Seafloor evidence of a subglacial sedimentary system off the northern Antarctic Peninsula

Canals, Miquel; Casamor, J. L.; Úrgeles, Roger; Calafat, Antoni; Domack, Eugene W.; Baraza, J.; Farran, Marcel-lí; Batist, Marc De

doi:10.1130/0091-7613(2002)030<0603:seoass>2.0.co;2

Cited by 85 publications

(71 citation statements)

References 13 publications

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“…According to Pudsey et al (1994), open marine sedimentation started shortly before 11000 yr BP on the outer shelf o¡ Anvers Island, to the southwest of the Brans¢eld Basin. The shallower and largely sediment-free inner shelf cleared much later, perhaps around 6000 yr BP (Canals et al, 2002). On our seismic data, the most recent seismic^stratigraphic interglacial unit U8 is essentially developed on the King George basin £oor (over 100 m of thickness), but it also extends, although much thinner (only about 7 m), on the slope and outer shelf of the Trinity Peninsula Margin (Figs.…”

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

confidence: 73%

“…1 and 2). The inner continental shelf is up to 250 m deep and incised by four large glacial troughs (Szeliga, 1990;Canals et al, 2002). Some shallower incisions can be recognized further to the NE, facing the Antarctic Sound, but their small dimensions suggest that they played only a minor role in the glacial drainage process and as a sediment pathway to the outer shelf.…”

Section: Geological Setting and Physiographymentioning

confidence: 99%

“…The Gebra Slide is located at the transition between two distinct morphostructural segments of the Trinity Peninsula Margin, and in between two of the basinward-convex lobes that mark the shelf edge ( Fig. 3) (Prieto et al, 1999;Canals et al, 2002). To the northeast of the Gebra Slide the margin consists of a gentle, uniform slope with a mean gradient of about 1 ‡ and underlain by an up to 600 m thick sedimentary sequence (Fig.…”

Section: The Gebra Slidementioning

confidence: 99%

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

et al. 2003

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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

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

confidence: 73%

Section: Geological Setting and Physiographymentioning

confidence: 99%

Section: The Gebra Slidementioning

confidence: 99%

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

et al. 2003

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“…Numerous landform models have argued that the bedrock-sediment substrate boundary controls the onset of ice stream flow (e.g. Shipp et al, 1999Shipp et al, , 2002Wellner et al, 2001;Canals et al, 2002;Evans et al, 2006;Ottesen et al, 2008), but this appears not to be the case in the western ASE. While we find evidence for flow acceleration in the convergent pattern of bedforms, the onset of past ice streaming was clearly located, at times, much further south of the substrate boundary and likely beneath the ice sheet today.…”

Section: Multi-temporal Record Of Flow and Substrate Controls On Bedfmentioning

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

174

173

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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.

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“…They speculate that mounds at B700 m depth mark the maximum advance during the LGM. Deep troughs with mega-scale lineations are incised into the shelf and are interpreted as the paths of palaeo-ice streams (Banfield and Anderson, 1995;Canals et al, 2002).…”

Section: The South Shetland Islands Regionmentioning

confidence: 99%