Sedimentation beneath ice shelves — the view from ice stream B

Alley, Richard B.; Blankenship, D. D.; Rooney, S. T.; Bentley, C. R.

doi:10.1016/0025-3227(89)90150-3

Cited by 328 publications

(250 citation statements)

References 79 publications

Supporting

Mentioning

239

Contrasting

Unclassified

Order By: Relevance

“…S3). The features possess morphological traits of grounding zone wedges (GZWs), including steep downstream-facing ramps, shallow back-slopes, and lineations terminating at wedge crests (Alley et al, 1989;Vanneste and Larter, 1995;Howat and Domack, 2003;Ó Cofaigh et al, 2005b;Evans et al, 2005aEvans et al, , 2006Anandakrishnan et al, 2007;Ottesen et al, 2008). The GZW crests rise up to 100-120 m above the surrounding sea floor, are 4 km wide, and extend over 5-10 km.…”

Section: Inner To Middle Shelfmentioning

confidence: 99%

“…large moraines or GZWs; see O'Brien et al, 1999;Shipp et al, 1999). In an ice stream deforming bed system operating as a sediment conveyer, till accumulation would be expected at the terminal position of the ice stream (Alley et al, 1989). An absence of such accumulations on the outer shelf in the western ASE suggests that the grounding line probably advanced to the shelf break during the LGM, and subsequently retreated rapidly or continuously across the outer shelf .…”

Section: Reconstruction Of Palaeo-ice Stream Flowmentioning

confidence: 99%

See 1 more Smart Citation

Bedform signature of a West Antarctic palaeo-ice stream reveals a multi-temporal record of flow and substrate control

Graham

Larter

Gohl

et al. 2009

Quaternary Science Reviews

175

173

View full text Add to dashboard Cite

a b s t r a c tThe presence of a complex bedform arrangement on the sea floor of the continental shelf in the western Amundsen Sea Embayment, West Antarctica, indicates a multi-temporal record of flow related to the activity of one or more ice streams in the past. Mapping and division of the bedforms into distinct landform assemblages reveals their time-transgressive history, which implies that bedforms can neither be considered part of a single downflow continuum nor a direct proxy for palaeo-ice velocity, as suggested previously. A main control on the bedform imprint is the geology of the shelf, which is divided broadly between rough bedrock on the inner shelf, and smooth, dipping sedimentary strata on the middle to outer shelf. Inner shelf bedform variability is well preserved, revealing information about local, complex basal ice conditions, meltwater flow, and ice dynamics over time. These details, which are not apparent at the scale of regional morphological studies, indicate that past ice streams flowed across the entire shelf at times, and often had onset zones that lay within the interior of the Antarctic Ice Sheet today. In contrast, highly elongated subglacial bedforms on sedimentary strata of the middle to outer shelf represent a timeslice snapshot of the last activity of ice stream flow, and may be a truer representation of fast palaeo-ice flow in these locations. A revised model for ice streams on the shelf captures complicated multi-temporal bedform patterns associated with an Antarctic palaeo-ice stream for the first time, and confirms a strong substrate control on a major ice stream system that drained the West Antarctic Ice Sheet during the Late Quaternary.

show abstract

Section: Inner To Middle Shelfmentioning

confidence: 99%

Section: Reconstruction Of Palaeo-ice Stream Flowmentioning

confidence: 99%

Bedform signature of a West Antarctic palaeo-ice stream reveals a multi-temporal record of flow and substrate control

Graham

Larter

Gohl

et al. 2009

Quaternary Science Reviews

175

173

View full text Add to dashboard Cite

show abstract

“…While the build-up of the slope-prograding glacial strata is generally attributed to sustained, but relatively small-scale debris-£ow activity from the ice-sheet grounding line during glacial periods (e.g. Alley et al, 1989;Aksu and Hiscott, 1992;Vorren, 1995, 2000b), the larger-scale, more catastrophic failure of these glacial strata is usually believed to occur in a later phase, after deglaciation and during the interglacial periods (Bugge et al, 1987;Bart et al, 1999;Laberg and Vorren, 2000a). Based on analyses of maximum ice-loading events for the Scotian slope, Mulder and Moran (1995) suggest that the change in ice loading (e.g.…”

Section: Twt (Ms) Twt (Ms) Twt (Ms) Twt (Ms)mentioning

confidence: 99%

The Gebra Slide: a submarine slide on the Trinity Peninsula Margin, Antarctica

et al. 2003

View full text Add to dashboard Cite

A large submarine slide^the Gebra Slide^has been discovered on the continental margin of Trinity Peninsula, Central Bransfield Basin, Antarctic Peninsula. The slide scar is clearly expressed in the bathymetry and is cut into the toe of the glacial-period slope-prograding strata on the lower continental slope. Seismic data give evidence of an associated debris-flow deposit embedded in the interglacial-period basin-fill strata of the basin floor. The total volume of sediment involved in the mass movement is about 20 km 3 . Indirect dating of the mass-wasting event, based on seismic^stratigraphic relationships of the slide scar and associated debris-flow deposit with underlying glacial-period slope units and the overlying interglacial-period basin-floor units, suggests that it took place at the transition between the last glacial period and the present-day interglacial. The initiation of the Gebra Slide is attributed to a combination of several factors, such as high sedimentation rates during the last glacial period, the unloading effect of a retreating ice sheet during deglaciation, pre-existing tectonic fabric and high seismicity in the area. This is the first recent submarine slide of this size identified on the glacial, continental margins of Antarctica. In morphology and general characteristics it is quite similar to the well-known large-scale submarine slides from the northern hemisphere glacial margins, although it is smaller. Its most striking characteristic is its lower-slope position (at 1500^2000 m of water depth), which remains up to now difficult to explain. ß

show abstract

“…7). GZW are depositional features, formed during stillstand periods during a general ice retreat, when sediment is carried to the grounding line through bed deformation and basal melting (Alley et al, 1989;Anderson, 1999;Dowdeswell et al, 2008;Batchelor and Dowdeswell, 2015). Most of the GZW observed in the western AP bays are asymmetric, with a steep slope distal and gentler slope proximal to the ice front (Figs.…”

Section: Ice-marginal Landforms Large Transverse Ridges: Grounding Zomentioning

confidence: 99%

Seafloor geomorphology of western Antarctic Peninsula bays: a signature of ice flow behaviour

Munoz

Wellner

2018

The Cryosphere

View full text Add to dashboard Cite

Abstract. Glacial geomorphology is used in Antarctica to reconstruct ice advance during the Last Glacial Maximum and subsequent retreat across the continental shelf. Analogous geomorphic assemblages are found in glaciated fjords and are used to interpret the glacial history and glacial dynamics in those areas. In addition, understanding the distribution of submarine landforms in bays and the local controls exerted on ice flow can help improve numerical models by providing constraints through these drainage areas. We present multibeam swath bathymetry from several bays in the South Shetland Islands and the western Antarctic Peninsula. The submarine landforms are described and interpreted in detail. A schematic model was developed showing the features found in the bays: from glacial lineations and moraines in the inner bay to grounding zone wedges and drumlinoid features in the middle bay and streamlined features and meltwater channels in the outer bay areas. In addition, we analysed local variables in the bays and observed the following: (1) the number of landforms found in the bays scales to the size of the bay, but the geometry of the bays dictates the types of features that form; specifically, we observe a correlation between the bay width and the number of transverse features present in the bays. (2) The smaller seafloor features are present only in the smaller glacial systems, indicating that short-lived atmospheric and oceanographic fluctuations, responsible for the formation of these landforms, are only recorded in these smaller systems. (3) Meltwater channels are abundant on the seafloor, but some are subglacial, carved in bedrock, and some are modern erosional features, carved on soft sediment. Lastly, based on geomorphological evidence, we propose the features found in some of the proximal bay areas were formed during a recent glacial advance, likely the Little Ice Age.

show abstract

Sedimentation beneath ice shelves — the view from ice stream B

Cited by 328 publications

References 79 publications

Bedform signature of a West Antarctic palaeo-ice stream reveals a multi-temporal record of flow and substrate control

Bedform signature of a West Antarctic palaeo-ice stream reveals a multi-temporal record of flow and substrate control

The Gebra Slide: a submarine slide on the Trinity Peninsula Margin, Antarctica

Seafloor geomorphology of western Antarctic Peninsula bays: a signature of ice flow behaviour

Contact Info

Product

Resources

About