STORM RECORDS IN TIDAL SEDIMENTATION: ROLE OF MICROBIAL MATS

CUADRADO, D.; PRATOLONGO, P.

Puerto Madryn

Conferencia; Tidalites 2015. 9th International Conference on Tidal Sedimentology; 2015

AAS-CENPAT

The objective of this research is to compare two sedimentarydeposits affected by exceptional storm events. The microbial mat colonization is altered by high-energy events, as revealed by its special configuration. We studied the interaction between physical-hydrodynamic processesand microbial mats, which may be used to infer the relative energy of a depositional environment in the sedimentary record.In the Bahia Blanca Estuary, a strong storm occurred in July 2010. It was characterized by strong winds (sustained winds ranging 40 to 70 km h−1) blowing from the SW for several days. This weather conditions were responsible for an increase in wave height (2 - 3 m), as well as higher tidal levels. Under these circumstances, seawater reached the supratidal area at a higher frequency, and inundation occurred at high tide for several consecutive days. Hydrodynamic forces acting on the microbial mat resulted in a particular set of MISS preserved on the supratidal zone, like microbial erosional pockets, flipped-over edges structures, and microbial chips. Even though we registered a strong hydroclimatic event, biostabilization prevented erosion and may have enhanced sedimentation on the tidal plain, as evidenced by a change in the size gradation.