Heavy Minerals Distribution and Provenance in Modern Beach and Fluvial Sands of the Betic Cordillera, Southern Spain

Abstract

This study uses heavy detrital minerals to determine actualistic fluvial and beach sand provenance across the Betic Cordillera (Spain), along the coast from Almeria to Marbella. The Betic Cordillera, primarily composed of metamorphic rocks to the east, supply an assemblage dominated by almandine and graphite, with a longshore dispersal from Almeria to Malaga. Buergerite and hypersthene indicate the provenance of calcalkaline lavas east of Cabo de Gata. The western part of the Betic Cordillera, which comprises the Ronda Peridotite Complex, supplies a chromite and diopside assemblage, with a dispersal from Marbella to Algeciras. Considering these mineralogical suites, the effects of source rock compositions and weathering are evaluated. The heavy mineral species mirror the mineralogy of the source rocks of local outcrops and wider source terranes. The fluvial heavy mineral suites do not differ significantly from those in the beaches except for some unstable species. Unstable species such as olivine, pyroxene, and amphibole do not show evidence of loss because of elevated topography and semiarid climate, which do not affect heavy minerals. This contribution also evaluates the potential of some heavy detrital species as ideal pathfinders in searching for diamonds.