Hot springs habitats in Mars-analogs
Hot springs environments contain water, thermal and chemical energy to initiate and sustain variety of microbial life, becoming ideal targets for Mars exploration. Martian opaline rocks around volcanoes present textural and morphological characteristics comparable with terrestrial hot springs and geysers silica sinter deposits.
Bacterial mats around geysers in El Tatio, Atacama: (a) Aerial/drone image of geyser mount, color are associated to microbial organisms adapted a different temperatures; (b) black bacterial mats in distal area at low temperature <40C; (c) terraces with black bacterias at temperature ~50C; (d) orange high temperature bacterial mats in channels at >70C.
Microbial textures in hot-springs deposits
Bacterial mats living around hot springs act as templates for silica precipitation. Palisade fabric is a ubiquitous texture of silica sinter found in low temperature (<40°C) regimes of hot spring environments, and it is formed by filamentous of microorganisms. Repeated alternation in filament directions can form ‘‘stratiform stromatolites’’.
Micro X-Ray tomography (μXRT) is non-destructive technique that produces a 3D high-resolution (1.3μm/voxel) scan of the sinter rock. Preliminary results indicates that the microbes present in the rock are cyanobacteria, which form filaments >2.5 mm long and ~10 μm diameter.
Filaments are covered by silica but not yet fossilized. The volume of bacterial material reached up to 20% of the sample. The total porosity of the sample was estimated to be 50%, and the pores are elongated in the same direction as the filaments. These observations imply that pore structure of could be used as a biosignature.
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