Heavy minerals distribution and provenance in modern beach sands of Campania, Italy

Abstract

The Campania region (southern Italy) is an excellent area to determine the effects of multiple source lithology (volcanic+sedimentary), climate, weathering, transport anddepositional environment on heavy minerals enrichments in the sandy beaches of the coastline between Pozzuoli and Bacoli, and at the Volturno river-mouth. The heavy mineral (HM) assemblage should reflect the clastic supply from the potassic to ultrapotassic lavas and pyroclastic rocks of the Campania and of the Roman Magmatic provinces (Phlegrean Fields, Roccamonfina volcano), and from the recycling of sedimentary - both carbonate and siliciclastic - terranes of the Apennine thrust belt. Opaque oxides, pyroxene and amphibole assemblage dominates in the beach placers of the Campania shoreline - from Bacoli to Pozzuoli - as well as in the Volturno river mouth sands to the north. Modern heavy minerals assemblages reflect clastic contribution from magmatic source rocks whereas contributionfrom sedimentary terranes - exposed extensively in the Volturno river drainage - provide no recycled heavy minerals to the river-mouth sand. Thus, heavy minerals linked to a provenance from the Apennine thrust belt source rocks result diluted and/or unrecognizable using the only HM approach with respect to the minerals provenance sourced by the potassic volcanic fields of Latium and Campania. Thediverse detrital heavy minerals have been characterized describing major stages of progressive chemical weathering, from unweathered to corroded to etched morphologies, a process - in this case-history - playing a minor role in reducing HM diversity through dissolution of moderately stable mineral species.