Evidence for a palaeo-subglacial lake on the Antarctic continental shelf

Kuhn, Gerhard; Hillenbrand, Claus‐Dieter; Kasten, Sabine; Smith, James A; Nitsche, F. O.; Frederichs, Thomas; Wiers, Steffen; Ehrmann, Werner; Klages, Johann Philipp; Mogollón, José M

doi:10.1038/ncomms15591

Cited by 64 publications

(54 citation statements)

References 53 publications

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“…Lake (i) occurs at the confluence of the main streams that drain the Pine Island and Thwaites glacier catchments; lake (ii) is the furthest downstream lake in the Thwaites catchment, and lake (iii) is the furthest downstream lake in the Pine Island catchment. The fourth example lake occurs within the relict subglacial lake basin described by Kuhn et al (2017). The four example lakes have volumes between 0.33 and 19.9 km 3 when filled to their spill points.…”

Section: Modelled Subglacial Hydrologymentioning

confidence: 99%

“…Under these continuous flow rates, the three lakes would fill to their spill points on annual to decadal timescales ( Table 2). The basin described by Kuhn et al (2017) is smaller than the lakes draining the main glacier catchments and is modelled to accumulate water at a steady-state rate of 0.23 m 3 s −1 , filling to its spill point every 45 years. If these example lakes were to drain over a ∼ 16-month period, typical of subglacial water transfer beneath the contemporary Antarctic Ice Sheet (Wingham et al, 2006), water would be released from the lakes at an average rate of ∼ 10-80 m 3 s −1 for the three smaller lakes (i, ii, iv) and ∼ 470 m 3 s −1 for lake (iii) at the edge of the individual Pine Island glacier catchment (Table 2).…”

Section: Modelled Subglacial Hydrologymentioning

confidence: 99%

“…b Potential mean flood discharge calculated by assuming drainage of a large upstream lake in 16 months (see Wingham et al, 2006), which triggers the cascading drainage of all lakes downstream from that initial event. c Basin suggested to be a relict subglacial lake by Kuhn et al (2017). icant sediment infill of the base of the channel is present (e.g.…”

Section: Channel Formationmentioning

confidence: 99%

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Past water flow beneath Pine Island and Thwaites glaciers, West Antarctica

et al. 2019

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Outburst floods from subglacial lakes beneath the Antarctic Ice Sheet modulate ice-flow velocities over periods of months to years. Although subglacial lake drainage events have been observed from satellite-altimetric data, little is known about their role in the long-term evolution of ice-sheet basal hydrology. Here, we systematically map and model past water flow through an extensive area containing over 1000 subglacial channels and 19 former lake basins exposed on over 19 000 km 2 of seafloor by the retreat of Pine Island and Thwaites glaciers, West Antarctica. At 507 m wide and 43 m deep on average, the channels offshore of presentday Pine Island and Thwaites glaciers are approximately twice as deep, 3 times as wide, and cover an area over 400 times larger than the terrestrial meltwater channels comprising the Labyrinth in the Antarctic Dry Valleys. The channels incised into bedrock offshore of contemporary Pine Island and Thwaites glaciers would have been capable of accommodating discharges of up to 8.8 × 10 6 m 3 s −1 . We suggest that the channels were formed by episodic discharges from subglacial lakes trapped during ice-sheet advance and retreat over multiple glacial periods. Our results document the widespread influence of episodic subglacial drainage events during past glacial periods, in particular beneath large ice streams similar to those that continue to dominate contemporary ice-sheet discharge.

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Section: Modelled Subglacial Hydrologymentioning

confidence: 99%

Section: Modelled Subglacial Hydrologymentioning

confidence: 99%

Section: Channel Formationmentioning

confidence: 99%

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Past water flow beneath Pine Island and Thwaites glaciers, West Antarctica

et al. 2019

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“…The aim was to select potential drill sites for three major objectives: (1) Obtain samples from small sedimentary basins that are nested on the outcropping crystalline basement of the inner shelf. Inner shelf sites may contain high‐resolution records of the Quaternary WAIS dynamics and its forcing (Hillenbrand et al, ; Smith et al, ), with some inner shelf basins containing deposits of former subglacial lakes (Kuhn et al, ). (2) Drill through postglacial deposits and a thin cover of last glacial till to collect drill cores from older strata that dip oceanward and are truncated close to the seafloor on the middle shelf.…”

Section: Drill Operationsmentioning

confidence: 99%

Section: Site Selectionmentioning

confidence: 99%

MeBo70 Seabed Drilling on a Polar Continental Shelf: Operational Report and Lessons From Drilling in the Amundsen Sea Embayment of West Antarctica

Gohl

Freudenthal

Hillenbrand

et al. 2017

Geochem Geophys Geosyst

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A multibarrel seabed drill rig was used for the first time to drill unconsolidated sediments and consolidated sedimentary rocks from an Antarctic shelf with core recoveries between 7% and 76%. We deployed the MARUM‐MeBo70 drill device at nine drill sites in the Amundsen Sea Embayment. Three sites were located on the inner shelf of Pine Island Bay from which soft sediments, presumably deposited at high sedimentation rates in isolated small basins, were recovered from drill depths of up to 36 m below seafloor. Six sites were located on the middle shelf of the eastern and western embayment. Drilling at five of these sites recovered consolidated sediments and sedimentary rocks from dipping strata spanning ages from Cretaceous to Miocene. This report describes the initial coring results, the challenges posed by drifting icebergs and sea ice, and technical issues related to deployment of the MeBo70. We also present recommendations for similar future drilling campaigns on polar continental shelves.

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Subglacial evolution from distributed to channelized drainage: Evidence from the Lake Murtoo area in SW Finland

Ojala

Mäkinen

Kajuutti

et al. 2022

Earth Surf Processes Landf

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During the last millennia of the Weichselian glaciation (c. 11 700-14 000 cal BP) and the first millennium of the Holocene interglacial (c. 10 500-11 700 cal BP), melting of the ice sheet and subsequent subglacial drainage resulted in the formation of murtoos and murtoo-related landforms in the Fennoscandian Ice Sheet area in Finland and Sweden. Murtoos are composed of clay-poor diamictons produced by sediment-concentrated creep and material sorting in a subglacial environment under effective pressure close to zero, and potentially represent a transition form from non-channelized to channelized subglacial drainage networks. Here, we explore the geomorphology and substratum characteristics of the Lake Murtoo area, one of the locations where murtoos were initially found and described in SW Finland. Our interpretation suggests an interconnected development from inefficient distributed or semi-distributed cavities (murtoos) to efficient channelized drainage (esker) via erosional escarpments, all displayed in the same region. In addition, our excavation into a murtoo-related erosional escarpment (MRE) revealed subglacial erosional channels alongside MREs that were filled with fine-grained finely laminated sediments. We suggest that these channel fill sediments were deposited subglacially, because they are covered by flow till and show spatial and lithological characteristics that deviate significantly from the proglacial basin fill clay (varve) sediments in the area. The appearance of rhythmically laminated silt and clay sediments indicates sedimentation in a suspension-load-dominated environment in shallow subglacial channels with relatively low (but repetitiously changing) water flow velocities, possibly reflecting disconnected spill-over routes of subglacial drainage in small tributaries that were only periodically used due to water pressure changes in the up-ice direction.

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Evidence for a palaeo-subglacial lake on the Antarctic continental shelf

Cited by 64 publications

References 53 publications

Past water flow beneath Pine Island and Thwaites glaciers, West Antarctica

Past water flow beneath Pine Island and Thwaites glaciers, West Antarctica

MeBo70 Seabed Drilling on a Polar Continental Shelf: Operational Report and Lessons From Drilling in the Amundsen Sea Embayment of West Antarctica

Subglacial evolution from distributed to channelized drainage: Evidence from the Lake Murtoo area in SW Finland

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