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Volcanogenic fluvial-lacustrine environments in iceland and their utility for identifying past habitability on Mars.

Cousins C - Life (Basel) (2015)

Bottom Line: The availability of liquid water coupled with the potential longevity of such systems renders these localities prime targets for the future exploration of Martian biosignatures.This meltwater can be stored to create subglacial, englacial, and proglacial lakes, or be released as catastrophic floods and proglacial fluvial systems.Sedimentary deposits produced by the resulting fluvial-lacustrine activity are extensive, with lithologies dominated by basaltic minerals, low-temperature alteration assemblages (e.g., smectite clays, calcite), and amorphous, poorly crystalline phases (basaltic glass, palagonite, nanophase iron oxides).

View Article: PubMed Central - PubMed

Affiliation: UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh, Mayfield Road, Edinburgh EH9 3JZ, UK. c.cousins@ed.ac.uk.

ABSTRACT
The search for once-habitable locations on Mars is increasingly focused on environments dominated by fluvial and lacustrine processes, such as those investigated by the Mars Science Laboratory Curiosity rover. The availability of liquid water coupled with the potential longevity of such systems renders these localities prime targets for the future exploration of Martian biosignatures. Fluvial-lacustrine environments associated with basaltic volcanism are highly relevant to Mars, but their terrestrial counterparts have been largely overlooked as a field analogue. Such environments are common in Iceland, where basaltic volcanism interacts with glacial ice and surface snow to produce large volumes of meltwater within an otherwise cold and dry environment. This meltwater can be stored to create subglacial, englacial, and proglacial lakes, or be released as catastrophic floods and proglacial fluvial systems. Sedimentary deposits produced by the resulting fluvial-lacustrine activity are extensive, with lithologies dominated by basaltic minerals, low-temperature alteration assemblages (e.g., smectite clays, calcite), and amorphous, poorly crystalline phases (basaltic glass, palagonite, nanophase iron oxides). This paper reviews examples of these environments, including their sedimentary deposits and microbiology, within the context of utilising these localities for future Mars analogue studies and instrument testing.

No MeSH data available.


Related in: MedlinePlus

Examples of lacustrine environments and deposits. (a) Subaerial lake Kverkfjallalón (2011) surrounded by sulfate and smectite-rich sediment [41]; (b) Hillshaded terrestrial laser scanner image of the sediment fan at Gígjökulslón, 2010 following the eruption of Eyjafjallajökull (image credit: Stuart Dunning) [60]; (c) Galtarlón, ice free, July 2007 (image credit: Katherine Joy), lake approximately 300 m across at its widest point; (d) Galtarlón, ice covered, June 2011 (image credit: Barry Herschy); (e) Oblique view of the Gígjökulslón sedimentary fan looking towards the fan source, marked by black star (image credit: Stuart Dunning, [60]).
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life-05-00568-f004: Examples of lacustrine environments and deposits. (a) Subaerial lake Kverkfjallalón (2011) surrounded by sulfate and smectite-rich sediment [41]; (b) Hillshaded terrestrial laser scanner image of the sediment fan at Gígjökulslón, 2010 following the eruption of Eyjafjallajökull (image credit: Stuart Dunning) [60]; (c) Galtarlón, ice free, July 2007 (image credit: Katherine Joy), lake approximately 300 m across at its widest point; (d) Galtarlón, ice covered, June 2011 (image credit: Barry Herschy); (e) Oblique view of the Gígjökulslón sedimentary fan looking towards the fan source, marked by black star (image credit: Stuart Dunning, [60]).

Mentions: Ice-bound englacial lakes sustained by hydrothermal activity provide a subaerial counterpart to the subglacial lakes detailed above, which are more readily accessible for sampling and research. Hydrothermal input into these lakes includes active hot springs and fumaroles within and around the shore of the lake [56]. At the Kverkfjöll volcano on the northern margin of Vatnajökull, the ~300 m diameter englacial hydrothermal lake Kverkfjallalón, locally also named Gengissig, is sustained by geothermal heating in between periodic drainage events, the most recent of which occurred in August 2013, producing a small jökulhlaup following a phreatic event [57]. Geothermal heating of this lake keeps it seasonally ice-free (Figure 4a), with summertime (June 2011) temperatures between 10–20 °C at the lake shore [41]. The microbiology from one sample taken at 4 m depth within this lake was found to be dominated almost entirely by the aerobic betaproteobacterium Xenophilus, a microorganism common to glacial environments [55]. However, for elucidating comparable metabolisms that could have operated within Martian lacustrine environments, where only anaerobic metabolisms are likely to have been feasible, englacial subaerial lakes such as Kverkfjallalón benefit from hydrothermal input, which results in localized anoxia or reduced dissolved oxygen (DO) at points of direct hydrothermal interaction or mixing, contrasting with the oxic areas of the lake. For example, DO at the lake edge measured in 2011 ranged from 0.8–3.9 mg/L [41]. Coupled with the availability of dissolved sulfate [41] (Figure 3), this provides a natural laboratory within which to investigate anaerobic chemolithotrophy within a lacustrine setting as a model for past Martian ecosystems. Indeed, glaciovolcanic landforms at Arsia Mons suggest that such an englacial lake was sustained through volcanic heating, potentially for hundreds to thousands of years [39]. Adjacent to Kverkfjallalón is a younger ice-dammed lake (locally termed “Galtarlón”). This clear blue lake (Figure 4c) has not yet been investigated with regards to its resident biota, but the clarity of the lake water suggests this environment will be highly nutrient limited, similar to supraglacial lakes observed on Greenlandic ice sheets [58]. These lakes represent low temperature hydrothermal lacustrine environments, with geochemical inputs driven by passive leaching of bioessential dissolved ions (e.g., Si, Ca, Na, Fe, Mg) from the underlying basaltic bedrock, mixing with hydrothermal fluids draining into the lake [41,53], and by active volcanic degassing of CO2, H2S, and H2 [56]. One major factor that may have differed between englacial lakes on Earth and lacustrine environments on Mars is the potential presence of sustained ice cover on Martian lakes, and the effect of this on sunlight and delivery of exogenous nutrients. However, given that phototrophy has not been identified as the primary means of production within the indigenous microbial communities present within Kverkfjallalón [55], and that both Kverkfjallalón and nearby Galtarlón typically lose their ice-cover predominantly during summer months (and some years not at all, Figure 4c,d), which has the benefit of improving accessibility for sampling, this difference does not detract from the value of these sites as a suitable microbial analogue.


Volcanogenic fluvial-lacustrine environments in iceland and their utility for identifying past habitability on Mars.

Cousins C - Life (Basel) (2015)

Examples of lacustrine environments and deposits. (a) Subaerial lake Kverkfjallalón (2011) surrounded by sulfate and smectite-rich sediment [41]; (b) Hillshaded terrestrial laser scanner image of the sediment fan at Gígjökulslón, 2010 following the eruption of Eyjafjallajökull (image credit: Stuart Dunning) [60]; (c) Galtarlón, ice free, July 2007 (image credit: Katherine Joy), lake approximately 300 m across at its widest point; (d) Galtarlón, ice covered, June 2011 (image credit: Barry Herschy); (e) Oblique view of the Gígjökulslón sedimentary fan looking towards the fan source, marked by black star (image credit: Stuart Dunning, [60]).
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4390869&req=5

life-05-00568-f004: Examples of lacustrine environments and deposits. (a) Subaerial lake Kverkfjallalón (2011) surrounded by sulfate and smectite-rich sediment [41]; (b) Hillshaded terrestrial laser scanner image of the sediment fan at Gígjökulslón, 2010 following the eruption of Eyjafjallajökull (image credit: Stuart Dunning) [60]; (c) Galtarlón, ice free, July 2007 (image credit: Katherine Joy), lake approximately 300 m across at its widest point; (d) Galtarlón, ice covered, June 2011 (image credit: Barry Herschy); (e) Oblique view of the Gígjökulslón sedimentary fan looking towards the fan source, marked by black star (image credit: Stuart Dunning, [60]).
Mentions: Ice-bound englacial lakes sustained by hydrothermal activity provide a subaerial counterpart to the subglacial lakes detailed above, which are more readily accessible for sampling and research. Hydrothermal input into these lakes includes active hot springs and fumaroles within and around the shore of the lake [56]. At the Kverkfjöll volcano on the northern margin of Vatnajökull, the ~300 m diameter englacial hydrothermal lake Kverkfjallalón, locally also named Gengissig, is sustained by geothermal heating in between periodic drainage events, the most recent of which occurred in August 2013, producing a small jökulhlaup following a phreatic event [57]. Geothermal heating of this lake keeps it seasonally ice-free (Figure 4a), with summertime (June 2011) temperatures between 10–20 °C at the lake shore [41]. The microbiology from one sample taken at 4 m depth within this lake was found to be dominated almost entirely by the aerobic betaproteobacterium Xenophilus, a microorganism common to glacial environments [55]. However, for elucidating comparable metabolisms that could have operated within Martian lacustrine environments, where only anaerobic metabolisms are likely to have been feasible, englacial subaerial lakes such as Kverkfjallalón benefit from hydrothermal input, which results in localized anoxia or reduced dissolved oxygen (DO) at points of direct hydrothermal interaction or mixing, contrasting with the oxic areas of the lake. For example, DO at the lake edge measured in 2011 ranged from 0.8–3.9 mg/L [41]. Coupled with the availability of dissolved sulfate [41] (Figure 3), this provides a natural laboratory within which to investigate anaerobic chemolithotrophy within a lacustrine setting as a model for past Martian ecosystems. Indeed, glaciovolcanic landforms at Arsia Mons suggest that such an englacial lake was sustained through volcanic heating, potentially for hundreds to thousands of years [39]. Adjacent to Kverkfjallalón is a younger ice-dammed lake (locally termed “Galtarlón”). This clear blue lake (Figure 4c) has not yet been investigated with regards to its resident biota, but the clarity of the lake water suggests this environment will be highly nutrient limited, similar to supraglacial lakes observed on Greenlandic ice sheets [58]. These lakes represent low temperature hydrothermal lacustrine environments, with geochemical inputs driven by passive leaching of bioessential dissolved ions (e.g., Si, Ca, Na, Fe, Mg) from the underlying basaltic bedrock, mixing with hydrothermal fluids draining into the lake [41,53], and by active volcanic degassing of CO2, H2S, and H2 [56]. One major factor that may have differed between englacial lakes on Earth and lacustrine environments on Mars is the potential presence of sustained ice cover on Martian lakes, and the effect of this on sunlight and delivery of exogenous nutrients. However, given that phototrophy has not been identified as the primary means of production within the indigenous microbial communities present within Kverkfjallalón [55], and that both Kverkfjallalón and nearby Galtarlón typically lose their ice-cover predominantly during summer months (and some years not at all, Figure 4c,d), which has the benefit of improving accessibility for sampling, this difference does not detract from the value of these sites as a suitable microbial analogue.

Bottom Line: The availability of liquid water coupled with the potential longevity of such systems renders these localities prime targets for the future exploration of Martian biosignatures.This meltwater can be stored to create subglacial, englacial, and proglacial lakes, or be released as catastrophic floods and proglacial fluvial systems.Sedimentary deposits produced by the resulting fluvial-lacustrine activity are extensive, with lithologies dominated by basaltic minerals, low-temperature alteration assemblages (e.g., smectite clays, calcite), and amorphous, poorly crystalline phases (basaltic glass, palagonite, nanophase iron oxides).

View Article: PubMed Central - PubMed

Affiliation: UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh, Mayfield Road, Edinburgh EH9 3JZ, UK. c.cousins@ed.ac.uk.

ABSTRACT
The search for once-habitable locations on Mars is increasingly focused on environments dominated by fluvial and lacustrine processes, such as those investigated by the Mars Science Laboratory Curiosity rover. The availability of liquid water coupled with the potential longevity of such systems renders these localities prime targets for the future exploration of Martian biosignatures. Fluvial-lacustrine environments associated with basaltic volcanism are highly relevant to Mars, but their terrestrial counterparts have been largely overlooked as a field analogue. Such environments are common in Iceland, where basaltic volcanism interacts with glacial ice and surface snow to produce large volumes of meltwater within an otherwise cold and dry environment. This meltwater can be stored to create subglacial, englacial, and proglacial lakes, or be released as catastrophic floods and proglacial fluvial systems. Sedimentary deposits produced by the resulting fluvial-lacustrine activity are extensive, with lithologies dominated by basaltic minerals, low-temperature alteration assemblages (e.g., smectite clays, calcite), and amorphous, poorly crystalline phases (basaltic glass, palagonite, nanophase iron oxides). This paper reviews examples of these environments, including their sedimentary deposits and microbiology, within the context of utilising these localities for future Mars analogue studies and instrument testing.

No MeSH data available.


Related in: MedlinePlus