Heavy minerals as tracers on sand beach dynamics: Catania beach (Sicily, Italia)

Abstract

Heavy minerals from Catania beach (Italy) have been analised in 41 sand samples collected along 19 crossshore transepts, with the aim of obtaining information about its source, sorting processes and the main patterns of littoral dynamics. The results show that the major source of beach sediments is the Simeto river, other sources being of lesser importance. The most abundant heavy mineral species are opaque minerals and clinopyroxenes, and they show completely different mechanical and hydrodynamical behaviours, which is due to their differences in density and grain size. Regard to selective sorting processes, it is concluded that wave action and coastline orientation make heavy minerals concentrate in the backshore and at the ends of the beach. Moreover, it has been verified that heavy minerals in the study area tend to concentrate in the cross-shore direction into the finest-grained samples, whereas contour conditions prevent this trend in the longshore direction. It has also been found that the heavy fraction distribution indicates differential longshore sediment transport caused by two opposited longshore currents, one to the north and the other to the south. The first one is more important than the other, probably due to the difference between the fetch of waves approaching from NE and SE directions.