomarkers allow climate and environmental proxy reconstructions for this region, where other more traditional paleoclimate methods are less suitable. This study has two aims. Firstly to assess the suitability and applicability of biomarkers in Antarctic sediments across a range of depositional settings and ages, and secondly to apply biomarker-based climate proxies to reconstruct environmental and climate conditions during key periods in the development of the Antarctic Ice Sheets. The distribution and abundances of n-alkanes are assessed in Oligocene and Miocene sediments from a terrestrial outcrop locality in the Transantarctic Mountains, and two glaciomarine sediment cores and an ice-distal deep marine core from the western Ross Sea. Comparisons are made with n-alkane distributions in Eocene glacial erratics and sedimentary rocks of the Mesozoic Beacon Supergroup, both likely sources of reworked material. A shift in dominant chain length from n-C₂₉ to n-C₂₇ occurs between the Late Eocene and Early Oligocene, considered a response to a significant climate cooling. Samples from glaciofluvial environments onshore, and subglacial and ice-proximal environments offshore display a reworked n-alkane distribution, characterised by low carbon preference index (CPI), high average chain length (ACL) and high n-C₂₉/n-C₂₇ values. Whereas, samples ... |
format |
Thesis |
author |
Bella Duncan |
author_facet |
Bella Duncan |
author_sort |
Bella Duncan |
title |
Cenozoic Antarctic climate evolution based on molecular and isotopic biomarker reconstructions from geological archives in the Ross Sea region |
title_short |
Cenozoic Antarctic climate evolution based on molecular and isotopic biomarker reconstructions from geological archives in the Ross Sea region |
title_full |
Cenozoic Antarctic climate evolution based on molecular and isotopic biomarker reconstructions from geological archives in the Ross Sea region |
title_fullStr |
Cenozoic Antarctic climate evolution based on molecular and isotopic biomarker reconstructions from geological archives in the Ross Sea region |
title_full_unstemmed |
Cenozoic Antarctic climate evolution based on molecular and isotopic biomarker reconstructions from geological archives in the Ross Sea region |
title_sort |
cenozoic antarctic climate evolution based on molecular and isotopic biomarker reconstructions from geological archives in the ross sea region |
publishDate |
2017 |
url |
https://doi.org/10.26686/wgtn.17064191.v1 https://figshare.com/articles/thesis/Cenozoic_Antarctic_climate_evolution_based_on_molecular_and_isotopic_biomarker_reconstructions_from_geological_archives_in_the_Ross_Sea_region/17064191 |
geographic |
Antarctic The Antarctic Ross Sea Transantarctic Mountains |
geographic_facet |
Antarctic The Antarctic Ross Sea Transantarctic Mountains |
genre |
Antarc* Antarctic Antarctica Ross Sea |
genre_facet |
Antarc* Antarctic Antarctica Ross Sea |
op_relation |
doi:10.26686/wgtn.17064191.v1 https://figshare.com/articles/thesis/Cenozoic_Antarctic_climate_evolution_based_on_molecular_and_isotopic_biomarker_reconstructions_from_geological_archives_in_the_Ross_Sea_region/17064191 |
op_rights |
Author Retains Copyright |
op_doi |
https://doi.org/10.26686/wgtn.17064191.v1 |
_version_ |
1766063291150368768 |