Palaeoshoreline records of glacial isostatic adjustment in the Dry Valleys region, Antarctica

Konfal, S. A.; Wilson, T. J.; Hall, Brenda L.

doi:10.1144/sp381.26

Cited by 3 publications

(2 citation statements)

References 57 publications

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“…Remnants of Pleistocene and Holocene age glacial lakes, such as lake sediments, palaeo‐shorelines and perched deltas have been documented throughout the MDV (e.g. Péwé, ; Clayton‐Greene, ; Doran et al ., ; Kelly et al ., ; Hall & Denton, ; Hall et al ., ; Konfal et al ., ). The MDV palaeo‐lake sediments generally are organic‐rich silty sands with gravel that are commonly interbedded with carbonates and/or gypsum (e.g.…”

Section: Discussionmentioning

confidence: 97%

In a PICL: The sedimentary deposits and facies of perennially ice‐covered lakes

et al. 2018

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Perennially ice-covered lakes can have significantly different facies than open-water lakes because sediment is transported onto the ice, where it accumulates, and sand grains preferentially melt through to be deposited on the lake floor. To characterize the facies in these lakes, sedimentary deposits from five Antarctic perennially ice-covered lakes were described using lakebottom observations, underwater video and images, and sediment cores. One lake was dominated by laminated microbial mats and mud (derived from an abutting glacier), with disseminated sand and rare gravel. The other four lakes were dominated by laminated microbial mats and moderately well to moderately sorted medium to very coarse sand with sparse granules and pebbles; they contained minor interstitial or laminated mud (derived from streams and abutting glaciers). The sand was disseminated or localized in mounds and 1 m to more than 10 m long elongate ridges. Mounds were centimetres to metres in diameter; conical, elongate or round in shape; and isolated or deposited near or on top of one another. Sand layers in the mounds had normal, inverse, or no grading. Nine mixed mud and sand facies were defined for perennially ice-covered lakes based on the relative proportion of mud to sand and the style of sand deposition. While perennially ice-covered lake facies overlap with other ice-influenced lakes and glaciomarine facies, they are characterized by a paucity of grains coarser than granules, a narrow range in sand grain sizes, and inverse grading in the sand mounds. These facies can be used to infer changes in ice cover through time and to identify perennially ice-covered lakes in the rock record. Ancient perennially icecovered lakes are expected on Earth and Mars, and their characterization will provide new insights into past climatic conditions and habitability.

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Section: Discussionmentioning

confidence: 97%

In a PICL: The sedimentary deposits and facies of perennially ice‐covered lakes

et al. 2018

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“…Baker 2002). Teller & Thorleifson 1983;Lewis et al 2005;Konfal et al 2013) and patterns of palaeoglacial retreat have been significantly improved by elucidating palaeo-ice-marginal lake geography, evolution and drainage (Jansson 2003;Etienne et al 2006;Carrivick & Tweed 2013). Reconstructions of glacioisostatic rebound (e.g.…”

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confidence: 99%

Refining the pattern and style of Cordilleran Ice Sheet retreat: palaeogeography, evolution and implications of lateglacial ice‐dammed lake systems on the southern Fraser Plateau, British Columbia, Canada

Perkins

Brennand

2014

Boreas

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Decay of the last Cordilleran Ice Sheet (CIS) near its geographical centre has been conceptualized as being dominated by passive downwasting (stagnation), in part because of the lack of large recessional moraines. Yet, multiple lines of evidence, including reconstructions of glacio‐isostatic rebound from palaeoglacial lake shoreline deformation suggest a sloping ice surface and a more systematic pattern of ice‐margin retreat. Here we reconstructed ice‐marginal lake evolution across the subdued topography of the southern Fraser Plateau in order to elucidate the pattern and style of lateglacial CIS decay. Lake stage extent was reconstructed using primary and secondary palaeo‐water‐plane indicators: deltas, spillways, ice‐marginal channels, subaqueous fans and lake‐bottom sediments identified from aerial photograph and digital elevation model interpretation combined with field observations of geomorphology and sedimentology, and ground‐penetrating radar surveys. Ice‐contact indicators, such as ice‐marginal channels, and grounding‐line moraines were used to refine and constrain ice‐margin positions. The results show that ice‐dammed lakes were extensive (average 27 km2; max. 116 km2) and relatively shallow (average 18 m). Within basins successive lake stages appear to have evolved by expansion, decanting or drainage (glacial lake outburst flood, outburst flood or lake maintenance) from southeast to northwest, implicating a systematic northwestward retreating ice margin (rather than chaotic stagnation) back toward the Coast Mountains, similar in style and pattern to that proposed for the Fennoscandian Ice Sheet. This pattern is confirmed by cross‐cutting drainage networks between lake basins and is in agreement with numerical models of North American ice‐sheet retreat and recent hypotheses on lateglacial CIS reorganization during decay. Reconstructed lake systems are dynamic and transitory and probably had significant effects on the dynamics of ice‐marginal retreat, the importance of which is currently being recognized in the modern context of the Greenland Ice Sheet, where >35% of meltwater streams from land‐terminating portions of the ice sheet end in ice‐contact lakes.

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Glacial isostatic adjustment and post-seismic deformation in Antarctica

Wal

Barletta

Nield

et al. 2022

Memoirs

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This paper reviews glacial isostatic adjustment (GIA) and postseismic deformation in Antarctica. It discusses numerical models and their inputs, and observations and inferences that have been made from them. Both processes are controlled by mantle viscosity but their forcings are different. Ongoing GIA can be is mainly induced by the loss of ice since the last glacial maximum (LGM) equivalent to 5 to 15 m of global sea level rise. However, mantle viscosity is so low in parts of West Antarctica (∼10 18 Pa s) that ice thickness changes in the last centuries and decades control the current uplift rates there. The uplift due to GIA has promoted ice sheet stability after the LGM, and in West Antarctica GIA is a significant negative feedback on the current decline of the ice sheet. The postseismic deformation following the 1998 earthquake near the Balleny Islands south of New Zealand has been detected in GPNSS data and compared to model outputs. The best fitting viscosity for this area is ∼ 10 19 Pa s, similar to GIA-based estimates for the Antarctic Peninsula. Future work should focus on unifying descriptions of viscosity across geodynamic models, and integrating information from seismic, gravity, experimental and geological data.

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Palaeoshoreline records of glacial isostatic adjustment in the Dry Valleys region, Antarctica

Cited by 3 publications

References 57 publications

In a PICL: The sedimentary deposits and facies of perennially ice‐covered lakes

In a PICL: The sedimentary deposits and facies of perennially ice‐covered lakes

Refining the pattern and style of Cordilleran Ice Sheet retreat: palaeogeography, evolution and implications of lateglacial ice‐dammed lake systems on the southern Fraser Plateau, British Columbia, Canada

Glacial isostatic adjustment and post-seismic deformation in Antarctica

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