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Abstract
Due to their potential to support chemolithotrophic life, relic
hydrothermal systems on Mars are a key target for astrobiological
exploration. We analysed water and sediments at six geothermal pools
from the rhyolitic Kerlingarfjöll and basaltic Kverkfjöll volcanoes in
Iceland, to investigate the localised controls on the habitability of
these systems in terms of microbial community function. Our results show
that host lithology plays a minor role in pool geochemistry and
authigenic mineralogy, with the system geochemistry primarily controlled
by deep volcanic processes. We find that by dictating pool water pH and
redox conditions, deep volcanic processes are the primary control on
microbial community structure and function, with water input from the
proximal glacier acting as a secondary control by regulating pool
temperatures. Kerlingarfjöll pools have reduced, circum-neutral CO2-rich
waters with authigenic calcite-, pyrite- and kaolinite-bearing
sediments. The dominant metabolisms inferred from community profiles
obtained by 16S rRNA gene sequencing are methanogenesis, respiration of
sulphate and sulphur (S0) oxidation. In contrast, Kverkfjöll pools have oxidised, acidic (pH < 3) waters with high concentrations of SO42-
and high argillic alteration, resulting in Al-phyllosilicate-rich
sediments. The prevailing metabolisms here are iron oxidation, sulphur
oxidation and nitrification. Where analogous ice-fed hydrothermal
systems existed on early Mars, similar volcanic processes would likely
have controlled localised metabolic potential and thus habitability.
Moreover, such systems offer several habitability advantages, including a
localised source of metabolic redox pairs for chemolithotrophic
microorganisms and accessible trace metals. Similar pools could have
provided transient environments for life on Mars; when paired with
surface or near-surface ice, these habitability niches could have
persisted into the Amazonian. Additionally, they offer a confined site
for biosignature formation and deposition that lends itself well to in
situ robotic exploration.
Original language | English |
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Pages (from-to) | 489-509 |
Number of pages | 21 |
Journal | Geobiology |
Volume | 19 |
Issue number | 5 |
Early online date | 18 Jun 2021 |
DOIs | |
Publication status | Published - Sept 2021 |
Keywords
- Analogue
- Hydrothermal systems
- Iron
- Mars
- Redox
- Sullfur
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Dive into the research topics of 'Volcanic controls on the microbial habitability of Mars-analogue hydrothermal environments'. Together they form a unique fingerprint.Projects
- 1 Finished
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Chemolithotrophs on Mars: metabolic: Chemolithotrophs on Mars: metabolic pathways and biosignatures
Cousins, C. R. (PI) & Zerkle, A. L. (CoI)
Science & Technology Facilities Council
1/10/16 → 31/03/20
Project: Standard