The Northern Argentine Sea

MARCOVECCHIO, J. E.; DE MARCO, S. G.; GAVIO, M. A.; NARVARTE, M.; FIORI, S. M.; GERPE, M

World Seas: An Environmental Evaluation

Elsevier

Lugar: Londres; Año: 2019; p. 759 - 781

The Northern Argentine Sea is part of the Southwestern Atlantic Ocean, extending from ~35°S to 42°S (Fig. 33.1). The continental shelf is with a very low relief and a general slope of less than 0.01 degree. Argentina?s continental margin is longer than 3500km, with an average width of ~400km. It originated during the Late Jurassic-Early Cretaceous (c.140My ago), when the opening of the South Atlantic took place. The width of the shelf within this area varies from ~140 km in the northern area of Río de La Plata outfall, to ~540km at San Matías Gulf (SMG), with maximum depth of 70?80m, reaching ~200m at the shelf edge, to ~160m within the SMG. The main oceanographic features are the encounter of the Brazil and Malvinas/Falkland currents (MCs), producing the Brasil-Malvinas/Falkland Confluence Zone (BMCZ), a complex of mixed waters located between 35°S and 40°S. This region is marked by a strong front formed by the warm, high saline, and low productivity waters of the Brazil Current (BC), and the cold, less saline, and highly productive waters of the MC, and is characterized by intense horizontal and vertical mixing and a seasonal pattern of current intensification and latitudinal instability. In the confluence zone, the subantarctic and subtropical waters mix, forming vortices, meanders, and strong verticaland horizontal temperature and salinity gradients, as well as restricted areas of enhanced chlorophyll build-up, isolated upwelling cells, tongues, and patches of cold or warm waters partly or completely isolated from their water mass of origin, and so on. South of 37°S, three water masses are identified: shelf break (outer shelf) water of relatively high salinity (33.7?34), middle shelf water with relatively low values (33.4?33.6), and coastal (inner shelf) waters with values relatively higher (>34).