Microbial mats and stromatolites in high-altitude Andean lakes of Catamarca (Argentina): microbe-mineral interactions in an environmental analogue for Early Earth and Mars

GOMEZ, F.J., KAH, L.C., BARTLEY, J.K., AND ASTINI, R.A.,

Santiago

Congreso; Congreso Geológico Chileno; 2009

Facultad de Ciencias Fisicas y Matemáticas Universidad de Chile

Geobiological and astrobiological research focuses on understanding microbial life and its roles in Earth history, in order to increase our understanding about the environmental requirements for life, the biological limits for life, and the implications for planetary habitability – most specifically on the early Earth and Mars. Unfortunately, complex relationships among physical, chemical and biological processes, as well as the oftentimes obscuring of detail by postdepositional diagenetic processes, makes it difficult to clearly differentiate biogenic, abiogenic, and potentially biologically mediated signatures. Analysis of present-day environmental analogues to early Earth and Mars may represent the most effective means of distinguishing the roles played by these physical, chemical and biological processes and discriminating between their geologic signatures. High-altitude Andean lakes (>4000 m above sea-level) are considered to represent some of the Earth’s best analogues for early Earth and Mars [1] because: (1) they rest upon basic volcanic rocks and thus are similar in composition to the dominant planetary crustal materials; (2) their altitude results in extremes in temperature and UV radiation that are similar to planetary systems with limited atmospheric protection; and (3) they experience extremes in salinity and dryness that represent significant challenges to the establishment of active biological systems. In this study we present some preliminary results of ongoing geobiological research on living microbial mats, mineralized stromatolites, and lake waters of high-altitude lakes of the Salar de la Laguna Verde Complex, Catamarca Province, Argentina. In this lake system, hypersaline lake waters and microbial communities interact to form a variety of mineralized microfabrics (mat-dominated fabrics and mineral precipitates). Information on the chemistry of lake waters, evaporite deposits, and mineralized microbial structures, will ultimately help decipher the microbial-mineral interactions in this complex ecosystem.