PMID- 33226839
OWN - NLM
STAT- MEDLINE
DCOM- 20211015
LR  - 20231110
IS  - 1557-8070 (Electronic)
IS  - 1531-1074 (Print)
IS  - 1557-8070 (Linking)
VI  - 21
IP  - 2
DP  - 2021 Feb
TI  - Artificial Maturation of Iron- and Sulfur-Rich Mars Analogues: Implications for 
      the Diagenetic Stability of Biopolymers and Their Detection with Pyrolysis-Gas 
      Chromatography-Mass Spectrometry.
PG  - 199-218
LID - 10.1089/ast.2019.2211 [doi]
AB  - Acidic iron- and sulfur-rich streams are appropriate analogues for the late 
      Noachian and early Hesperian periods of martian history, when Mars exhibited 
      extensive habitable environments. Any past life on Mars may have left behind 
      diagnostic evidence of life that could be detected at the present day. For 
      effective preservation, these remains must have avoided the harsh radiation flux 
      at the martian surface, survived geological storage for billions of years, and 
      remained detectable within their geochemical environment by analytical instrument 
      suites used on Mars today, such as thermal extraction techniques. We investigated 
      the detectability of organic matter within sulfur stream sediments that had been 
      subjected to artificial maturation by hydrous pyrolysis. After maturation, the 
      samples were analyzed by pyrolysis-gas chromatography-mass spectrometry 
      (py-GC-MS) to determine whether organic matter could be detected with this 
      commonly used technique. We find that macromolecular organic matter can survive 
      the artificial maturation process in the presence of iron- and sulfur-rich 
      minerals but cannot be unambiguously distinguished from abiotic organic matter. 
      However, if jarosite and goethite are present in the sulfur stream environment, 
      they interfere with the py-GC-MS detection of organic compounds in these samples. 
      Clay reduces the obfuscating effect of the oxidizing minerals by providing 
      nondeleterious adsorption sites. We also find that after a simple alkali and acid 
      leaching process that removes oxidizing minerals such as iron sulfates, oxides, 
      and oxyhydroxides, the sulfur stream samples exhibit much greater organic 
      responses during py-GC-MS in terms of both abundance and diversity of organic 
      compounds, such as the detection of hopanes in all leached samples. Our results 
      suggest that insoluble organic matter can be preserved over billions of years of 
      geological storage while still retaining diagnostic organic information, but 
      sample selection strategies must either avoid jarosite- and goethite-rich 
      outcrops or conduct preparative chemistry steps to remove these oxidants prior to 
      analysis by thermal extraction techniques.
FAU - Tan, Jonathan S W
AU  - Tan JSW
AD  - Impacts and Astromaterials Research Centre, Department of Earth Science and 
      Engineering, Imperial College London, London, UK.
FAU - Royle, Samuel H
AU  - Royle SH
AD  - Impacts and Astromaterials Research Centre, Department of Earth Science and 
      Engineering, Imperial College London, London, UK.
FAU - Sephton, Mark A
AU  - Sephton MA
AD  - Impacts and Astromaterials Research Centre, Department of Earth Science and 
      Engineering, Imperial College London, London, UK.
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
DEP - 20201123
PL  - United States
TA  - Astrobiology
JT  - Astrobiology
JID - 101088083
RN  - 0 (Biopolymers)
RN  - 70FD1KFU70 (Sulfur)
RN  - E1UOL152H7 (Iron)
SB  - IM
MH  - Biopolymers
MH  - *Exobiology
MH  - Extraterrestrial Environment
MH  - Gas Chromatography-Mass Spectrometry
MH  - Iron
MH  - *Mars
MH  - Pyrolysis
MH  - Sulfur
PMC - PMC7876361
OTO - NOTNLM
OT  - Alkali/Acid leaching
OT  - Artificial maturation
OT  - Biosignature
OT  - Hydrous pyrolysis
OT  - Mars
OT  - py-GC-MS
COIS- No competing financial interests exist.
EDAT- 2020/11/24 06:00
MHDA- 2021/10/16 06:00
PMCR- 2021/02/04
CRDT- 2020/11/23 17:09
PHST- 2020/11/24 06:00 [pubmed]
PHST- 2021/10/16 06:00 [medline]
PHST- 2020/11/23 17:09 [entrez]
PHST- 2021/02/04 00:00 [pmc-release]
AID - 10.1089/ast.2019.2211 [pii]
AID - 10.1089/ast.2019.2211 [doi]
PST - ppublish
SO  - Astrobiology. 2021 Feb;21(2):199-218. doi: 10.1089/ast.2019.2211. Epub 2020 Nov 
      23.