Abstract

The seabed of the Pontine Archipelago (Tyrrhenian Sea) insular shelf is peculiar as it is characterized by a mixed siliciclastic–carbonate sedimentation. In order to reconstruct the Late Quaternary paleoenvironmental evolution of the Pontine Archipelago, this study investigates the succession of facies recorded by two sediment cores. For this purpose, benthic foraminifera and rhodoliths assemblages were considered. The two cores (post-Last Glacial Maximum in age) were collected at 60 (CS1) and 122 m (Caro1) depth on the insular shelf off Ponza Island. The paleontological data were compared with seismo-stratigraphic and lithological evidence. The cores show a deepening succession, with a transition from a basal rhodolith-rich biodetritic coarse sand to the surface coralline-barren silty sand. This transition is more evident along core Caro1 (from the bottom to the top), collected at a deeper water depth than CS1. In support of this evidence, along Caro1 was recorded a fairly constant increase in the amount of planktonic foraminiferal and a marked change in benthic foraminiferal assemblages (from Asterigerinata mamilla and Lobatula lobatula assemblage to Cassidulina carinata assemblage). Interestingly, the dating of the Caro1 bottom allowed us to extend to more than 13,000 years BP the rhodolith record in the Pontine Archipelago, indicating the possible presence of an active carbonate factory at that time.

Highlights

  • In non-tropical shelf areas, when the terrigenous input rate is low, extensive deposits of skeletal carbonates may accumulate [2]

  • Several studies investigated seabed carbonate sediment from the Pontine Archipelago (Tyrrhenian Sea), focusing on sedimentary features [15,17] and biogenic facies mainly constituted of benthic foraminifera [18,19,20] or coralline red algae [11,16,21,22,23]

  • In the framework of a project dedicated to the Quaternary paleoenvironmental evolution of the Pontine Archipelago, the aim of this study is to investigate the succession of different paleoenvironments recorded by two sediment cores, collected off Ponza Island, by means of the benthic foraminiferal and rhodoliths assemblages

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Summary

Introduction

In non-tropical shelf areas (such as the western Mediterranean), when the terrigenous input rate is low (lower than 10 mm per 1000 years; [1]), extensive deposits of skeletal carbonates may accumulate [2]. Several studies investigated seabed carbonate sediment from the Pontine Archipelago (Tyrrhenian Sea), focusing on sedimentary features [15,17] and biogenic facies mainly constituted of benthic foraminifera [18,19,20] or coralline red algae [11,16,21,22,23]. These studies highlighted the occurrence of precious habitats, such as Posidonia oceanica, coralligenous and rhodolith/maërl beds. Maërl beds are subject to protection measures and the two most common maërl-forming species, Phymatolithon calcareum and Lithothamnion corallioides, are currently included in the Annex V of the EC

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