Abstract

ALIOTTA, Salvador; SPAGNUOLO, Jorge Osvaldo; GINSBERG, Silvia Susana  and  MINOR-SALVATIERRA, Marta. Seafloor morphosedimentology in the entrance sector of Bahía blanca estuary, Argentina. Geoacta [online]. 2014, vol.39, n.2, pp.85-98. ISSN 1852-7744.

In the large Bahia Blanca estuarine system (province of Buenos Aires) there are sectors without a comprehensive assessment of submarine morpho-sedimentological features. Within this context, in this paper the seabed along the north coast of the entrance to the Principal channel of the estuary is studied. Acoustic surveys (echo sounder and side scan sonar) and sediments sampling were performed. The presence of depositional and erosional geoforms was determined. Among those of accretional nature have been established different types of dunes and sand ribbons. The erosive forms are scarps, relatively continuous and irregular, and rocky isolated outcrops. Also, seabed cohesive sediments, both massive and stratified, were differentiated. As anthropogenic forms furrows dredging and the presence of pipes for oil and metal debris were distinguished. The analysis of geoforms and sediments determined that in the east sector of the coastal strip studied prevails sediment transport as bedload towards the Continental Shelf, while in shallow waters of the western sector, there is a marked litoral drift towards the inside of estuary. The conjunction of morphological and sedimentological data allowed to extend the characterization of two ancient coastal levels, indicative of stabilization periods of sea level during the last transgressive process.

Keywords : Bedforms; Sediments; Paleocoasts; Holocene.

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