Marine Palynomorphs from the Plio-Pleistocene interval of the AND-1B Drill-Core McMurdo Sound, Antarctica
The ANDRILL project recovered over 600 m of Plio-Pleistocene sediments within the Ross embayment, Antarctica. These sediments contain a record of local and regional paleoenvironmental conditions and glacial dynamism. They also provide a proxy for ice dynamics of the West Antarctic Ice Sheet (WAIS) d...
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2010
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Online Access: | https://doi.org/10.26686/wgtn.16992964.v1 |
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ftsmithonian:oai:figshare.com:article/16992964 |
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openpolar |
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Open Polar |
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Earth Sciences not elsewhere classified Palynomorphs Antarctica Pliocene School: School of Geography Environment and Earth Sciences 049999 Earth Sciences not elsewhere classified Marsden: 260104 Sedimentology Marsden: 260113 Palynology Degree Discipline: Geology Degree Level: Masters Degree Name: Master of Science |
spellingShingle |
Earth Sciences not elsewhere classified Palynomorphs Antarctica Pliocene School: School of Geography Environment and Earth Sciences 049999 Earth Sciences not elsewhere classified Marsden: 260104 Sedimentology Marsden: 260113 Palynology Degree Discipline: Geology Degree Level: Masters Degree Name: Master of Science Mearns, Rory Matthew (11683693) Marine Palynomorphs from the Plio-Pleistocene interval of the AND-1B Drill-Core McMurdo Sound, Antarctica |
topic_facet |
Earth Sciences not elsewhere classified Palynomorphs Antarctica Pliocene School: School of Geography Environment and Earth Sciences 049999 Earth Sciences not elsewhere classified Marsden: 260104 Sedimentology Marsden: 260113 Palynology Degree Discipline: Geology Degree Level: Masters Degree Name: Master of Science |
description |
The ANDRILL project recovered over 600 m of Plio-Pleistocene sediments within the Ross embayment, Antarctica. These sediments contain a record of local and regional paleoenvironmental conditions and glacial dynamism. They also provide a proxy for ice dynamics of the West Antarctic Ice Sheet (WAIS) during a period when global temperatures were ~3OC higher than modern. This unique record provides an analogue for future global climate change, which is expected to rise by 3OC by the end of the 21st century. Sixty-one samples from the upper 600 m of the AND-1B core were analysed for their palynomorph content yielding 4 to 5380 grains per sample (with an average frequency of 34 grains per gram). Marine palynomorphs including fossil dinoflagellate cysts, acritarchs, and prasinophyte algae were the focus of this study and fluctuations in their abundance and diversity reflect changes in paleoenvironment and glacial dynamics. The upper 600 m can be divided into 6 discrete units based on the palynomorph assemblage: The early-Pliocene (~5.0 – 4.6 Ma. Unit 1) is characterised by relatively high abundances of in situ round brown dinoflagellate cysts, microforaminiferal linings, and Leiosphaeridia, suggesting warmer than modern paleoenvironmental conditions and seasonal ice within the Ross embayment. The WAIS was likely small and highly dynamic during Unit 1. The mid-Pliocene (~4.6 – 3.4 Ma. Unit 2) exhibits relatively high abundances of round brown dinoflagellate cysts, microforaminiferal linings, and scolecodonts. The relatively low abundance of Leiosphaeridia (understood to indicate proximal/seasonal ice) suggests that ice free conditions at the drill site may have existed for up to ~1.2 Ma and that this may be the warmest period recorded in the core. During the warm, mid-Pliocene interval a sudden increase in scolecodonts (fossilized polychaete remains) may give indications into the water depth at the drill site because of their dependence on physical disturbance (decreasing with depth) for population growth. Further study of the scolecodonts is required before confident estimates of water depth can be made. The mid- to late-Pliocene (~3.4 – 2.6 Ma. Units 3, 4 & 5) is characterised by a variable palynomorph assemblage indicating variability in paleoenvironmental conditions, ice cover at the drill site, and ultimately a variable WAIS. A spike in the prasinophyte alga Cymatiosphaera (understood to indicate reduced salinity) at the base of a diatomite unit in the late-Pliocene may be a record of algae thriving in meltwater from the collapse of the WAIS. Further highresolution analysis is needed to help resolve this event. The Quaternary interval (~2.6 Ma and younger. Unit 6) is significantly different from previous units and is dominated by reworked Eocene dinoflagellate cysts and acritarchs (the “Transantarctic Flora”). This interval records a period of significant cooling and glacial expansion and the WAIS likely grew to its modern “polar” state. The WAIS may have undergone several collapses during super-interglacial periods in the Pleistocene but if it did it did not persist in its collapsed state for significant periods of time. |
format |
Thesis |
author |
Mearns, Rory Matthew (11683693) |
author_facet |
Mearns, Rory Matthew (11683693) |
author_sort |
Mearns, Rory Matthew (11683693) |
title |
Marine Palynomorphs from the Plio-Pleistocene interval of the AND-1B Drill-Core McMurdo Sound, Antarctica |
title_short |
Marine Palynomorphs from the Plio-Pleistocene interval of the AND-1B Drill-Core McMurdo Sound, Antarctica |
title_full |
Marine Palynomorphs from the Plio-Pleistocene interval of the AND-1B Drill-Core McMurdo Sound, Antarctica |
title_fullStr |
Marine Palynomorphs from the Plio-Pleistocene interval of the AND-1B Drill-Core McMurdo Sound, Antarctica |
title_full_unstemmed |
Marine Palynomorphs from the Plio-Pleistocene interval of the AND-1B Drill-Core McMurdo Sound, Antarctica |
title_sort |
marine palynomorphs from the plio-pleistocene interval of the and-1b drill-core mcmurdo sound, antarctica |
publishDate |
2010 |
url |
https://doi.org/10.26686/wgtn.16992964.v1 |
long_lat |
ENVELOPE(66.067,66.067,-67.867,-67.867) |
geographic |
Antarctic West Antarctic Ice Sheet McMurdo Sound Marsden |
geographic_facet |
Antarctic West Antarctic Ice Sheet McMurdo Sound Marsden |
genre |
Antarc* Antarctic Antarctica Ice Sheet McMurdo Sound |
genre_facet |
Antarc* Antarctic Antarctica Ice Sheet McMurdo Sound |
op_relation |
https://figshare.com/articles/thesis/Marine_Palynomorphs_from_the_Plio-Pleistocene_interval_of_the_AND-1B_Drill-Core_McMurdo_Sound_Antarctica/16992964 doi:10.26686/wgtn.16992964.v1 |
op_rights |
Author Retains Copyright |
op_doi |
https://doi.org/10.26686/wgtn.16992964.v1 |
_version_ |
1766096877372047360 |
spelling |
ftsmithonian:oai:figshare.com:article/16992964 2023-05-15T13:37:42+02:00 Marine Palynomorphs from the Plio-Pleistocene interval of the AND-1B Drill-Core McMurdo Sound, Antarctica Mearns, Rory Matthew (11683693) 2010-01-01T00:00:00Z https://doi.org/10.26686/wgtn.16992964.v1 unknown https://figshare.com/articles/thesis/Marine_Palynomorphs_from_the_Plio-Pleistocene_interval_of_the_AND-1B_Drill-Core_McMurdo_Sound_Antarctica/16992964 doi:10.26686/wgtn.16992964.v1 Author Retains Copyright Earth Sciences not elsewhere classified Palynomorphs Antarctica Pliocene School: School of Geography Environment and Earth Sciences 049999 Earth Sciences not elsewhere classified Marsden: 260104 Sedimentology Marsden: 260113 Palynology Degree Discipline: Geology Degree Level: Masters Degree Name: Master of Science Text Thesis 2010 ftsmithonian https://doi.org/10.26686/wgtn.16992964.v1 2021-12-19T22:05:48Z The ANDRILL project recovered over 600 m of Plio-Pleistocene sediments within the Ross embayment, Antarctica. These sediments contain a record of local and regional paleoenvironmental conditions and glacial dynamism. They also provide a proxy for ice dynamics of the West Antarctic Ice Sheet (WAIS) during a period when global temperatures were ~3OC higher than modern. This unique record provides an analogue for future global climate change, which is expected to rise by 3OC by the end of the 21st century. Sixty-one samples from the upper 600 m of the AND-1B core were analysed for their palynomorph content yielding 4 to 5380 grains per sample (with an average frequency of 34 grains per gram). Marine palynomorphs including fossil dinoflagellate cysts, acritarchs, and prasinophyte algae were the focus of this study and fluctuations in their abundance and diversity reflect changes in paleoenvironment and glacial dynamics. The upper 600 m can be divided into 6 discrete units based on the palynomorph assemblage: The early-Pliocene (~5.0 – 4.6 Ma. Unit 1) is characterised by relatively high abundances of in situ round brown dinoflagellate cysts, microforaminiferal linings, and Leiosphaeridia, suggesting warmer than modern paleoenvironmental conditions and seasonal ice within the Ross embayment. The WAIS was likely small and highly dynamic during Unit 1. The mid-Pliocene (~4.6 – 3.4 Ma. Unit 2) exhibits relatively high abundances of round brown dinoflagellate cysts, microforaminiferal linings, and scolecodonts. The relatively low abundance of Leiosphaeridia (understood to indicate proximal/seasonal ice) suggests that ice free conditions at the drill site may have existed for up to ~1.2 Ma and that this may be the warmest period recorded in the core. During the warm, mid-Pliocene interval a sudden increase in scolecodonts (fossilized polychaete remains) may give indications into the water depth at the drill site because of their dependence on physical disturbance (decreasing with depth) for population growth. Further study of the scolecodonts is required before confident estimates of water depth can be made. The mid- to late-Pliocene (~3.4 – 2.6 Ma. Units 3, 4 & 5) is characterised by a variable palynomorph assemblage indicating variability in paleoenvironmental conditions, ice cover at the drill site, and ultimately a variable WAIS. A spike in the prasinophyte alga Cymatiosphaera (understood to indicate reduced salinity) at the base of a diatomite unit in the late-Pliocene may be a record of algae thriving in meltwater from the collapse of the WAIS. Further highresolution analysis is needed to help resolve this event. The Quaternary interval (~2.6 Ma and younger. Unit 6) is significantly different from previous units and is dominated by reworked Eocene dinoflagellate cysts and acritarchs (the “Transantarctic Flora”). This interval records a period of significant cooling and glacial expansion and the WAIS likely grew to its modern “polar” state. The WAIS may have undergone several collapses during super-interglacial periods in the Pleistocene but if it did it did not persist in its collapsed state for significant periods of time. Thesis Antarc* Antarctic Antarctica Ice Sheet McMurdo Sound Unknown Antarctic West Antarctic Ice Sheet McMurdo Sound Marsden ENVELOPE(66.067,66.067,-67.867,-67.867) |