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Thickness of the divide and flank of the West Antarctic Ice Sheet through the last deglaciation


Title (Dublin Core)

Thickness of the divide and flank of the West Antarctic Ice Sheet through the last deglaciation

Description (Dublin Core)

<p>We report cosmogenic-nuclide measurements from two isolated groups of nunataks in West Antarctica: the Pirrit Hills, located midway between the grounding line and the divide in the Weddell Sea sector, and the Whitmore Mountains, located along the Ross–Weddell divide. At the Pirrit Hills, evidence of glacial-stage ice cover extends <span class="inline-formula">∼320</span>&thinsp;m above the present ice surface. Subsequent thinning mostly occurred after <span class="inline-formula">∼14</span>&thinsp;kyr&thinsp;BP, and modern ice levels were established some time after <span class="inline-formula">∼4</span>&thinsp;kyr&thinsp;BP. We infer that, like at other flank sites, these changes were primarily controlled by the position of the grounding line downstream. At the Whitmore Mountains, cosmogenic <span class="inline-formula"><sup>14</sup>C</span> concentrations in bedrock surfaces demonstrate that ice there was no more than <span class="inline-formula">∼190</span>&thinsp;m thicker than present during the past <span class="inline-formula">∼30</span>&thinsp;kyr. Combined with other constraints from West Antarctica, the <span class="inline-formula"><sup>14</sup>C</span> data imply that the divide was thicker than present for a period of less than <span class="inline-formula">∼8</span>&thinsp;kyr within the past <span class="inline-formula">∼15</span>&thinsp;kyr. These results are consistent with the hypothesis that the divide initially thickened due to the deglacial rise in snowfall and subsequently thinned in response to retreat of the ice-sheet margin. We use these data to evaluate several recently published ice-sheet models at the Pirrit Hills and Whitmore Mountains. Most of the models we consider do not match the observed timing and/or magnitude of thickness change at these sites. However, one model performs relatively well at both sites, which may, in part, be due to the fact that it was calibrated with geological observations of ice-thickness change from other sites in Antarctica.</p>

Creator (Dublin Core)

P. Spector
J. Stone
B. Goehring

Subject (Dublin Core)

Environmental sciences

Publisher (Dublin Core)

Copernicus Publications

Date (Dublin Core)


Type (Dublin Core)


Identifier (Dublin Core)


Source (Dublin Core)

The Cryosphere, Vol 13, Pp 3061-3075 (2019)

Language (Dublin Core)


Relation (Dublin Core)

Provenance (Dublin Core)

Journal Licence: CC BY