Unraveling Past Submarine Eruptions by Dating Lapilli Tuff-Encrusting Coralligenous (Actea Volcano, NW Sicilian Channel)

Emanuele Lodolo,Barbara Calcinai,Gianluca Quarta,Lucio Calcagnile,Alberto Renzulli,Dario Civile,Carlo Cerrano

doi:10.3389/feart.2021.664591

Abstract

The dating of young submarine volcanic eruptions, with their potential generation of tsunamigenic waves, is essential for a reliable hazard assessment. This is particularly relevant in highly populated coastal areas. The scarce knowledge of the underwater environment makes however, this reconstruction challenging. Our study is focused on the NW sector of the Sicilian Channel, where several small- and medium-size volcanic edifices are present. The only documented Surtseyan-type eruption occurred in A.D. 1831, forming the ephemeral Ferdinandea Island. Late Pleistocene to mid-Holocene eruptions have been up to now only hypothesized, and based solely on indirect data. Here we present the first radiocarbon dates of a coralligenous bioconstruction sampled at 34 m water depth from the summit of the Actea volcano, grown up progressively (up to nowadays) on a lapilli tuff deposit. Actea volcano is a recently discovered pyroclastic cone located at only four nautical miles off the SW coast of Sicily. The oldest age of the bioconstructions that started to encrustate the shallow water pyroclastics shortly after their emplacement (7,387 ± 175 cal years B.P.) represents a terminus ante quem, thus testifying a mid-Holocene submarine eruption in this sector of the Sicilian Channel. This method may be effectively used to bridge the gap between historical accounts and the geological record and thus may contribute to a better volcanic hazard assessment of submarine eruption and related phenomena such as tsunamis.

Highlights

The reconstruction of past submarine volcanic eruptions and their frequency and intensity is of paramount importance to assess the hazard to which coastal areas may be exposed
This study focuses in the central-western sector of the Sicilian Channel, where the only volcanic event documented in historical times is the Ferdinandea Island generated by a Surtseyan-type eruption in A.D. 1831 (Colantoni et al, 1975), and quickly dismantled after a few months
We present for the first time a radiocarbon dating study performed on a fragment of coralligenous encrusting on a lapilli tuff sample recovered in the summit of the Actea volcano, which testifies the occurrence of a mid-Holocene eruption

Summary

INTRODUCTION

The reconstruction of past submarine volcanic eruptions and their frequency and intensity is of paramount importance to assess the hazard to which coastal areas may be exposed. None of these analyses were addressed to direct or indirect datings, making the reconstruction of Quaternary volcanic activity in the NW Sicilian Channel speculative in many aspects This sector of the Sicilian Channel is characterized by a widespread and scattered anorogenic volcanism which occurred mainly during Quaternary, with the build up of the islands of Pantelleria and Linosa, and the formation of a series of submarine edifices located in eastern Adventure Plateau, within Graham Bank and the nearby Terrible Bank and, as recently discovered, a few nautical miles off the SW coast of Sicily (Figure 1; Calanchi et al, 1989; Rotolo et al, 2006; Civile et al, 2015; Coltelli et al, 2016; Cavallaro and Coltelli, 2019; Lodolo et al, 2019a). We present for the first time a radiocarbon dating study performed on a fragment of coralligenous encrusting on a lapilli tuff sample recovered in the summit of the Actea volcano, which testifies the occurrence of a mid-Holocene eruption

METHODOLOGY

RESULTS

DISCUSSION