Modern stromatolite ecosystems at alkaline and hipersalyne high-altitude lakes in the Argentinean Puna

Abstract

Modern stromatolites have been so far recorded i) an hypersaline region of Hamelin Pool, Shark Bay in Western Australia , ii) shallow subtidal regions at the margin of Exuma Sound in the Bahamas , iii) fresh-water areas at the Cuatro Ciénagas basin in Mexico; and iv) Yellowstone Hot Spring. All of these locations are situated at the sea level where microorganisms cope with little or no stress conditions. In turn, in the dessertic region of Salta, Northwestern Argentina, near the border of Chile we have found characteristic stromatolite-like ecosystems laying and developing in shallow hypersaline lakes located above 4,000 metters, under the pressure of harsh conditions, very similar to the ones present in the Early´s Earth atmosphere. The aim of this work is to make the first description of extreme living stromatolites surviving above 4,000 metters at Laguna Socompa. The environment, morphological description, preliminary biological and mineralogical composition of these new modern stromatolites are presented in this study.