En el marco del curso de Posgrado "_Geobiología aplicada a procesos sedimentarios costeros. Ambiente actual_", dictado por la Dra. Diana G. Cuadrado y colaboradores e inscripto en el Departamento de Geología y Secretaría General de Posgrado y Educación Continua de la Universidad Nacional del Sur, los invitamos el martes 8 de junio 17 hs. por medio de plataforma Zoom (https://us02web.zoom.us/j/83336562079?pwd=ajJHTTVzZG9UNytxNHIxU1hMMHN2dz09)

CONFERENCIA NORA NOFFKE

Old Dominion University, Norfolk, VA 23529,

nnoffke@odu.edu _Turbulent lifestyle:_ _Cyanobacteria on Earth's sandy beaches - today and 3 billion years ago_

Modern benthic cyanobacteria are very well adapted to the harsh hydraulic conditions of sandy tidal environments. The microbial interaction with the physical sediment dynamics originates the characteristic 'microbially induced sedimentary structures (MISS)'. The structures do not resemble stromatolites at all, and have been classified as their own group of structures. MISS occur not only today, but they are abundant in shallow-marine sandstones of all Earth ages including the early Archean time. A fossil tidal flat preserved in the 2.9 billion years old Archean Pongola Supergroup, South Africa, corresponds to the tidal flats that today form along the coast of the North Atlantic Ocean. This ancient tidal flat includes microbial mat-related structures of exceptional beauty. Those MISS record the same types of microbial mats as we find today in our modern tidal environments. The fossil MISS have in statistical analyses the same geometries and dimensions like the modern ones. The fossil MISS include microstructures that are identical to the microstructures in the modern MISS. The fossil MISS have the same pattern of distribution within the ancient tidal flats like the modern MISS in equivalent modern tidal flats. We conclude that the complicated biotic-physical processes that lead to the specific MISS and their typical distribution cannot be mimicked by the activities of other prokaryotes than cyanobacteria. Therefore, the microbial mats of the Pongola Supergroup may include the oldest known cyanobacteria in Earth's history. Their high diversity suggests a much earlier start of evolution of cyanobacteria than assumed before.

Geobiología en el IADO: https://www.youtube.com/watch?v=rEjPiKdqxX4