Abstract

BERTOLA, Germán R  and  MOROSI, Martín. Caracterización textural de depósitos de ambientes de marea de la Bahía Samborombón (Buenos Aires, Argentina). Rev. Asoc. Argent. Sedimentol. [online]. 1997, vol.4, n.1, pp.1-13. ISSN 1853-6360.

In Samborombon Bay, with a coastline of almost 144 km of mudflats, littoral processes generate different grain sizes along the coast. These differences obey to the interaction between de La Plata River, the Atlantic Ocean and small rivers and tidal channels from the Salado Basin. There is also an aeolian source from former Pampean sediments and sediments modified by the activity of benthos organisms. To study these tidal environments and the littoral dynamics of the bay, topographic profiles were measured together with systematic sampling. Geomorphology, grain size, mineralogy and organic matter were also analyzed. Grain-size differences can fit within regional and local context: The Rio de La Plata supplies significant amounts of clay to the latitude of Canal 9 inlet. From the South, from Punta Rasa, there is a significant supply of fine sand. Grain-size parameters vary according to sedimentary environments. Due to wave and tidal actions, coarser and less sorted sediments are distributed towards the subtidal sector. The composition of clay minerals is rather uniform along the bay, although it is locally modified by artificial and natural channels. The sand population belongs compositionally to the Austral Association (in the sense of Echechury & Remiro, 1960). Organic matter content in the marsh environment is stable and higher than in other environments, due to the characteristics and increase of biota on the bottom.

Keywords : Tidal flats; Grain size; Mineralogy; Samborombón Bay.

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