Authigenic clays as precursors to carbonate precipitation in saline lakes of Salar de Llamara, Northern Chile

Abstract The Salar de Llamara, Atacama Desert is host to saline lakes known as Puquios, which are possible analogs for on early Earth or Mars. Here we examine associations between microbial communities, Mg-clay minerals, and carbonates in mat samples from the Puquios using scanning electron microscopy, energy dispersive X-ray spectroscopy, focused ion beam nanotomography, transmission microscopy. We observe micrometer-scale aggregates of nanocrystalline around cyanobacterial cell sheaths throughout alveolar networks extracellular polymeric substances. High-Mn calcite occupies pore spaces surfaces within clay matrix. propose a sequence whereby substance serve precipitation Mg-clay, permineralizes original microorganisms. Formation reduces kinetic barriers provides suitable substrate formation carbonate minerals. therefore suggest that authigenic clays important preservation communities non-marine settings such Desert.