A Sedimentological Record of Early Miocene Ice Advance and Retreat, AND-2A drill hole, McMurdo Sound, Antarctica
The lowest 501 m (∼1139–638 m) of the AND-2A core from southern McMurdo 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 acc...
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2018
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ftmontclairstuni:oai:digitalcommons.montclair.edu:earth-environ-studies-facpubs-1036 2023-07-23T04:14:38+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, Christopher R. Florindo, Fabio Harwood, David M. Judge, Shelley Krissek, Lawrence Panter, Kurt S. Passchier, Sandra Pekar, Stephen Sandroni, Sonia Talarico, Franco M. 2018-06-08T07:00:00Z application/pdf https://digitalcommons.montclair.edu/earth-environ-studies-facpubs/36 https://digitalcommons.montclair.edu/context/earth-environ-studies-facpubs/article/1036/viewcontent/1780.pdf unknown Montclair State University Digital Commons https://digitalcommons.montclair.edu/earth-environ-studies-facpubs/36 https://digitalcommons.montclair.edu/context/earth-environ-studies-facpubs/article/1036/viewcontent/1780.pdf Department of Earth and Environmental Studies Faculty Scholarship and Creative Works climate change antarctica mcmurdo sound provenance analysis Geology Sedimentology text 2018 ftmontclairstuni 2023-07-03T21:42:22Z The lowest 501 m (∼1139–638 m) of the AND-2A core from southern McMurdo 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 ∼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 ∼21 k.y. precession but in CS3 the frequency is closer to 100 k.y. (consistent with eccentricity), with a ... Text Antarc* Antarctic Antarctica Ice Sheet McMurdo Sound Montclair State University Digital Commons Antarctic The Antarctic McMurdo Sound |
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Open Polar |
collection |
Montclair State University Digital Commons |
op_collection_id |
ftmontclairstuni |
language |
unknown |
topic |
climate change antarctica mcmurdo sound provenance analysis Geology Sedimentology |
spellingShingle |
climate change antarctica mcmurdo sound provenance analysis Geology Sedimentology Field, B. D. Browne, G. H. Fielding, Christopher R. Florindo, Fabio Harwood, David M. Judge, Shelley Krissek, Lawrence Panter, Kurt S. Passchier, Sandra Pekar, Stephen Sandroni, Sonia Talarico, Franco M. A Sedimentological Record of Early Miocene Ice Advance and Retreat, AND-2A drill hole, McMurdo Sound, Antarctica |
topic_facet |
climate change antarctica mcmurdo sound provenance analysis Geology Sedimentology |
description |
The lowest 501 m (∼1139–638 m) of the AND-2A core from southern McMurdo 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 ∼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 ∼21 k.y. precession but in CS3 the frequency is closer to 100 k.y. (consistent with eccentricity), with a ... |
format |
Text |
author |
Field, B. D. Browne, G. H. Fielding, Christopher R. Florindo, Fabio Harwood, David M. Judge, Shelley Krissek, Lawrence Panter, Kurt S. Passchier, Sandra Pekar, Stephen Sandroni, Sonia Talarico, Franco M. |
author_facet |
Field, B. D. Browne, G. H. Fielding, Christopher R. Florindo, Fabio Harwood, David M. Judge, Shelley Krissek, Lawrence Panter, Kurt S. Passchier, Sandra Pekar, Stephen Sandroni, Sonia Talarico, Franco 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 |
publisher |
Montclair State University Digital Commons |
publishDate |
2018 |
url |
https://digitalcommons.montclair.edu/earth-environ-studies-facpubs/36 https://digitalcommons.montclair.edu/context/earth-environ-studies-facpubs/article/1036/viewcontent/1780.pdf |
geographic |
Antarctic The Antarctic McMurdo Sound |
geographic_facet |
Antarctic The Antarctic McMurdo Sound |
genre |
Antarc* Antarctic Antarctica Ice Sheet McMurdo Sound |
genre_facet |
Antarc* Antarctic Antarctica Ice Sheet McMurdo Sound |
op_source |
Department of Earth and Environmental Studies Faculty Scholarship and Creative Works |
op_relation |
https://digitalcommons.montclair.edu/earth-environ-studies-facpubs/36 https://digitalcommons.montclair.edu/context/earth-environ-studies-facpubs/article/1036/viewcontent/1780.pdf |
_version_ |
1772186171810512896 |