Exploring Low-Temperature Dolomite as a Biosignature

Carbonates are prevalent in the geologic record throughout Earth's history and are also found on Mars and within meteorites. The chemical and isotopic compositions of carbonates have been used to elucidate the composition of ancient oceans and the prevailing conditions during the development of life and its subsequent rapid evolution^1-5. Carbonate mineral compositions reflect the environmental conditions under which they were formed^4,5 .

 

Dolomite is particularly abundant in ancient rock formations but is scarce in modern sedimentary environments. Many ancient dolomites are suspected of being alteration products of preexisting dolomite phases rather than being originally formed, unaltered dolomites⁶. The geochemical and neomorphic alteration of dolomite have been studied extensively, with the principal driving forces for neomorphism being the inherent thermodynamic instability of non-stoichiometric dolomites and the surface free energy-driven recrystallization of fine crystalline mosaics to coarser crystalline⁶.  Recent studies have demonstrated that microorganisms can produce dolomite with a geochemical signature distinct from those formed abiotically^1-4. Our research integrates field studies, state-of-the-art laboratory experiments, mineralogical, and geochemical analyses to investigate the processes and environmental conditions that control the chemical composition of low-temperature carbonates. The role of inorganic-organic interactions is evaluated in natural field laboratories and carefully controlled laboratory experiments performed under abiotic and biotic conditions.

 

In summary, the research focuses on understanding the processes and environmental conditions that control the chemical composition of low-temperature dolomite. A multidisciplinary approach, integrating field studies, laboratory experiments, microscopic, mineralogical, and geochemical analyses, is employed to investigate the role of inorganic-organic interactions in the formation of these carbonates. This work has the potential to provide insights into the development of life on Earth and the evolution of terrestrial and Martian carbonates.

 

References:

[1] Sánchez-Román M., et al. (2011) Chemical Geology 281, 143 - 150.

[2] Sánchez-Román M., et al. (2014) Scientific Reports 4, 4767.

[3] Sanchez-Roman M., et al (2023) Geochimica et Cosmochimica Acta 356, 66-82.

[4] Sánchez-Román M., et al. (2011) Geochimica et Cosmochimica Acta 75, 887-904.

[5] Li M., et al. (2021) Geology 49, 698–702.

[6] Mazzullo, S.J., et al. (1991) Carbonates Evaporites 7, 21–37.