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Proceedings Paper

Chemical and structural composition of organic carbonaceous structures in Tissint: evidence for a biogenetic origin
Author(s): Jamie Wallis; N. C. Wickramasinghe; Daryl H. Wallis; Nori Miyake; M. K. Wallis; Richard B. Hoover
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Paper Abstract

Earlier studies of the Tissint Martian meteorite identified the presence of a number of 5-50μm carbonaceous spherical structures. SEM and EDS elemental spectra for 11 selected structures confirmed that they comprise of a carbonaceous outer coating with a inner core of FeS2 (pyrite) and are characterised as immiscible globules with curved boundaries. Here we report on the results of Raman spectroscopic studies that unambiguously confirm the mantle as comprising of ‘disordered carbonaceous material’. R1 = ID/IG against ΓD (cm-1) band parameter plots of the carbonaceous coatings imply a complex precursor carbon inventory comparable to the precursor carbon component of materials of known biotic source (plants, algae, fungi, crustaceans, prokaryotes). Correlation between peak metamorphic temperatures and Raman D-band (ΓD) parameters further indicate the carbonaceous component was subjected to a peak temperature of ~250 OC suggesting a possible link with the hydrothermal precipitation processes responsible for the formation of similar globules observed in hydrothermal calcite veins in central Ireland. Ω G (cm-1), ΓG (cm-1), Ω D (cm-1) and ΓD (cm-1) parameters further imply a level of crystallinity and disorder of the carbon component consistent with carbonaceous material recovered from a variety of non-terrestrial sources. Cl, N, O and S to C elemental ratios are typical of high volatility bituminous coals and distinctly higher than equivalent graphite standards.

Paper Details

Date Published: 22 September 2015
PDF: 12 pages
Proc. SPIE 9606, Instruments, Methods, and Missions for Astrobiology XVII, 96060L (22 September 2015); doi: 10.1117/12.2186515
Show Author Affiliations
Jamie Wallis, Cardiff Univ. (United Kingdom)
N. C. Wickramasinghe, The Univ. of Buckingham (United Kingdom)
Daryl H. Wallis, The Univ. of Buckingham (United Kingdom)
Nori Miyake, The Univ. of Buckingham (United Kingdom)
M. K. Wallis, The Univ. of Buckingham (United Kingdom)
Richard B. Hoover, The Univ. of Buckingham (United Kingdom)
Athens State Univ. (United States)


Published in SPIE Proceedings Vol. 9606:
Instruments, Methods, and Missions for Astrobiology XVII
Richard B. Hoover; Gilbert V. Levin; Alexei Yu. Rozanov; Nalin C. Wickramasinghe, Editor(s)

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