On the role of sediment compaction and tectonic subsidence in relative sea-level reconstructions – a case study from the Apuo- Versilian coastal plain (NW Mediterranean)

Abstract

This paper investigates the impacts of sediment compaction and tectonic subsidence on Mediterranean relative sea-level (RSL) reconstructions, using as a case study a coastal plain in NW Italy (Apuo-Versilian Plain). We coupled sedimentological and detailed micro and macrofaunal analyses on a 9-m-thick sediment sequence in order to produce two relative sea-level index points and two limiting points. The chronology of these sea-level data was based on a set of new radiocarbon dates performed on organic layers found within the sedimentary sequence. The new dataset allowed for better quantify the role of compaction-driven subsidence in the Apuo-Versilian plain providing evidence that its influence may be more pervasive than is commonly appreciated in medium-sized coastal plains dominated by minerogenic sediments. We discuss that the misfit of the RSL data with existing GIA models in these environmental settings should be accounted for considering the possible role of sediment compaction, so that neglecting to correct for this effect in reconstructing past relative sea levels from the sedimentary record may be critical.