Modern stromatolites from the Andean lakes: Unlocking ancient stromatolitic sedimentary models
About the Event:
Modern carbonate-stromatolite occurrence has often related with the sea (e.g., Shark Bay, Australia; Exuma Sound, Bahamas in the Caribbean sea) or with littoral pools or channels (e.g., Lagoa Salgada, Brazil; Laguna Bacalar, Mexico; Lagoon Coorong, Australia; Solar Lake, in the Sinai Peninsula, Egypt), always connected with the sea. The discovery of modern gypsum-stromatolites from Cuatro Ciénagas, Mexico, in a continental playa-lake (800 masl) and carbonate-stromatolites in Andean Lakes from Argentina and Chile (more than 3500 masl) have been considered as a significant advance in their scientific knowledge. These stromatolites in the Puna region are been growing in very extreme environmental conditions in the Socompa, Diamante, Tolar Grande and Negra lakes (Argentina) and Tebenquiche and La Brava lakes in Chile. The Puna represents a large basin that is fragmented into a system of minor interrelated basins demarcated by mountains. Its climate is arid, with annual precipitation less than 350 mm, and daily temperatures range from -10 to 20ºC in summer and -15 to 10ºC in winter. Due to its high altitude and low latitude geographical position, the Puna region is exposed to high solar irradiance (~165% of the value at the sea level), especially in the UV-B region, where the instantaneous flux can reach up to 17 W/m2. Due to the extreme environmental conditions, such as residual volcanic activity associated with sulphur availability, hypersalinity, high UV irradiation, low O2 pressure and low nutrient availability, these modern stromatolite-like ecosystems constitute excellent models to study geochemical cycles and biogeochemical interactions during the early Earth. Moreover, these lakes are good laboratories to try to test the hypothesis that similar microbial mat community produce different organosedimentary structures depending of the physico-chemical environmental conditions (Logan´s stromatolite model). By the other hand, during the Precambrian deposition of Villa Mónica Formation, Tandilia System, Argentina, and the Mina Verdún Group, Uruguay, the stromatolite morphology distinguished suggest that the mesoscale arrangements have been produced by the sedimentological condition as Logan´s ideas said.
About the Speaker:
Daniel Gustavo Poiré was born in La Plata, Argentina, in 1953. He degree in Geology in 1979 and he has got the PhD Diploma in Natural Sciences (Geology) in 1987, both at the National University of La Plata. Then (1989-1990), he performed a postdoctoral experience at The University of Liverpool, UK, supervised by T. Peter Crimes. Now he is Full Professor at the National University of La Plata (UNLP) and Principal Researcher at the National Research Council of Argentina (CONICET) at the Centro de Investigaciones Geológicas (UNLP-CONICET). His main interests are modern and ancient organic sedimentary structures (trace fossils, stromatolites and microbial mats) and general sedimentology. He has actively collaborated with geologists, paleontologists and microbiologists in Argentina, Uruguay, Brazil, Bolivia, Paraguay, Peru, England, Wales, Denmark, South Africa, India and USA, and has been involved in numerous published papers and several book chapters. He has lectured several postgraduate courses about sedeimentological significance of trace fossils and stromatolites in Argentina universities and in the University of Barcelona (Spain), and XRD on sedimentary rocks in Argentina. He also participates as a consultant in various projects for oil companies and Portland cement industries.