Mineral matrix effects on pyrolysis products of kerogens infer difficulties in determining biological provenance of macromolecular organic matter at Mars

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Title: Mineral matrix effects on pyrolysis products of kerogens infer difficulties in determining biological provenance of macromolecular organic matter at Mars
Authors: Royle, SH
Salter, TL
Watson, JS
Sephton, M
Item Type: Journal Article
Abstract: Ancient martian organic matter is likely to take the form of kerogen-like recalcitrant macromolecular organic matter (MOM), existing in close association with reactive mineral surfaces, especially iron oxides. Detecting and identifying a biological origin for martian MOM will therefore be of utmost importance for life detection efforts at Mars. We show that Type I and Type IV kerogens provide effective analogues for putative martian MOM of biological and abiological (meteoric) provenances respectively. We analyse the pyrolytic breakdown products when these kerogens are mixed with mineral matrices highly relevant for the search for life on Mars. We demonstrate that, using traditional thermal techniques as generally used by the Sample Analysis at Mars and Mars Organic Molecule Analyser instruments, even the breakdown products of highly recalcitrant MOM are transformed during analysis in the presence of reactive mineral surfaces, particularly iron. Analytical transformation reduces the diagnostic ability of this technique, as detected transformation products of both biological and abiological MOM may be identical (low molecular weight gas phases and benzene) and indistinguishable. The severity of transformational effects increased through: calcite < kaolinite < haematite < nontronite < magnetite < goethite. Due to their representation of various habitable aqueous environments and the preservation potential of organic matter by iron, it is not advisable to completely avoid iron-rich strata. We conclude that haematite-rich localities, with evidence of extensive aqueous alteration of originally reducing phases, such as the Vera Rubin Ridge, may be relatively promising targets for identifying martian biologically-sourced MOM.
Issue Date: 10-May-2022
Date of Acceptance: 9-Jan-2022
URI: http://hdl.handle.net/10044/1/94287
DOI: 10.1089/ast.2021.0074
ISSN: 1531-1074
Publisher: Mary Ann Liebert
Start Page: 1
End Page: 21
Journal / Book Title: Astrobiology
Volume: 22
Issue: 5
Copyright Statement: © Mary Ann Liebert, Inc.
Sponsor/Funder: Science and Technology Facilities Council (STFC)
Science and Technology Facilities Council
UK Space Agency
Funder's Grant Number: ST/N000560/1
EACPR_P89346
ST/V006134/1
Keywords: Science & Technology
Physical Sciences
Life Sciences & Biomedicine
Astronomy & Astrophysics
Biology
Geosciences, Multidisciplinary
Life Sciences & Biomedicine - Other Topics
Geology
Thermal decomposition
Mineral matrix effects
Mars life detection
Pyrolysis
MSL
ExoMars 2022
GALE CRATER
IN-SITU
OIL SHALES
THERMAL TRANSFORMATION
ULTRAVIOLET-RADIATION
CHEMICAL EVOLUTION
CATALYTIC CRACKING
CALCIUM-CARBONATE
MASS-SPECTROMETER
LIPID BIOMARKERS
ExoMars 2022
MSL
Mars life detection
Mineral matrix effects
Pyrolysis
Thermal decomposition
Exobiology
Extraterrestrial Environment
Iron
Macromolecular Substances
Mars
Minerals
Pyrolysis
Iron
Minerals
Macromolecular Substances
Exobiology
Extraterrestrial Environment
Mars
Pyrolysis
Astronomy & Astrophysics
0201 Astronomical and Space Sciences
0402 Geochemistry
0403 Geology
Publication Status: Published
Embargo Date: 2023-05-21
Online Publication Date: 2022-05-10
Appears in Collections:Earth Science and Engineering
Faculty of Engineering