P024-0002
Serpentinized Ultramafic Rocks and Biogeochemical Comparisons – Planets Earth and Mars

Wednesday, 9 December 2020
Poster
Antonio de Morais, Brazilian Center of Physics Research and Universidade Federal Fluminense, COSMO and Lagemar, respectively, Rio de Janeiro, Brazil, Susanna E Sichel, LAGEMAR UFF, Niteroi, Brazil, Thomas Campos, UFRN, Natal, Brazil, Adriana Ocampo, NASA Headquarters, Washington, DC, United States and Guillermo Alvarado-Induni, PYSA ICE, Apdo, Costa Rica
Abstract:
Recent research shows that Earth serpentinization of cooled ultramafic rocks (peridotites and komatiites) produces H2 as chemical byproduct for the metabolism of chemosynthetic microorganisms, and their fossilized remains can be found in carbonaceous veins. Both rock types are present at Mars (see SNC meteorites such as NWA1950), indicating an early stage of planetary evolution of very high temperature ultramafic magmas, which may have enabled habitats conducive to life.

In order to explore the possible early occurrence and probable habitats for life at Mars, we compared geochemical data from ultramafic samples (peridotites) from the Saint Peter and Saint Paul archipelago (SPSP), Atlantic Ocean, and komatiites from Gorgona island, Colombia, and from Tortugal, Costa Rica, with available chemical Mars data. We observed that, among peridotites and komatiites, the komatiites from Gorgona and Tortugal are geochemically similar to the Martian shergottites meteorites, despite the greater concentration of Martian FeOt.

Thus, chemosynthetic microorganisms which evolved in similar geochemical environments, could also have used the same kind of geochemistry of komatiitic-like environments at Mars, if life (hypothetically) arose there.

We collected ultramafic samples of fresh and serpentinized mantellic peridotites from SPSP Atlantic Ocean, and komatiites from Tortugal, Costa Rica. We will search for possible biochemical signatures (organic biomolecules and biomineralizations), possible microfossils (<10 μm) and fossilized colonies of chemosynthetic microorganisms within the samples. We will present the results of the biogeochemical comparisons.


Whether or not we find microfossils, we propose that at Mars: a) in an epoch when there was plenty of surface liquid water and plume-type volcanism on the planet, then there could have been a possibility that chemosynthetic microorganisms could had evolved, using H2 from serpentinization of komatiite-like lavas; and b) they could have been fossilized in those mafic/ultramafic rocks on the “red planet”.


Thus, we would like to suggest that NASA Perseverance rover Team considers collecting samples of serpentinized komatiite-like lavas and possible serpentinized peridotite-like rocks in the search for biosignatures and in situ microfossils.

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