Dynamics Of The Late Plio-Pleistocene West Antarctic Ice Sheet Documented In Subglacial Diamictites, AND-1B Drill Core
Geologic studies of sediment deposited by glaciers can provide crucial insights into the subglacial environment. We studied muddy diamictites in the ANtarctic geological DRILLing (ANDRILL) AND-1B drill core, acquired from beneath the Ross Ice Shelf in McMurdo Sound, with the aim of identifying paleo...
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ftunivnorthcag:oai:libres.uncg.edu/33103 2024-09-30T14:26:49+00:00 Dynamics Of The Late Plio-Pleistocene West Antarctic Ice Sheet Documented In Subglacial Diamictites, AND-1B Drill Core Cowan, Ellen A. NC DOCKS at Appalachian State University 2014 http://libres.uncg.edu/ir/asu/f/Cowan_Ellen_2014_RECAPP_Dynamics of the late Plio.pdf English eng http://libres.uncg.edu/ir/asu/f/Cowan_Ellen_2014_RECAPP_Dynamics of the late Plio.pdf 2014 ftunivnorthcag 2024-09-17T15:09:14Z Geologic studies of sediment deposited by glaciers can provide crucial insights into the subglacial environment. We studied muddy diamictites in the ANtarctic geological DRILLing (ANDRILL) AND-1B drill core, acquired from beneath the Ross Ice Shelf in McMurdo Sound, with the aim of identifying paleo-ice stream activity in the Plio– Pleistocene. Glacial advances were identified from glacial surfaces of erosion (GSEs) and subglacial diamictites within three complete sequences were investigated using lithofacies associations, micromorphology, and quartz sand grain microtextures. Whereas conditions in the Late Pliocene resemble the modern Greenland Ice Sheet where fast flowing glaciers lubricated by surface meltwater terminate directly in the sea (interval 201–212 mbsl) conditions in the Late Pleistocene are similar to modern West Antarctic Ice Sheet (WAIS) ice streams (38–49 mbsl). We identify the latter from ductile deformation and high pore-water pressure, which resulted in pervasive rotation and formation of till pellets and low relief, rounded sand grains dominated by abrasion. In the transitional period during the Mid-Pleistocene (55–68 mbsf), a slow moving inland ice sheet deposited tills with brittle deformation, producing lineations and bi-masepic and unistrial plasma fabric, along with high relief, conchoidally fractured quartz grains. Changes in the provenance of gravel to cobble-size clasts support a distant source area of Byrd Glacier for fast-flowing paleo-ice streams and a proximal area between Darwin and Skelton Glaciers for the slow-moving inland ice sheet. This difference in till provenance documents a shift in direction of glacial flow at the core site, which indirectly reflects changes in the size and thickness of the WAIS. Hence, we found that fast ice streaming motion is a consequence of a thicker WAIS pushing flow lines to the west and introducing clasts from the Byrd Glacier source area to the drill site. The detailed analysis of diamictites inAND-1B demonstrates that Pliocene glacial ... Other/Unknown Material Antarc* Antarctic Byrd Glacier glacier Greenland Ice Sheet Ice Shelf McMurdo Sound Ross Ice Shelf University of North Carolina: NC DOCKS (Digital Online Collection of Knowledge and Scholarship) Antarctic Byrd Byrd Glacier ENVELOPE(160.333,160.333,-80.250,-80.250) Greenland McMurdo Sound Ross Ice Shelf The Antarctic West Antarctic Ice Sheet |
institution |
Open Polar |
collection |
University of North Carolina: NC DOCKS (Digital Online Collection of Knowledge and Scholarship) |
op_collection_id |
ftunivnorthcag |
language |
English |
description |
Geologic studies of sediment deposited by glaciers can provide crucial insights into the subglacial environment. We studied muddy diamictites in the ANtarctic geological DRILLing (ANDRILL) AND-1B drill core, acquired from beneath the Ross Ice Shelf in McMurdo Sound, with the aim of identifying paleo-ice stream activity in the Plio– Pleistocene. Glacial advances were identified from glacial surfaces of erosion (GSEs) and subglacial diamictites within three complete sequences were investigated using lithofacies associations, micromorphology, and quartz sand grain microtextures. Whereas conditions in the Late Pliocene resemble the modern Greenland Ice Sheet where fast flowing glaciers lubricated by surface meltwater terminate directly in the sea (interval 201–212 mbsl) conditions in the Late Pleistocene are similar to modern West Antarctic Ice Sheet (WAIS) ice streams (38–49 mbsl). We identify the latter from ductile deformation and high pore-water pressure, which resulted in pervasive rotation and formation of till pellets and low relief, rounded sand grains dominated by abrasion. In the transitional period during the Mid-Pleistocene (55–68 mbsf), a slow moving inland ice sheet deposited tills with brittle deformation, producing lineations and bi-masepic and unistrial plasma fabric, along with high relief, conchoidally fractured quartz grains. Changes in the provenance of gravel to cobble-size clasts support a distant source area of Byrd Glacier for fast-flowing paleo-ice streams and a proximal area between Darwin and Skelton Glaciers for the slow-moving inland ice sheet. This difference in till provenance documents a shift in direction of glacial flow at the core site, which indirectly reflects changes in the size and thickness of the WAIS. Hence, we found that fast ice streaming motion is a consequence of a thicker WAIS pushing flow lines to the west and introducing clasts from the Byrd Glacier source area to the drill site. The detailed analysis of diamictites inAND-1B demonstrates that Pliocene glacial ... |
author |
Cowan, Ellen A. NC DOCKS at Appalachian State University |
spellingShingle |
Cowan, Ellen A. NC DOCKS at Appalachian State University Dynamics Of The Late Plio-Pleistocene West Antarctic Ice Sheet Documented In Subglacial Diamictites, AND-1B Drill Core |
author_facet |
Cowan, Ellen A. NC DOCKS at Appalachian State University |
author_sort |
Cowan, Ellen A. |
title |
Dynamics Of The Late Plio-Pleistocene West Antarctic Ice Sheet Documented In Subglacial Diamictites, AND-1B Drill Core |
title_short |
Dynamics Of The Late Plio-Pleistocene West Antarctic Ice Sheet Documented In Subglacial Diamictites, AND-1B Drill Core |
title_full |
Dynamics Of The Late Plio-Pleistocene West Antarctic Ice Sheet Documented In Subglacial Diamictites, AND-1B Drill Core |
title_fullStr |
Dynamics Of The Late Plio-Pleistocene West Antarctic Ice Sheet Documented In Subglacial Diamictites, AND-1B Drill Core |
title_full_unstemmed |
Dynamics Of The Late Plio-Pleistocene West Antarctic Ice Sheet Documented In Subglacial Diamictites, AND-1B Drill Core |
title_sort |
dynamics of the late plio-pleistocene west antarctic ice sheet documented in subglacial diamictites, and-1b drill core |
publishDate |
2014 |
url |
http://libres.uncg.edu/ir/asu/f/Cowan_Ellen_2014_RECAPP_Dynamics of the late Plio.pdf |
long_lat |
ENVELOPE(160.333,160.333,-80.250,-80.250) |
geographic |
Antarctic Byrd Byrd Glacier Greenland McMurdo Sound Ross Ice Shelf The Antarctic West Antarctic Ice Sheet |
geographic_facet |
Antarctic Byrd Byrd Glacier Greenland McMurdo Sound Ross Ice Shelf The Antarctic West Antarctic Ice Sheet |
genre |
Antarc* Antarctic Byrd Glacier glacier Greenland Ice Sheet Ice Shelf McMurdo Sound Ross Ice Shelf |
genre_facet |
Antarc* Antarctic Byrd Glacier glacier Greenland Ice Sheet Ice Shelf McMurdo Sound Ross Ice Shelf |
op_relation |
http://libres.uncg.edu/ir/asu/f/Cowan_Ellen_2014_RECAPP_Dynamics of the late Plio.pdf |
_version_ |
1811632941824999424 |