Submarine glacial landforms and rates of ice-stream collapse

Dowdeswell, Julian A.; Ottesen, Dag; Evans, Jeffrey; Cofaigh, Colm Ó; Anderson, John B.

doi:10.1130/g24808a.1

Cited by 219 publications

(207 citation statements)

References 21 publications

Supporting

Mentioning

199

Contrasting

Order By: Relevance

“…Thus, our observation of hill-hole pairs superimposing MSGLs may imply that slow flow and cold-based conditions characterised the final phase of glacial activity in this area. This scenario contrasts with the hypothesis of accelerated flow during post-LGM ice sheet retreat from other parts of the West Antarctic continental shelf (e.g., Mosola and Anderson, 2006;Dowdeswell et al, 2008).…”

Section: Evidence For Past Changes In Basal Conditionscontrasting

confidence: 46%

Palaeo-ice stream pathways and retreat style in the easternmost Amundsen Sea Embayment, West Antarctica, revealed by combined multibeam bathymetric and seismic data

et al. 2015

View full text Add to dashboard Cite

Multibeam swath bathymetry data sets collected over the past two decades have been compiled to identify palaeo-ice stream pathways in the easternmost Amundsen Sea Embayment. We mapped~3000 glacial landforms to reconstruct ice flow in the~250-km-long cross-shelf Abbot Trough. This bathymetric feature was occupied by a large ice stream, which was fed by two tributaries (Cosgrove and Abbot) and reached the continental shelf edge during the last maximum ice sheet advance. Geomorphological mapping has enabled a clear differentiation between subglacial landforms indicating warm-(e.g., megascale glacial lineations) and cold-based (e.g., hill-hole pairs) ice conditions on the continental shelf during the last glaciation. Grounding-zone wedges and recessional moraines, mapped within the palaeo-ice stream troughs and on adjacent sea-floor highs (referred to as inter-ice stream ridges) indicate grounding line stillstands or re-advances of the West Antarctic Ice Sheet during the last deglaciation of the shelf. We observe that the locations of grounding-zone wedges coincide with trough constrictions as well as local topographic highs of harder substrate. This combination of trough 'bottlenecks' and local pinning points on an otherwise retrograde slope is likely to have modified the pace of grounding-line retreat, causing the grounding zone to pause and deposit grounding-zone wedges. The episodic retreat recorded within Abbot Trough corresponds to post-glacial episodic retreat interpreted for the neighbouring Pine Island-Thwaites palaeo-ice stream trough, thus suggesting a uniform pattern of retreat across the eastern Amundsen Sea Embayment. Locally, indications are strong that a change in basal thermal regime of the ice from warm-to cold-based conditions occurred prior to final retreat, as hill-hole pairs overprint megascale glacial lineations. Further, the correlation of grounding-zone wedges with geological boundaries emphasises the influence of subglacial geology on ice stream flow. Our new geomorphological map of the easternmost Amundsen Sea Embayment resolves the pathways of palaeo-ice streams that were probably all active during the last maximum extent of the ice sheet, and the extent of adjacent inter-ice stream ridges. It reveals information about the style of, and the basal thermal regime during, the subsequent grounding line retreat. Such information provides an important empirical framework by which the accuracy of ice sheet models can be gauged.

show abstract

Section: Evidence For Past Changes In Basal Conditionscontrasting

confidence: 46%

Palaeo-ice stream pathways and retreat style in the easternmost Amundsen Sea Embayment, West Antarctica, revealed by combined multibeam bathymetric and seismic data

et al. 2015

View full text Add to dashboard Cite

show abstract

“…The arrows indicate corrected 14 C ages of global meltwater pulses (Fairbanks, 1989;Clark et al, 2002Clark et al, , 2004. observed in Belgica Trough by Ó Cofaigh et al (2005b), which indicate that the ice-stream retreat was episodic (Dowdeswell et al, 2008b;Ó Cofaigh et al, 2008). Thus, it is conceivable that there may have been considerable variations in retreat rates between grounding-line positions.…”

Section: History Of Ice-sheet Retreatmentioning

confidence: 99%

“…Bindschadler, 1998;Conway et al, 1999;Pudsey and Evans, 2001;Stone et al, 2003;Alley et al, 2005;Domack et al, 2005;Anderson, 2005, 2007;Bentley et al, 2006Bentley et al, , 2009Dowdeswell et al, 2008b;Johnson et al, 2008). Similarly, it is unclear if Antarctic deglaciation since the last glacial period has contributed to prominent global meltwater pulses (Clark et al, 2002;Licht, 2004;Peltier, 2005;Bassett et al, 2007).…”

Section: Motivationmentioning

confidence: 99%

The sedimentary legacy of a palaeo-ice stream on the shelf of the southern Bellingshausen Sea: Clues to West Antarctic glacial history during the Late Quaternary

Hillenbrand

Larter

Dowdeswell

et al. 2010

Quaternary Science Reviews

Self Cite

View full text Add to dashboard Cite

a b s t r a c tA major trough ("Belgica Trough") eroded by a palaeo-ice stream crosses the continental shelf of the southern Bellingshausen Sea (West Antarctica) and is associated with a trough mouth fan ("Belgica TMF") on the adjacent continental slope. Previous marine geophysical and geological studies investigated the bathymetry and geomorphology of Belgica Trough and Belgica TMF, erosional and depositional processes associated with bedform formation, and the temporal and spatial changes in clay mineral provenance of subglacial and glaciomarine sediments.Here, we present multi-proxy data from sediment cores recovered from the shelf and uppermost slope in the southern Bellingshausen Sea and reconstruct the ice-sheet history since the last glacial maximum (LGM) in this poorly studied area of West Antarctica. We combined new data (physical properties, sedimentary structures, geochemical and grain-size data) with published data (shear strength, clay mineral assemblages) to refine a previous facies classification for the sediments. The multi-proxy approach allowed us to distinguish four main facies types and to assign them to the following depositional settings: 1) subglacial, 2) proximal grounding-line, 3) distal sub-ice shelf/sub-sea ice, and 4) seasonal open-marine. In the seasonal open-marine facies we found evidence for episodic currentinduced winnowing of near-seabed sediments on the middle to outer shelf and at the uppermost slope during the late Holocene.In addition, we obtained data on excess 210 Pb activity at three core sites and 44 AMS 14 C dates from the acid-insoluble fraction of organic matter (AIO) and calcareous (micro-) fossils, respectively, at 12 sites. These chronological data enabled us to reconstruct, for the first time, the timing of the last advance and retreat of the West Antarctic Ice Sheet (WAIS) and the Antarctic Peninsula Ice Sheet (APIS) in the southern Bellingshausen Sea. We used the down-core variability in sediment provenance inferred from clay mineral changes to identify the most reliable AIO 14 C ages for ice-sheet retreat. The palaeo-ice stream advanced through Belgica Trough after w36.0 corrected 14 C ka before present (B.P.). It retreated from the outer shelf at w25.5 ka B.P., the middle shelf at w19.8 ka B.P., the inner shelf in Eltanin Bay at w12.3 ka B.P., and the inner shelf in Ronne Entrance at w6.3 ka B.P. The retreat of the WAIS and APIS occurred slowly and stepwise, and may still be in progress. This dynamical ice-sheet behaviour has to be taken into account for the interpretation of recent and the prediction of future mass-balance changes in the study area. The glacial history of the southern Bellingshausen Sea is unique when compared to other regions in West Antarctica, but some open questions regarding its chronology need to be addressed by future work.

show abstract

“…High-latitude glaciated continental shelves in both the Arctic and Antarctica are characterized by relatively deep cross-shelf troughs, separated by intervening shallow banks, that extend from the mouths of fjords draining the hinterland of adjacent landmasses (figure 2) [3,38,39]. The record of glacial landforms and sediments preserved across these shelves and, in particular, within the cross-shelf troughs has enabled the reconstruction of former ice sheets in terms of their extent, flow dynamics and nature of their retreat [4,[40][41][42][43][44]. A major development has been the recognition that these shelf troughs acted as the loci for fast-flowing ice streams during glacial maxima.…”

Section: (B) Reconstruction Of Past Ice Sheets On High-and Mid-latitumentioning

confidence: 99%

Ice sheets viewed from the ocean: the contribution of marine science to understanding modern and past ice sheets

Cofaigh

2012

Phil. Trans. R. Soc. A.

View full text Add to dashboard Cite

Over the last two decades, marine science, aided by technological advances in sediment coring, geophysical imaging and remotely operated submersibles, has played a major role in the investigation of contemporary and former ice sheets. Notable advances have been achieved with respect to reconstructing the extent and flow dynamics of the large polar ice sheets and their mid-latitude counterparts during the Quaternary from marine geophysical and geological records of landforms and sediments on glacierinfluenced continental margins. Investigations of the deep-sea ice-rafted debris record have demonstrated that catastrophic collapse of large (10 5 -10 6 km 2 ) ice-sheet drainage basins occurred on millennial and shorter time scales and had a major influence on oceanography. In the last few years, increasing emphasis has been placed on understanding physical processes at the ice-ocean interface, particularly at the grounding line, and on determining how these processes affect ice-sheet stability. This remains a major challenge, however, owing to the logistical constraints imposed by working in ice-infested polar waters and ice-shelf cavities. Furthermore, despite advances in reconstructing the Quaternary history of mid-and high-latitude ice sheets, major unanswered questions remain regarding West Antarctic ice-sheet stability, and the longterm offshore history of the East Antarctic and Greenland ice sheets remains poorly constrained. While these are major research frontiers in glaciology, and ones in which marine science has a pivotal role to play, realizing such future advances will require an integrated collaborative approach between oceanographers, glaciologists, marine geologists and numerical modellers.

show abstract

Submarine glacial landforms and rates of ice-stream collapse

Cited by 219 publications

References 21 publications

Palaeo-ice stream pathways and retreat style in the easternmost Amundsen Sea Embayment, West Antarctica, revealed by combined multibeam bathymetric and seismic data

Palaeo-ice stream pathways and retreat style in the easternmost Amundsen Sea Embayment, West Antarctica, revealed by combined multibeam bathymetric and seismic data

The sedimentary legacy of a palaeo-ice stream on the shelf of the southern Bellingshausen Sea: Clues to West Antarctic glacial history during the Late Quaternary

Ice sheets viewed from the ocean: the contribution of marine science to understanding modern and past ice sheets

Contact Info

Product

Resources

About