Preservation of Terrestrial Microorganisms and Organics Within Alteration Products of Chondritic Meteorites from the Nullarbor Plain, Australia
MetadataShow full item record
Funding and Sponsorship
Meteorites that fall to Earth quickly become contaminated with terrestrial microorganisms. These meteorites are out of chemical equilibrium in the environments where they fall, and equilibration promotes formation of low-Temperature alteration minerals that can entomb contaminant microorganisms and thus preserve them as microfossils. Given the well-understood chemistry of meteorites and their recent discovery on Mars by rovers, a similarly weathered meteorite on Mars could preserve organic and fossil evidence of a putative past biosphere at the martian surface. Here, we used several techniques to assess the potential of alteration minerals to preserve microfossils and biogenic organics in terrestrially weathered ordinary chondrites from the Nullarbor Plain, Australia. We used acid etching of ordinary chondrites to reveal entombed fungal hyphae, modern biofilms, and diatoms within alteration minerals. We employed synchrotron X-ray fluorescence microscopy of alteration mineral veins to map the distribution of redox-sensitive elements of relevance to chemolithotrophic organisms, such as Mn-cycling bacteria. We assessed the biogenicity of fungal hyphae within alteration veins using a combination of Fourier-Transform infrared spectroscopy and pyrolysis gas chromatography-mass spectrometry, which showed that alteration minerals sequester and preserve organic molecules at various levels of decomposition. Our combined analyses results show that fossil microorganisms and the organic molecules they produce are preserved within calcite-gypsum admixtures in meteorites. Furthermore, the distributions of redox-sensitive elements (e.g., Mn) within alteration minerals are localized, which qualitatively suggests that climatically or microbially facilitated element mobilization occurred during the meteorite's residency on Earth. If returned as part of a sample suite from the martian surface, ordinary chondrites could preserve similar, recognizable evidence of putative past life and/or environmental change.
Showing items related by title, author, creator and subject.
Geochemical and mineralogical classification of four new shergottites: NWA 10441, NWA 10818, NWA 11043, and NWA 12335Orr, K.J.; Forman, Lucy ; Rankenburg, Kai ; Evans, Noreen ; McDonald, B.J.; Godel, B.; Benedix, Gretchen (2022)Martian meteorites are rare; therefore, the discovery of new meteorites has the potential to significantly expand our current understanding of Mars. In this study, we describe four new shergottites, all found within the ...
Jourdan, Fred; Andreoli, M.; McDonald, I.; Maier, W. (2010)Studies of meteorites are based mostly on samples that fell to Earth in the recent past (i.e., a few million years at most). The Morokweng LL-chondrite meteorite is a particularly interesting specimen as its fall is much ...
Classification of hydrous meteorites (CR, CM and C2 ungrouped) by phyllosilicate fraction: PSD-XRD modal mineralogy and planetesimal environmentsHoward, K.; Alexander, C.; Schrader, D.; Dyl, Kathryn (2014)The relative differences in the degree of hydration should be reflected in any classification scheme for aqueously altered meteorites. Here we report the bulk mineralogies and degree of hydration in 37 different carbonaceous ...