Late Quaternary Landscape Dynamics at the La Spezia Gulf (NW Italy): A Multi-Proxy Approach Reveals Environmental Variability within a Rocky Embayment

Veronica Rossi,Andrea Cocchianella,Simon Trigona,Luca Lorenzini,Marco Marchesini,Gianfranco Valle,Alessandro Amorosi,Silvia Marvelli,Monica Bini

doi:10.3390/w13040427

Veronica Rossi, Andrea Cocchianella + Show 7 more

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https://doi.org/10.3390/w13040427

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Abstract

The Gulf of La Spezia (GLS) in Northwest Italy is a rocky embayment with low fluvial influence facing the Mediterranean Sea. Past landscape dynamics were investigated through a multi-proxy, facies-based analysis down to a core depth of 30 m. The integration of quantitative ostracod, foraminifera, and pollen analyses, supported by radiocarbon ages, proved to be a powerful tool to unravel the late Quaternary palaeoenvironmental evolution and its forcing factors. The complex interplay between relative sea-level (RSL), climatic changes, and geomorphological features of the embayment drove four main evolution phases. A barrier–lagoon system developed in response to the rising RSL of the Late Pleistocene (likely the Last Interglacial). The establishment of glacial conditions then promoted the development of an alluvial environment, with generalised erosion of the underlying succession and subsequent accumulation of fluvial strata. The Holocene transgression (dated ca. 9000 cal year BP) caused GLS inundation and the formation of a low-confined lagoon basin, which rapidly turned into a coastal bay from ca. 8000 cal year BP onwards. This latter environmental change occurred in response to the last Holocene stage of global sea-level acceleration, which submerged a morphological relief currently forming a drowned barrier-island complex in the embayment.

Highlights

Mediterranean coastal areas include a variety of aquatic and wetland environments and habitats that deserve to be protected against the threat of global change through the application of rigorous conservation or restoration plans, based on both monitoring techniques and geological data [1,2,3]
The eight facies associations identified in this study are based on the integration of sedimentological and palaeobiological data from the reference core SP, which is considered representative of the 30 m-thick subsurface succession of the study area (Figure 2)
A multi-proxy approach including sedimentological analysis integrated with meiofauna, pollen content and radiocarbon dating was applied to the 30 m-thick succession of core SP, in the eastern part of the Gulf of La Spezia (GLS), a relatively deep embayment protected by steep promontories

Summary

Introduction

Mediterranean coastal areas include a variety of aquatic and wetland environments and habitats (swamps, marshes, lakes, lagoons, bays, etc.) that deserve to be protected against the threat of global change through the application of rigorous conservation or restoration plans, based on both monitoring techniques and geological data [1,2,3]. Palaeoenvironmental reconstructions of embayments/lagoons located along rocky shorelines or of drowned estuaries are relatively scarce [11,17,18,19], since wide, low-lying coastal plains have drawn the most attention. Geomorphological studies of rocky shores are rapidly increasing, especially in the Mediterranean, where rocky cliffs, platforms, and rock pools represent more than 50% of coastline habitat types [20]. Rocky shores include several landforms such as platforms/marine terraces, tidal notches, and cliffs, which can provide potential RSL markers or data in terms of erosion rates and decay/shaping processes [20,21,22,23,24]

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