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Quantifying Preservation Potential: Lipid Degradation in a Mars-Analog Circumneutral Iron Deposit
- Source :
- Astrobiology. 21(6)
- Publication Year :
- 2021
-
Abstract
- Comparisons between the preservation potential of Mars-analog environments have historically been qualitative rather than quantitative. Recently, however, laboratory-based artificial maturation combined with kinetic modeling techniques have emerged as a potential means by which the preservation potential of solvent-soluble organic matter can be quantified in various Mars-analog environments. These methods consider how elevated temperatures, pressures, and organic-inorganic interactions influence the degradation of organic biomarkers post-burial. We used these techniques to investigate the preservation potential of deposits from a circumneutral iron-rich groundwater system. These deposits are composed of ferrihydrite (Fe5HO8 · 4H2O), an amorphous iron hydroxide mineral that is a common constituent of rocks found in ancient lacustrine environments on Mars, such as those observed in Gale Crater. Both natural and synthetic ferrihydrite samples were subjected to hydrous pyrolysis to observe the effects of long-term burial on the mineralogy and organic content of the samples. Our experiments revealed that organic-inorganic interactions in the samples are dominated by the transformation of iron minerals. As amorphous ferrihydrite transforms into more crystalline species, the decrease in surface area results in the desorption of organic matter, potentially rendering them more susceptible to degradation. We also find that circumneutral iron-rich deposits provide unfavorable conditions for the preservation of solvent-soluble organic matter. Quantitative comparisons between preservation potentials as calculated when using kinetic parameters show that circumneutral iron-rich deposits are ∼25 times less likely to preserve solvent-soluble organic matter compared with acidic, iron-rich environments. Our results suggest that circumneutral iron-rich deposits should be deprioritized in favor of acidic iron- and sulfur-rich deposits when searching for evidence of life with solvent extraction techniques.
- Subjects :
- Life Sciences & Biomedicine - Other Topics
010504 meteorology & atmospheric sciences
Extraterrestrial Environment
Iron
Mars
Hydrous pyrolysis
Astronomy & Astrophysics
01 natural sciences
Ferrihydrite
chemistry.chemical_compound
Artificial maturation. Astrobiology 21, xxx–xxx
Desorption
0103 physical sciences
Biosignature
Artificial maturation
0201 Astronomical and Space Sciences
Exobiology
0402 Geochemistry
Organic matter
Geosciences, Multidisciplinary
010303 astronomy & astrophysics
Biology
0105 earth and related environmental sciences
chemistry.chemical_classification
Minerals
Mineral
Science & Technology
Chemistry
Geology
Agricultural and Biological Sciences (miscellaneous)
Lipids
0403 Geology
Space and Planetary Science
Environmental chemistry
Physical Sciences
Hydroxide
Kinetic parameters
Life Sciences & Biomedicine
Groundwater
Subjects
Details
- ISSN :
- 15578070
- Volume :
- 21
- Issue :
- 6
- Database :
- OpenAIRE
- Journal :
- Astrobiology
- Accession number :
- edsair.doi.dedup.....bfbf752b3605d27a55006491193c28ac