Large subglacial lake beneath the Laurentide Ice Sheet inferred from sedimentary sequences

Christoffersen, Poul; Tulaczyk, S. M.; Wattrus, N. J.; Peterson, Justin; Krupinski, N. Quintana; Clark, Chris D.; Sjunneskog, Charlotte

doi:10.1130/g24628a.1

Cited by 41 publications

(30 citation statements)

References 34 publications

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“…McCabe and Ó Cofaigh, 1994;Munro-Stasiuk, 2003;Christoffersen et al, 2008). This is, perhaps, surprising because access to the sediments and landforms associated with palaeo-subglacial lakes is relatively easy compared to extant ice sheets.…”

Section: Subglacial Hydrology Of Ice Sheets and Subglacial Lakesmentioning

confidence: 97%

On the reconstruction of palaeo-ice sheets: Recent advances and future challenges

Stokes

Tarasov

Blomdin

et al. 2015

Quaternary Science Reviews

151

104

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Section: Subglacial Hydrology Of Ice Sheets and Subglacial Lakesmentioning

confidence: 97%

On the reconstruction of palaeo-ice sheets: Recent advances and future challenges

Stokes

Tarasov

Blomdin

et al. 2015

Quaternary Science Reviews

151

104

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“…If the near surface orange brown clay from this core represents this*5,000 year period, the increase in organic carbon (LOI) is consistent with deposition during warmer Holocene Climatic Optimum conditions pre 5,000 years BP. This would suggest that the upper 2-3 m thick seismic unit identified in Slave Lake by Christoffersen et al (2008) does indeed represent a Holocene drape, with deglacial or subglacial sedimentary units beneath.…”

mentioning

confidence: 95%

“…Significant sediment deposits ([200 m) have been identified from seismic surveys of the Lake (Christoffersen et al 2008). Near surface sediments (average thickness 2-3 m) appear to represent a Holocene drape (a continuous layer of sediment deposited across the lake floor, often from suspension), with fine grained sediments below the surface layer hypothesised to represent deposition in a subglacial cavity when the lake was covered by the Laurentide Ice Sheet (Christoffersen et al 2008).…”

mentioning

confidence: 98%

“…The established deglaciation chronology suggests that Christie Bay was ice-covered 9,900 14 C years Before Present (BP) (where 14 C refers to radio carbon dates) and that meltwater from the retreating Laurentide Ice Sheet stopped entering Great Slave Lake about 8,400 14 C years BP (Smith 1994). Significant sediment deposits ([200 m) have been identified from seismic surveys of the Lake (Christoffersen et al 2008). Near surface sediments (average thickness 2-3 m) appear to represent a Holocene drape (a continuous layer of sediment deposited across the lake floor, often from suspension), with fine grained sediments below the surface layer hypothesised to represent deposition in a subglacial cavity when the lake was covered by the Laurentide Ice Sheet (Christoffersen et al 2008).…”

mentioning

confidence: 98%

“…The 150 m thick sequences of sediment found in the bottom of Great Slave Lake, have recently been inferred to represent sediments that accumulated in a subglacial lake environment (Christoffersen et al 2008). Sediments deposited at the floor of Antarctic subglacial lakes may contain palaeo-environmental records and evidence of novel microbial life forms.…”

mentioning

confidence: 99%

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Analysis of the microbial community and geochemistry of a sediment core from Great Slave Lake, Canada

Lim

Woodward

Tulaczyk

et al. 2010

Antonie van Leeuwenhoek

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Sediment cores taken from Great Slave Lake, Canada, were analysed to investigate their metabolically active microbial populations and geochemistry. The amplification of cDNA detected metabolically active bacterial (50 separate bands) and archaeal (49 separate band) communities. The bacterial communities were further resolved indicating active actinobacterial and γ-proteobacterial communities (36 and 43 individual bands respectively). Redundancy discriminate analysis and Monte Carlo permutation testing demonstrated the significant impact of geochemical parameters on microbial community structures. Geochemical analyses suggest that the upper 0.4 m represents soil weathering and erosion in the lake catchment. An increase in organic carbon in the lower core suggests either more primary productivity, indicating warmer climate conditions, associated with Holocene Climatic Optimum conditions pre 5,000 years BP or change from a reducing environment in the lower core to an oxidizing environment during more recent deposition. Drivers for bacterial, archaeal and actinobacterial community structures were sediment particle size, and its mineral composition. Depth also significantly affected γ- proteobacterial community structure. In contrast the organic carbon content did not significantly shape the microbial community structures within the sediment. This study indicates that geochemical parameters significantly contribute to microbial community structure in these sediments.

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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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Large subglacial lake beneath the Laurentide Ice Sheet inferred from sedimentary sequences

Cited by 41 publications

References 34 publications

On the reconstruction of palaeo-ice sheets: Recent advances and future challenges

On the reconstruction of palaeo-ice sheets: Recent advances and future challenges

Analysis of the microbial community and geochemistry of a sediment core from Great Slave Lake, Canada

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

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