Ice dynamics and ocean productivity during the Late Miocene, offshore Wilkes Land, East Antarctica
The middle Miocene Climatic Transition (~14 Ma) is commonly interpreted to represent the significant advance of the East Antarctic Ice Sheet (EAIS), and the transition to a hyper-arid climate and a stable polar-styled ice sheet. However, an increasing number of studies provide evidence for continued...
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ftvuwellington:oai:researcharchive.vuw.ac.nz:10063/8281 2023-08-15T12:37:33+02:00 Ice dynamics and ocean productivity during the Late Miocene, offshore Wilkes Land, East Antarctica Pretty, Rebecca McKay, Rob Dunbar, Gavin 2019 http://researcharchive.vuw.ac.nz/handle/10063/8281 en_NZ eng Victoria University of Wellington http://researcharchive.vuw.ac.nz/handle/10063/8281 Author Retains Copyright Antarctica Late Miocene Nannofossils text Masters 2019 ftvuwellington 2023-07-25T17:29:01Z The middle Miocene Climatic Transition (~14 Ma) is commonly interpreted to represent the significant advance of the East Antarctic Ice Sheet (EAIS), and the transition to a hyper-arid climate and a stable polar-styled ice sheet. However, an increasing number of studies provide evidence for continued instability and abundant meltwater processes influencing the low-lying margins of the EAIS during the Late Miocene (~11.6-5.3 Ma). The history of the EAIS during this period remains ambiguous due to the sparse number of records, and those that do exist have poor age resolution. This thesis investigates Integrated Ocean Drilling Program Site U1361 (64°24.5°S 143°53.1°E), located on the lowermost continental rise of the Wilkes Land margin. It aims to assess the variability of the EAIS and associated changes in palaeoceanography offshore one of the largest marine-based sectors of East Antarctica, the Wilkes Subglacial Basin, and to establish if the EAIS was responding to orbital forcings during the Late Miocene. The study period (~11.7 to 10.8 Ma) contains six intervals of nannofossil-rich mudstones, interbedded with laminated mudstones and diatom-rich mudstones. Nannofossils are absent elsewhere in core U1361A, which covers the past ~14 Ma. To identify the sedimentary and depositional processes which influenced this anomalous interval of calcareous biological productivity, a high-resolution record (using ~450 samples) of Iceberg Rafted Debris (IBRD), grain size analysis and bulk geochemistry XRF analysis have been developed. A lithofacies scheme has been established and used to provide an interpretation of the shifting sedimentary processes through time. Repeating cycles of faintly laminated mudstones were interpreted to represent the influence of bottom current activity on overbank turbidites, that spill onto a channel leeve, during glacial periods. The contouritic nature of the facies is likely associated with the low-relief channel-levee system at this time. Interglacial sedimentation is characterised by an increase ... Master Thesis Antarc* Antarctic Antarctica East Antarctica Ice Sheet Iceberg* Wilkes Land Victoria University of Wellington: ResearchArchive Antarctic East Antarctic Ice Sheet East Antarctica Wilkes Land ENVELOPE(120.000,120.000,-69.000,-69.000) Wilkes Subglacial Basin ENVELOPE(145.000,145.000,-75.000,-75.000) |
institution |
Open Polar |
collection |
Victoria University of Wellington: ResearchArchive |
op_collection_id |
ftvuwellington |
language |
English |
topic |
Antarctica Late Miocene Nannofossils |
spellingShingle |
Antarctica Late Miocene Nannofossils Pretty, Rebecca Ice dynamics and ocean productivity during the Late Miocene, offshore Wilkes Land, East Antarctica |
topic_facet |
Antarctica Late Miocene Nannofossils |
description |
The middle Miocene Climatic Transition (~14 Ma) is commonly interpreted to represent the significant advance of the East Antarctic Ice Sheet (EAIS), and the transition to a hyper-arid climate and a stable polar-styled ice sheet. However, an increasing number of studies provide evidence for continued instability and abundant meltwater processes influencing the low-lying margins of the EAIS during the Late Miocene (~11.6-5.3 Ma). The history of the EAIS during this period remains ambiguous due to the sparse number of records, and those that do exist have poor age resolution. This thesis investigates Integrated Ocean Drilling Program Site U1361 (64°24.5°S 143°53.1°E), located on the lowermost continental rise of the Wilkes Land margin. It aims to assess the variability of the EAIS and associated changes in palaeoceanography offshore one of the largest marine-based sectors of East Antarctica, the Wilkes Subglacial Basin, and to establish if the EAIS was responding to orbital forcings during the Late Miocene. The study period (~11.7 to 10.8 Ma) contains six intervals of nannofossil-rich mudstones, interbedded with laminated mudstones and diatom-rich mudstones. Nannofossils are absent elsewhere in core U1361A, which covers the past ~14 Ma. To identify the sedimentary and depositional processes which influenced this anomalous interval of calcareous biological productivity, a high-resolution record (using ~450 samples) of Iceberg Rafted Debris (IBRD), grain size analysis and bulk geochemistry XRF analysis have been developed. A lithofacies scheme has been established and used to provide an interpretation of the shifting sedimentary processes through time. Repeating cycles of faintly laminated mudstones were interpreted to represent the influence of bottom current activity on overbank turbidites, that spill onto a channel leeve, during glacial periods. The contouritic nature of the facies is likely associated with the low-relief channel-levee system at this time. Interglacial sedimentation is characterised by an increase ... |
author2 |
McKay, Rob Dunbar, Gavin |
format |
Master Thesis |
author |
Pretty, Rebecca |
author_facet |
Pretty, Rebecca |
author_sort |
Pretty, Rebecca |
title |
Ice dynamics and ocean productivity during the Late Miocene, offshore Wilkes Land, East Antarctica |
title_short |
Ice dynamics and ocean productivity during the Late Miocene, offshore Wilkes Land, East Antarctica |
title_full |
Ice dynamics and ocean productivity during the Late Miocene, offshore Wilkes Land, East Antarctica |
title_fullStr |
Ice dynamics and ocean productivity during the Late Miocene, offshore Wilkes Land, East Antarctica |
title_full_unstemmed |
Ice dynamics and ocean productivity during the Late Miocene, offshore Wilkes Land, East Antarctica |
title_sort |
ice dynamics and ocean productivity during the late miocene, offshore wilkes land, east antarctica |
publisher |
Victoria University of Wellington |
publishDate |
2019 |
url |
http://researcharchive.vuw.ac.nz/handle/10063/8281 |
long_lat |
ENVELOPE(120.000,120.000,-69.000,-69.000) ENVELOPE(145.000,145.000,-75.000,-75.000) |
geographic |
Antarctic East Antarctic Ice Sheet East Antarctica Wilkes Land Wilkes Subglacial Basin |
geographic_facet |
Antarctic East Antarctic Ice Sheet East Antarctica Wilkes Land Wilkes Subglacial Basin |
genre |
Antarc* Antarctic Antarctica East Antarctica Ice Sheet Iceberg* Wilkes Land |
genre_facet |
Antarc* Antarctic Antarctica East Antarctica Ice Sheet Iceberg* Wilkes Land |
op_relation |
http://researcharchive.vuw.ac.nz/handle/10063/8281 |
op_rights |
Author Retains Copyright |
_version_ |
1774294282166861824 |