A New Bathymetric Compilation Highlighting Extensive Paleo–ice Sheet Drainage on the Continental Shelf, South Georgia, Sub-Antarctica
A grid derived from a new compilation of marine echo-sounding data sets has allowed us to visualize and map the geomorphology of the entire continental shelf around South Georgia at an unprecedented level of detail. The grid is the first continuous bathymetric data set covering South Georgia to incl...
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Digital Commons @ University of South Florida
2008
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ftunisfloridatam:oai:digitalcommons.usf.edu:msc_facpub-2581 2023-05-15T14:04:11+02:00 A New Bathymetric Compilation Highlighting Extensive Paleo–ice Sheet Drainage on the Continental Shelf, South Georgia, Sub-Antarctica Graham, Alastair G. C. Fretwell, Peter T. Larter, Robert D. Hodgson, Dominic A. Wilson, Christian K. Tate, Alex J. Morris, Peter 2008-01-01T08:00:00Z application/pdf https://digitalcommons.usf.edu/msc_facpub/1521 https://digitalcommons.usf.edu/cgi/viewcontent.cgi?article=2581&context=msc_facpub unknown Digital Commons @ University of South Florida https://digitalcommons.usf.edu/msc_facpub/1521 https://digitalcommons.usf.edu/cgi/viewcontent.cgi?article=2581&context=msc_facpub default Marine Science Faculty Publications sub-Antarctica South Georgia ice sheets geomorphology moraines bathymetry Life Sciences article 2008 ftunisfloridatam 2022-01-20T18:40:25Z A grid derived from a new compilation of marine echo-sounding data sets has allowed us to visualize and map the geomorphology of the entire continental shelf around South Georgia at an unprecedented level of detail. The grid is the first continuous bathymetric data set covering South Georgia to include multibeam swath bathymetry and represent them at a subkilometer resolution. Large and previously undescribed glacially eroded troughs, linked to South Georgia's modern-day fjords, radiate from the island, marking the former pathways of large outlet glaciers and ice streams. A tectonic or geological influence is apparent for the major troughs, where glaciers have exploited structural weaknesses on the continental block. Bed forms lining the troughs give some first insights into glacial dynamics within the troughs, suggesting arteries of fast flowing ice occupied these topographic depressions in the past and operated over both bedrock and sedimentary substrates. On the outer shelf and within the troughs, large ridges and banks are also common, interpreted as terminal, lateral, and recessional moraines marking former positions of ice sheets on the shelf and their subsequent reorganization during deglaciation. A small trough mouth fan has developed at the mouth of at least one of the cross-shelf troughs, demonstrating a focused sediment delivery to the margin. Slides and slide scars are also present on parts of the margin, showing that margin stability, perhaps also related to glaciation, has been an important factor in depositional processes on the continental slope. Implications of the new observations are that ice sheets have been more extensive on South Georgia than any previous studies have reported. Their age may date back to late Miocene times, and evolution of the shelf system has probably involved numerous late Cenozoic glacial episodes. However, relatively fresh seafloor geomorphology coupled with evidence from other maritime-Antarctic islands (Heard Island and Kerguelen Island) indicating extensive glaciation at the Last Glacial Maximum raises the possibility that the extent of sub-Antarctic glaciation for the Last Glacial period has, until now, been underestimated. Article in Journal/Newspaper Antarc* Antarctic Antarctica Heard Island Ice Sheet Digital Commons University of South Florida (USF) Antarctic Kerguelen Heard Island Kerguelen Island ENVELOPE(69.500,69.500,-49.250,-49.250) |
institution |
Open Polar |
collection |
Digital Commons University of South Florida (USF) |
op_collection_id |
ftunisfloridatam |
language |
unknown |
topic |
sub-Antarctica South Georgia ice sheets geomorphology moraines bathymetry Life Sciences |
spellingShingle |
sub-Antarctica South Georgia ice sheets geomorphology moraines bathymetry Life Sciences Graham, Alastair G. C. Fretwell, Peter T. Larter, Robert D. Hodgson, Dominic A. Wilson, Christian K. Tate, Alex J. Morris, Peter A New Bathymetric Compilation Highlighting Extensive Paleo–ice Sheet Drainage on the Continental Shelf, South Georgia, Sub-Antarctica |
topic_facet |
sub-Antarctica South Georgia ice sheets geomorphology moraines bathymetry Life Sciences |
description |
A grid derived from a new compilation of marine echo-sounding data sets has allowed us to visualize and map the geomorphology of the entire continental shelf around South Georgia at an unprecedented level of detail. The grid is the first continuous bathymetric data set covering South Georgia to include multibeam swath bathymetry and represent them at a subkilometer resolution. Large and previously undescribed glacially eroded troughs, linked to South Georgia's modern-day fjords, radiate from the island, marking the former pathways of large outlet glaciers and ice streams. A tectonic or geological influence is apparent for the major troughs, where glaciers have exploited structural weaknesses on the continental block. Bed forms lining the troughs give some first insights into glacial dynamics within the troughs, suggesting arteries of fast flowing ice occupied these topographic depressions in the past and operated over both bedrock and sedimentary substrates. On the outer shelf and within the troughs, large ridges and banks are also common, interpreted as terminal, lateral, and recessional moraines marking former positions of ice sheets on the shelf and their subsequent reorganization during deglaciation. A small trough mouth fan has developed at the mouth of at least one of the cross-shelf troughs, demonstrating a focused sediment delivery to the margin. Slides and slide scars are also present on parts of the margin, showing that margin stability, perhaps also related to glaciation, has been an important factor in depositional processes on the continental slope. Implications of the new observations are that ice sheets have been more extensive on South Georgia than any previous studies have reported. Their age may date back to late Miocene times, and evolution of the shelf system has probably involved numerous late Cenozoic glacial episodes. However, relatively fresh seafloor geomorphology coupled with evidence from other maritime-Antarctic islands (Heard Island and Kerguelen Island) indicating extensive glaciation at the Last Glacial Maximum raises the possibility that the extent of sub-Antarctic glaciation for the Last Glacial period has, until now, been underestimated. |
format |
Article in Journal/Newspaper |
author |
Graham, Alastair G. C. Fretwell, Peter T. Larter, Robert D. Hodgson, Dominic A. Wilson, Christian K. Tate, Alex J. Morris, Peter |
author_facet |
Graham, Alastair G. C. Fretwell, Peter T. Larter, Robert D. Hodgson, Dominic A. Wilson, Christian K. Tate, Alex J. Morris, Peter |
author_sort |
Graham, Alastair G. C. |
title |
A New Bathymetric Compilation Highlighting Extensive Paleo–ice Sheet Drainage on the Continental Shelf, South Georgia, Sub-Antarctica |
title_short |
A New Bathymetric Compilation Highlighting Extensive Paleo–ice Sheet Drainage on the Continental Shelf, South Georgia, Sub-Antarctica |
title_full |
A New Bathymetric Compilation Highlighting Extensive Paleo–ice Sheet Drainage on the Continental Shelf, South Georgia, Sub-Antarctica |
title_fullStr |
A New Bathymetric Compilation Highlighting Extensive Paleo–ice Sheet Drainage on the Continental Shelf, South Georgia, Sub-Antarctica |
title_full_unstemmed |
A New Bathymetric Compilation Highlighting Extensive Paleo–ice Sheet Drainage on the Continental Shelf, South Georgia, Sub-Antarctica |
title_sort |
new bathymetric compilation highlighting extensive paleo–ice sheet drainage on the continental shelf, south georgia, sub-antarctica |
publisher |
Digital Commons @ University of South Florida |
publishDate |
2008 |
url |
https://digitalcommons.usf.edu/msc_facpub/1521 https://digitalcommons.usf.edu/cgi/viewcontent.cgi?article=2581&context=msc_facpub |
long_lat |
ENVELOPE(69.500,69.500,-49.250,-49.250) |
geographic |
Antarctic Kerguelen Heard Island Kerguelen Island |
geographic_facet |
Antarctic Kerguelen Heard Island Kerguelen Island |
genre |
Antarc* Antarctic Antarctica Heard Island Ice Sheet |
genre_facet |
Antarc* Antarctic Antarctica Heard Island Ice Sheet |
op_source |
Marine Science Faculty Publications |
op_relation |
https://digitalcommons.usf.edu/msc_facpub/1521 https://digitalcommons.usf.edu/cgi/viewcontent.cgi?article=2581&context=msc_facpub |
op_rights |
default |
_version_ |
1766275209931784192 |