Carbonate, remains a long-standing enigma because of its high abundance in Precambrian rocks and rarity in modern settings. Recently, microbial experiments successfully formed dolomite under Earth surface conditions suggesting dolomite and other mixed carbonates [(Ca,Mg,Fe)(CO3)2] are potential biosignatures. This research will investigate if and how microorganisms control the mineralogy and the geochemistry of carbonate minerals that grow at low temperatures (<50° C) to define these minerals as proxies of the paleo-conditions of formation. The study area will mainly be in a hypersaline system in Fuente de Piedra (SW Spain), one of few places of present-day dolomite formation, and perform biotic and abiotic laboratory experiments that mimic natural environments (i.e., vary temperature, pH, salinity, etc.)._x000d_
The main aim of this project is to confirm that mixed carbonates represent solid proxies of biological activity that can be used to determine specific environmental conditions for formation of unaltered Terrestrial and Martian carbonates. This points out the understanding of mechanisms in carbonate formation in natural systems, which are of fundamental importance not only for understanding modern environments but also as a window into the geologic past of Earth and potentially Mars.

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