Storm Dispersal of Volcanogenic Sands from Buenos Aires, Where Heavy-Metal Concentrations Are Heavy-Mineral Segregations

摘要

The southeastern beaches and inner shelf of the Buenos Aires coastline are dominated by storms coming from the south and southeast. Erosion is dominant at the coastal chiffs and abrasion platforms, while deposition is extended below the 9-m contour depth. In relation to sand abundance on the inner shelf there is a northward transition between shelly sand sheets, a fine-sand ribbon field, and sand ridges with oblique megaripples. Side-scan records indicate the selective sorting processes that lead to grain size diminishing to the north, and heavy-mineral enrichment, either at the beach or on the shelf These storm-induced effects should be considered when evaluating placers on the inner shelf or monitoring the heavy-metal content in sediments. Two-way analyses of variance (ANOVA) tests were used to establish the grain-size effects on heavy-metal analysis.