Subsurface imaging reveals a confined aquifer beneath an ice-sealed Antarctic lake

Dugan, Hilary A.; Doran, Peter T.; Tulaczyk, S. M.; Mikucki, Jill A.; Arcone, Steven A.; Auken, Esben; Schamper, Cyril; Virginia, Ross A.

doi:10.1002/2014gl062431

Cited by 34 publications

(36 citation statements)

References 34 publications

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Section: Discussionmentioning

confidence: 93%

“…The level of Lake Vida has risen 3.5 m in the last 40 years (Doran, 2015) and has a hydrologic history similar to Lake Bonney (Fig. 8), which has been documented to have risen ∼ 16 m from 1903 to 2010 (Chinn, 1993;Doran, 2015). If a linear extrapolation is applied to the Vida record based on the correlation of volumetric change to Lake Bonney, the surface of Lake Vida would have risen ∼ 7.7 m from 1903 to 2010 when our cores were collected.…”

Section: Discussionmentioning

confidence: 99%

“…Located in the McMurdo dry valleys of Antarctica, Lake Vida has the thickest ice of any subaerial lake on Earth and is one of the few "ice-sealed" ecosystems known to support a diverse and active microbial population in a cold, anoxic, aphotic brine (Murray et al, 2012;Dugan et al, 2015). The brine was first discovered 16 m below the surface of Lake Vida and is hypothesized to have been sealed from the atmosphere for several millennia .…”

Section: Introductionmentioning

confidence: 99%

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Stratigraphy of Lake Vida, Antarctica: hydrologic implications of 27 m of ice

et al. 2015

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Abstract. Lake Vida, located in Victoria Valley, is one of the largest lakes in the McMurdo dry valleys and is known to contain hypersaline liquid brine sealed below 16 m of freshwater ice. For the first time, Lake Vida was drilled to a depth of 27 m. Below 21 m the ice is marked by well-sorted sand layers up to 20 cm thick within a matrix of salty ice. From ice chemistry, isotopic composition of δ 18 O and δ 2 H, and ground penetrating radar profiles, we conclude that the entire 27 m of ice formed from surface runoff and the sediment layers represent the accumulation of surface deposits. Radiocarbon and optically stimulated luminescence dating limit the maximum age of the lower ice to 6300 14 C yr BP. As the ice cover ablated downwards during periods of low surface inflow, progressive accumulation of sediment layers insulated and preserved the ice and brine beneath, analogous to the processes that preserve shallow ground ice. The repetition of these sediment layers reveals hydrologic variability in Victoria Valley during the mid-to late Holocene. Lake Vida is an exemplar site for understanding the preservation of subsurface brine, ice, and sediment in a cold desert environment.

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Section: Discussionmentioning

confidence: 93%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Stratigraphy of Lake Vida, Antarctica: hydrologic implications of 27 m of ice

et al. 2015

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“…For example, the commercial airborne SkyTEM system was able to map brine-saturated sediments a few hundred metres thick in the Dry Valleys, including those below a range of glaciers flowing into Taylor Valley (Dugan et al 2015;Mikucki et al 2015;Foley et al 2016). However, these glaciers are less than 400 m thick, whereas in most areas of Antarctica the ice is much thicker and sedimentary basins much deeper.…”

Section: Groundwater Detection Delineation and Quantification In Submentioning

confidence: 99%

Antarctic subglacial groundwater: a concept paper on its measurement and potential influence on ice flow

Siegert

Kulessa

Bougamont

et al. 2017

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Is groundwater abundant in Antarctica and does it modulate ice flow? Answering this question matters because ice streams flow by gliding over a wet substrate of till. Water fed to icestream beds thus influences ice-sheet dynamics and, potentially, sea-level rise. It is recognized that both till and the sedimentary basins from which it originates are porous and could host a reservoir of mobile groundwater that interacts with the subglacial interfacial system. According to recent numerical modelling, up to half of all water available for basal lubrication, and time lags between hydrological forcing and ice-sheet response as long as millennia, may have been overlooked in models of ice flow. Here, we review evidence in support of Antarctic groundwater and propose how it can be measured to ascertain the extent to which it modulates ice flow. We present new seismoelectric soundings of subglacial till, and magnetotelluric and transient electromagnetic forward models of subglacial groundwater reservoirs. We demonstrate that multifaceted and integrated geophysical datasets can detect, delineate and quantify the groundwater contents of subglacial sedimentary basins and, potentially, monitor groundwater exchange rates between subglacial till layers. The paper thus describes a new area of glaciological investigation and how it should progress in future.Gold Open Access: This article is published under the terms of the CC-BY 3.0 license. Water beneath the ice sheetAntarctic ice-sheet flow is fundamentally affected by water at the bed, as it reduces basal friction to encourage sliding and weakens till to enable bed deformation. Subglacial hydrology -the flow of water beneath the ice -is therefore a key element of the ice-sheet system. Studies to date on subglacial hydrology, and its impact on ice flow, have concentrated on water at or very near to the bed of the ice sheet.Basal water modulation of ice flow can be achieved in a number of ways. Over an impermeable bed, water can flow through channels cut either downwards into the substrate or upwards into the ice. Enhanced basal water pressures may occur where the channels and their linkages are distributed, increasing overriding ice flow through a reduction in the substrate's effective pressure. Conversely, where a well-organized channel system is formed, water pressures are lower and the hydrological effect on ice flow is reduced. If the ice stream rests on permeable subglacial till, its strength can affect ice flow as controlled by porewater pressures. High pressures lead to a reduction in material strength by pushing till grains apart, reducing bed friction and thus

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“…Because the MDV contain high-resistivity ice and low-resistivity brines, there exists a large EM-resistivity contrast between frozen ground and ground containing liquid brine (Dugan et al, 2015a;Mikucki et al, 2015). This paper presents results from the first airborne electromagnetic (AEM) survey in Antarctica, performed in November 2011 in select locales in the MDV, and it expands on the technical aspects of the AEM system, with comparisons to other techniques and past geophysical exploration.…”

Section: Introductionmentioning

confidence: 99%

Helicopter-borne transient electromagnetics in high-latitude environments: An application in the McMurdo Dry Valleys, Antarctica

et al. 2016

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The McMurdo Dry Valleys are a polar desert in coastal Antarctica, where glaciers, permafrost, ice-covered lakes, and ephemeral summer streams coexist. Liquid water is found at the surface only in lakes and in the temporary streams that feed them. Past geophysical exploration has yielded ambiguous results regarding the presence of subsurface water. In 2011, we used a helicopter-borne, time-domain electromagnetic (TDEM) sensor to map resistivity in the subsurface across the Dry Valleys. The airborne electromagnetic (AEM) method excels at finding subsurface liquid water in polar deserts, where water remains liquid under cold conditions if it is sufficiently saline, and therefore electrically conductive. Over the course of 26 h of helicopter time, we covered large portions of the Dry Valleys and vastly increased our geophysical understanding of the subsurface, particularly with respect to water. Our data show extensive subsurface low-resistivity layers approximately 150–250 m below the surface and beneath higher resistivity layers. We interpret the low-resistivity layers as geologic materials containing freeze-concentrated or “cryoconcentrated” hyper saline brines lying beneath glaciers and frozen permafrost. These brines appeared to be contiguous with surface lakes, subglacial regions, and the Ross Sea, which could indicate a regional-hydrogeologic system, wherein solutes might be transported between surface reservoirs by ionic diffusion and subsurface flow. The presence of such brines underneath glaciers might have implications for glacier movement. Systems such as this, where brines exist beneath glacial ice and frozen permafrost, may exist elsewhere in coastal Antarctica; AEM resistivity is an ideal tool to find and survey them. Our application of TDEM demonstrates that in polar subsurface environments containing conductive brines, such a diffusive electromagnetic method is superior to radar surveying in terms of depth of penetration and ability to differentiate hydrogeologic conditions.

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Subsurface imaging reveals a confined aquifer beneath an ice-sealed Antarctic lake

Cited by 34 publications

References 34 publications

Stratigraphy of Lake Vida, Antarctica: hydrologic implications of 27 m of ice

Stratigraphy of Lake Vida, Antarctica: hydrologic implications of 27 m of ice

Antarctic subglacial groundwater: a concept paper on its measurement and potential influence on ice flow

Helicopter-borne transient electromagnetics in high-latitude environments: An application in the McMurdo Dry Valleys, Antarctica

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