New different Modern Microbialites deposits in Puna of Catamarca, Argentine

SORIA, MARIANA NOELIA; LENCINA, AGUSTINA INÉS; SAONA, LUIS ALBERTO; STEPANENKO, TATIANA MARIEL; COLLA, MARIA FLORENCIA; FARÍAS, MARÍA EUGENIA

Dijon

Conferencia; Conference and Workshop. Microbialites: formation, evolution, diagenesis.; 2019

Universite Bourgogne, Total

The Puna region (northwest of Argentine) is characterized by an average elevation of about3.7 km asl, with broad depocenters internally drained with hypersaline wetlands, small lakesand salt flats (named as salares) at the center of the basins. The climate can be described as ahigh altitude desert typified by high intensity of solar ultraviolet-B (UV-B) radiation, oxygendepleted atmosphere, strong winds, great daily and seasonally temperature ranges and smallamount of precipitation. These environmental conditions made the wetlands and salt flatsunique extreme environments which resemble the early Earth. During the past decade, wediscovered 21 microbial systems in Argentine Puna, 17 of them are placed in Catamarcaprovince. The following wetlands are in current research: Diamante lake, placed inside thecaldera of Galan volcano; Carachipampa lake, lying at the base of Carachipampa volcano;Pozo Bravo lake, Laguna Verde, Humedal Rojo, eight small pools named as ?Puquios deCampo? and Humedal Las Quinoas, located in the center of the Salar de Antofalla; ElPeinado and Turquesa lagoons at the southern end of the Salar de Antofalla and Río Saladodelta fan at the north of Tres Quebradas lake in Laguna Verde Complex. All thesemicrobialites deposits are located in complex mixed-fluid interactions zones (hypersaline,fresh and hydrothermal waters). Nevertheless, microbialites display a wide range set ofmorphologies. On the one hand, microbial deposits in Salar de Antofalla are represented byevaporitic mat systems dominated by Bacteroidetes and Proteobacteria (Laguna Verde andHumedal Rojo), biostromal megastructures, domal, discoidal and tabular macrostructures(Pozo Bravo), microbial mats dominated by bacteria (Chloroflexi, bacteroidetes,proteobacteria), cyanobacteria and diatoms (Puquios de Campo), and rounded-subroundedand discoidal oncolites (Humedal Las Quinoas); meanwhile, at the end of the alreadymentioned salar biostromal, domal and tabular microbialites are forming paleo and modernlevels in El Peinado and Turquesa lagoons; Las Quinoas oncolites are similar to thoseobserved in Río Salado delta fan; at Carachipampa lake microbialites consist mainly of flatoncolites and microbial accumulations with a flat surface, related to iron and sulfurprecipitates. On the other hand, Diamante lake is one of the most extreme environments dueto its high As concentrations (135 to 300 mgL-1). Isopachous calcium carbonate microlaminaewere observed associated with red haloarchaea biofilms.At present these unique microbialites, oncolites and microbial mats are being studied toimprove our understanding about microbe-mineral interactions, early Earth environmentalconditions and also to promote their protection since salares are being explored in order toseek for enriched lithium chloride deposits.