A sedimentological record of early Miocene ice advance and retreat, AND-2A drill hole, McMurdo Sound, Antarctica
The lowest 501 m (similar to 1139-638 m) of the AND-2A core from southern Mc-Murdo Sound is the most detailed and complete record of early Miocene sediments in Antarctica and indicates substantial variability in Antarctic ice sheet activity during early Miocene time. There are two main pulses of dia...
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Online Access: | http://hdl.handle.net/2122/12324 https://doi.org/10.1130/GES01592.1 |
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ftingv:oai:www.earth-prints.org:2122/12324 2023-05-15T14:01:37+02:00 A sedimentological record of early Miocene ice advance and retreat, AND-2A drill hole, McMurdo Sound, Antarctica Field, B. D. Browne, G. H. Fielding, C. R. Florindo, Fabio Harwood, D. M. Judge, S. A. Krissek, L. A. Panter, K. S. Passchier, S. Pekar, S. F. Sandroni, S. Talarico, F. M. #PLACEHOLDER_PARENT_METADATA_VALUE# Istituto Nazionale di Geofisica e Vulcanologia (INGV), Sezione AC, Roma, Italia 2018-08 http://hdl.handle.net/2122/12324 https://doi.org/10.1130/GES01592.1 en eng Geosphere 4/14 (2018) http://hdl.handle.net/2122/12324 doi:10.1130/GES01592.1 restricted article 2018 ftingv https://doi.org/10.1130/GES01592.1 2022-07-29T06:07:42Z The lowest 501 m (similar to 1139-638 m) of the AND-2A core from southern Mc-Murdo Sound is the most detailed and complete record of early Miocene sediments in Antarctica and indicates substantial variability in Antarctic ice sheet activity during early Miocene time. There are two main pulses of diamictite accumulation recorded in the core, and three significant intervals with almost no coarse clasts. Each diamictite package comprises several sequences consistent with ice advance-retreat episodes. The oldest phase of diamictite deposition, Composite Sequence 1 (CS1), has evidence for grounded ice at the drill site and has been dated around 20.2-20.1 Ma. It likely coincides with cooling associated with isotope event Mi1aa. This is overlain by a diamictite-free, sandstone-dominated interval, CS2 that includes three coarsening-upward deltaic cycles, is inferred to mark substantial warming, and has an inferred age range between 20.1 and 20.05 Ma. Above this is an interval with variable amounts of diamictite (CS3), with indicators of ice grounding, that is inferred to record ice advance relative to CS2, and is overlain by an similar to 100-m-thick mud-rich interval (CS4) with no sedimentological evidence for direct glacial influence at the drill site (ca. 19.4-18.7 Ma). A third overlying diamictite-rich interval (CS5) overlies an unconformity spanning 18.7-17.8 Ma (coinciding with isotope event Mi1b), and records a return to more ice-influenced conditions at the drill site in late early Miocene time. The overall picture for the early Miocene (spanning the period 20.2-17.35 Ma) is one of ice advance alternating with periods of ice retreat and hence significant global climate fluctuations after the permanent establishment of the Antarctic ice sheet at the Eocene/Oligocene boundary, and preceding the relative warmth of the middle Miocene climatic optimum (ca. 17.5-14.5 Ma). Sedimentary cyclicity in CS1 and CS2 is consistent with similar to 21 k.y. precession but in CS3 the frequency is closer to 100 k.y. (consistent ... Article in Journal/Newspaper Antarc* Antarctic Antarctica Ice Sheet McMurdo Sound Earth-Prints (Istituto Nazionale di Geofisica e Vulcanologia) Antarctic McMurdo Sound The Antarctic Geosphere 14 4 1780 1803 |
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Open Polar |
collection |
Earth-Prints (Istituto Nazionale di Geofisica e Vulcanologia) |
op_collection_id |
ftingv |
language |
English |
description |
The lowest 501 m (similar to 1139-638 m) of the AND-2A core from southern Mc-Murdo Sound is the most detailed and complete record of early Miocene sediments in Antarctica and indicates substantial variability in Antarctic ice sheet activity during early Miocene time. There are two main pulses of diamictite accumulation recorded in the core, and three significant intervals with almost no coarse clasts. Each diamictite package comprises several sequences consistent with ice advance-retreat episodes. The oldest phase of diamictite deposition, Composite Sequence 1 (CS1), has evidence for grounded ice at the drill site and has been dated around 20.2-20.1 Ma. It likely coincides with cooling associated with isotope event Mi1aa. This is overlain by a diamictite-free, sandstone-dominated interval, CS2 that includes three coarsening-upward deltaic cycles, is inferred to mark substantial warming, and has an inferred age range between 20.1 and 20.05 Ma. Above this is an interval with variable amounts of diamictite (CS3), with indicators of ice grounding, that is inferred to record ice advance relative to CS2, and is overlain by an similar to 100-m-thick mud-rich interval (CS4) with no sedimentological evidence for direct glacial influence at the drill site (ca. 19.4-18.7 Ma). A third overlying diamictite-rich interval (CS5) overlies an unconformity spanning 18.7-17.8 Ma (coinciding with isotope event Mi1b), and records a return to more ice-influenced conditions at the drill site in late early Miocene time. The overall picture for the early Miocene (spanning the period 20.2-17.35 Ma) is one of ice advance alternating with periods of ice retreat and hence significant global climate fluctuations after the permanent establishment of the Antarctic ice sheet at the Eocene/Oligocene boundary, and preceding the relative warmth of the middle Miocene climatic optimum (ca. 17.5-14.5 Ma). Sedimentary cyclicity in CS1 and CS2 is consistent with similar to 21 k.y. precession but in CS3 the frequency is closer to 100 k.y. (consistent ... |
author2 |
#PLACEHOLDER_PARENT_METADATA_VALUE# Istituto Nazionale di Geofisica e Vulcanologia (INGV), Sezione AC, Roma, Italia |
format |
Article in Journal/Newspaper |
author |
Field, B. D. Browne, G. H. Fielding, C. R. Florindo, Fabio Harwood, D. M. Judge, S. A. Krissek, L. A. Panter, K. S. Passchier, S. Pekar, S. F. Sandroni, S. Talarico, F. M. |
spellingShingle |
Field, B. D. Browne, G. H. Fielding, C. R. Florindo, Fabio Harwood, D. M. Judge, S. A. Krissek, L. A. Panter, K. S. Passchier, S. Pekar, S. F. Sandroni, S. Talarico, F. M. A sedimentological record of early Miocene ice advance and retreat, AND-2A drill hole, McMurdo Sound, Antarctica |
author_facet |
Field, B. D. Browne, G. H. Fielding, C. R. Florindo, Fabio Harwood, D. M. Judge, S. A. Krissek, L. A. Panter, K. S. Passchier, S. Pekar, S. F. Sandroni, S. Talarico, F. M. |
author_sort |
Field, B. D. |
title |
A sedimentological record of early Miocene ice advance and retreat, AND-2A drill hole, McMurdo Sound, Antarctica |
title_short |
A sedimentological record of early Miocene ice advance and retreat, AND-2A drill hole, McMurdo Sound, Antarctica |
title_full |
A sedimentological record of early Miocene ice advance and retreat, AND-2A drill hole, McMurdo Sound, Antarctica |
title_fullStr |
A sedimentological record of early Miocene ice advance and retreat, AND-2A drill hole, McMurdo Sound, Antarctica |
title_full_unstemmed |
A sedimentological record of early Miocene ice advance and retreat, AND-2A drill hole, McMurdo Sound, Antarctica |
title_sort |
sedimentological record of early miocene ice advance and retreat, and-2a drill hole, mcmurdo sound, antarctica |
publishDate |
2018 |
url |
http://hdl.handle.net/2122/12324 https://doi.org/10.1130/GES01592.1 |
geographic |
Antarctic McMurdo Sound The Antarctic |
geographic_facet |
Antarctic McMurdo Sound The Antarctic |
genre |
Antarc* Antarctic Antarctica Ice Sheet McMurdo Sound |
genre_facet |
Antarc* Antarctic Antarctica Ice Sheet McMurdo Sound |
op_relation |
Geosphere 4/14 (2018) http://hdl.handle.net/2122/12324 doi:10.1130/GES01592.1 |
op_rights |
restricted |
op_doi |
https://doi.org/10.1130/GES01592.1 |
container_title |
Geosphere |
container_volume |
14 |
container_issue |
4 |
container_start_page |
1780 |
op_container_end_page |
1803 |
_version_ |
1766271573852946432 |