Spatial and temporal distribution of beach heavy minerals: Mar Chiquita, Argentina

Abstract

Five beach zones, from the backshore out to the breaker zone, were sampled in order to test the spatial distribution and temporal variability of beach heavy minerals retained at the 88–125 μm interval. While heavy minerals dominate to the backshore, light specimens are more abundant in the submerged zones. Opaques dominate among the heavy minerals and are negatively correlated with the translucids. To discriminate beach zones, opaques, the abundance of rock fragments/alterites, amphiboles (non-hornblendiferous) and heavy-mineral percentages are the most sensitive. Seasonal changes are shown by the lighter of the heavy grains (amphiboles, rock fragments, hornblende), and by the light/heavy relationship. Canonically correlated, heavy minerals were recognized as better estimates of zone discrimination than grain-size parameters. The importance of heavy-mineral abundance, to identify drift dispersals and environmental changes, to characterize beach zones and to search for placers based on their spatial and temporal behavior, is stressed.