español LA MORFOLOGÍA DE LA BAHÍA DE SAMBOROMBÓN (ARGENTINA): SU VÍNCULO CON LA EVOLUCIÓN DE LA CUENCA DEL SALADO Y LA NEOTECTÓNICA DE LA LLANURA PAMPEANA

The morphology of the Samborombón Bay (Argentina): its link with the evolution of the Salado Basin and the Pampeana plain neotectonic

Abstract

Samborombón Bay is located on the Bonaeranse coast, in the estuary of the River Plate. It has a characteristic semicircular morphology, approximately 100 km long, between Punta Piedras (to the north) and Cape San Antonio (to the south). The coincidence with the underlying Salado Basin makes it possible to trace time-space relationships between its morphology and its tectonosedimentary history. Andean exhumation brought sediments to the Atlantic passive margin. In the Pliocene there was a decrease in the rate of sedimentation due to the filling in of the environments of the Pampean Plain. The interposition of the Córdoba alluvial fan against the San Guillermo High generated the Mar Chiquita Lagoon and changes in drainage. Thus, the Las Chilcas Formation (Maastrichtian-Paleocene) sedimentation rate of ~0.09 mm/year is reduced to ~0.005 mm/year of the Puelches Formation (Pliocene-Pleistocene), with an average of 0.042 mm/year for the Eocene Los Cardos and Olivos formations. The progressive negative balance between the rate of sedimentation vs. subsidence determines that the Salado Basin is a hungry (highly receptive) depocenter that has led to the advance of the sea inland into Samborombón Bay. In this way, there are conch strands, wetlands, shallows and marshes where the development of highlands from the south favored progressive continentalization.