Fluid Inclusion Studies of Chemosynthetic Carbonates: Strategy for Seeking Life on Mars

Abstract

Fluid inclusions in minerals hold the potential to provide important data on the chemistry of the ambient fluids during mineral precipitation. Especially interesting to astrobiologists are inclusions in low-temperature minerals that may have been precipitated in the presence of microorganisms. We demonstrate that it is possible to obtain data from inclusions in chemosynthetic carbonates that precipitated by the oxidation of organic carbon around methane-bearing seepages. Chemosynthetic carbonates have been identified as a target rock for astrobiological exploration. Other surficial rock types identified as targets for astrobiological exploration include hydrothermal deposits, speleothems, stromatolites, tufas, and evaporites, each of which can contain fluid inclusions. Fracture systems below impact craters would also contain precipitates of minerals with fluid inclusions. As fluid inclusions are sealed microchambers, they preserve fluids in regions where water is now absent, such as regions of the martian surface. Although most inclusions are < 5 microns, the possibility to obtain data from the fluids, including biosignatures and physical remains of life, underscores the advantages of technological advances in the study of fluid inclusions. The crushing of bulk samples could release inclusion waters for analysis, which could be undertaken in situ on Mars.

Isotopic and geochemical investigation of two distinct Mars analog environments using evolved gas techniques in Svalbard, Norway

“…However, shallow marine sediments associated with methane seeps representing chemolithotrophic ecosystems, such as those present in fossilized form at Knorringfjell, are an analog for one possible biological community that may have been preserved in shallow marine sediments during the Noachian on Mars (Fairen et al, 2005;Komatsu and Ori, 2000;Parnell et al, 2002). Fossil methane seeps have also been associated with the presence of methane hydrates, which have been suggested as sources of methane to the martian atmosphere (Komatsu et al, 2011).…”

The role of Raman spectroscopy as an astrobiological tool in the exploration of Mars

“…98 Ambient fluids are enclosed and preserved in micrometre-sized chambers as remnants of the environmental conditions when the microchambers became sealed, or at a later time when fluids flowed through rock along fractures (association of the inclusion with a fracture is the differentiating factor). Such fluid inclusions can remain liquid above 100°C.…”

Preservation of Microborings as Fluid Inclusions

“…By being sheltered in hard substrates, these microbes could perhaps be shielded from the extreme conditions. We believe that materials from Mars are likely to be rich in carbonate minerals (McKay & Nedell 1988, Kempe & Kazmierczak 1997, Parnell et al 2002. Because microborings form easily in carbonate minerals on Earth, one might postulate that Martian carbonates would be fertile ground for the preservation of extraterrestrial microbial traces.…”