Characterization of Microbialites and Microbial Mats of the Laguna Negra Hypersaline Lake (Puna of Catamarca, Argentina)

BOIDI, FJ; MLEWSKI, ESTELA CECILIA; GOMEZ, FERNANDO JAVIER; GÉRARD, EMMANUELLE

Microbial Ecosystems in Central Andes Extreme Environments

Elsevier

Año: 2019; p. 183 - 203

The Puna-Altiplano region (including northwest Argentina, northern Chile, and southern Bolivia) has become a region of interest to study microbial mineralization processes. The convergence of factors such as extreme environmental conditions, particularly strong negative hydrological balance, favors the development of these mineralizing systems and of extremophile microbial communities. This, together with a favorable local geology and geomorphology, facilitate the formation of closed lakes and groundwater springs that are saturated in minerals, including carbonates. Thus, a highly mineralizing setting together with physicochemical and microbiological processes trigger carbonate precipitation and produce a set of diverse organo-sedimentary structures usually referred to as microbialites). Some of the Puna-Altiplano microbialites resemble those observed in the ancient geological record, for example, stromatolites, which are the oldest evidence of life on Earth. Thus, these microbialite systems provide a unique opportunity to apply an integrated geobiological approach to gain insight to better understand microbial mineralization processes and biosignatures preservation. The Laguna Negra (LN) is an interesting system that caught our attention 10 years ago due to the presence of an extensive plain with abundant carbonate precipitation. The evaporative sedimentary environment, the diversity of microbial mat types, and the combination of physicochemical and microbial processes influencing carbonate precipitation and carbonates geochemistry makes this place an excellent natural laboratory that shows strong similarities with some ancient microbial mineralizing systems, including the Precambrian microbialites of the Tumbiana Formation and the Strelley Pool Chert Formation. Here, some recent findings are summarized to discuss the combination of microbial and physicochemical processes involved in carbonate precipitation and microbialites formation.