Dating Holocene ice-sheet advance in West Antarctica using englacial radio-stratigraphy and sea-level records (Invited)
Abstract
In the Weddell and Ross Sea sectors of West Antarctica, ice-sheet reconstructions have assumed progressive grounding line retreat during the Holocene. However, there is growing evidence for more complexity. For example, recent work (Kingslake, Scherer, Albrecht et al., 2018) presented evidence for Holocene ice-sheet expansion in these sectors. Radiocarbon dating of subglacial sediments recovered from the Ross Sea Sector indicated Holocene marine exposure 100's of km upstream of today's grounding line and ice-penetrating radar observations in the Weddell Sea Sector indicated ice-shelf grounding. Ice-sheet modelling suggested that post-LGM glacial isostatic uplift (GIA) caused the grounding line re-advance.
We report here on two complimentary efforts to date these events. The first method is focused in the Weddell Sea and uses englacial radiostratigraphy from the Henry Ice Rise. Using the depth of relic basal crevasses and a simple ice-flow model, we estimate the time taken for the crevasses to be buried. Taking into account uncertainty in accumulation, firn density, radar-derived depth, ice-thickening history, initial crevasse height, and GIA, we estimate a burial time of 4 ± 2 kyr before present for the oldest relic crevasses, indicating that the ice rise formed around this time. The second method uses the output of an ensemble of ice-sheet model simulations of Holocene retreat and readvance with a global sea level model that accounts for GIA, to determine the sea-level signal of West-Antarctic re-advance. This information can potentially be used to date re-advance by interrogating Holocene sea-level records from locations where sea level is most sensitive to this re-advance. To build detailed chronologies of Holocene re-advance in West Antarctica, these approaches must be refined and applied more widely. Moreover, applying them in conjunction with drilling to areas of the bed which may have been sub-marine (for radiocarbon analysis) or sub-areal (for cosmogenic exposure dating), could provide strong new constraints on ice-sheet and sea-level models.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFMPP11A..08K
- Keywords:
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- 0726 Ice sheets;
- CRYOSPHEREDE: 1641 Sea level change;
- GLOBAL CHANGEDE: 4926 Glacial;
- PALEOCEANOGRAPHYDE: 4936 Interglacial;
- PALEOCEANOGRAPHY