Foucher, F. and Westall, F.
Astrobiology 13 (1) 57-67
par Frapart - publié le , mis à jour le
Opaline silica was detected, with Raman spectroscopy, in carbonaceous microfossils (especially Myxococcoides) in silicified filamentous microbial mats within dolomitized conglomerates of the Draken Formation (- 800 to - 700 Ma). High-resolution electron microscopy (HRTEM) and microprobe analyses were used to confirm the nature of this phase in the quartz matrix of the microbial mats. The silica likely precipitated in a icrocrystalline form onto the organic macromolecules around, and within, the degrading microorganisms and preserved them by inhibiting the natural phase change to quartz. The Raman signal of opaline silica associated with carbonaceous matter and other iosignatures could be a potential indicator of biogenicity. This kind of association could be very useful during the future ExoMars mission (ESA/Roscosmos, 2018) that will earch for traces of past life on Mars.