Interactions between volcanism and tectonics in the western Aeolian sector, southern Tyrrhenian Sea

Abstract

S U M M A R YNew high-resolution bathymetric and magnetic data from the western Aeolian sector, southern Tyrrhenian Sea, provide insights into structural and volcanic development of the area, suggesting a strong interaction between volcanism and tectonics. The analysis of these data combined with relocated earthquake distribution, focal plane solutions and strain rate evaluation indicates that the dextral strike-slip Sisifo-Alicudi shear zone is a complex and wide area of active deformation, representing the superficial expression of the deep seated lithospheric tear fault separating the subduction slab below Sicily and Calabria. Most of the observed volcanic features are aligned along a NW-SE trend, such as the Filicudi island-Alicudi North Seamount and Eolo-Enarete alignments, and are dissected by hundred-metre-high scarps along conjugate NNE-SSW trending fault systems. The magnetic field pattern matches the main trends of volcanic features. Spectral analysis and Euler deconvolution of magnetic anomalies show the existence of both deep and shallow sources. High-amplitude, high-frequency anomalies due to shallow sources are dominant close to the volcanic edifices of Alicudi and Filicudi, while the main contribution on the surrounding Eolo, Enarete, Alicudi North and Filicudi North seamounts is given by low-amplitude anomalies and/or deeper magnetic sources. This is probably related to different ages of the volcanic rocks, although hydrothermal processes may have played an important role in blanketing magnetic anomalies, in particular at Enarete and Eolo seamounts. Relative chronology of the eruptive centres and the inferred deformation pattern outline the Quaternary evolution of the western Aeolian Arc: Sisifo, Alicudi North and Filicudi North seamounts might have developed in an early stage, following the Late Pliocene-Early Pleistocene SE-ward migration of arc-related volcanism due to the Ionian subduction hinge retreat; Eolo, Enarete and Filicudi represent later manifestations that led volcanoes to develop during Mid-Late Pleistocene, when the stress regime in the area changed, due to the SSE-ward propagation of the subduction slab tear fault and the consequent reorientation and decrease of trench migration velocity. Finally, volcanic activity occurred in a very short time span at Alicudi, where an almost conical volcanic edifice emerged, suggesting negligible interactions with regional fault systems.

Geophysical investigation of Pleistocene volcanism and tectonics offshore Capo Vaticano (Calabria, southeastern Tyrrhenian Sea)

“…Indeed, the deaf acoustic character and the lack of internal reflectors within seismic Unit V (Figs. 3 and 7) is frequently observed on seismic profiles acquired across submarine volcanic edifices, for instance, the nearby Aeolian islands volcanoes A c c e p t e d M a n u s c r i p t (Bortoluzzi et al, 2010 and references therein), the Canary islands (Gee et al, 2001) or the volcanic units forming the Vema Ridge (Bonatti et al, 2005).…”

“…This is the case of the Southern Apennines fold and thrust belt -Italian region and the adjacent Tyrrhenian back arc basin system, which is accompanied by the development of the volcanic arc of Aeolian Islands, widely documented in literature (e.g. Gabbianelli et al, 1990;, and reference therein; Romagnoli et al, 2009;Ventura et al, 1999;Bortoluzzi et al, 2010).…”

“…This is the case of the Southern Apennines fold and thrust belt -Tyrrhenian back arc basin system, which is accompanied by the development of the volcanic arc of Aeolian Islands, widely documented in literature (e.g. Gabbianelli et al, 1990;Marani et al, 2004, and reference therein;Romagnoli et al, 2009;Ventura et al, 1999;Bortoluzzi et al, 2010). More recently, on the basis of integrated seismic tomography data and kinematic reconstructions, a model for Plio-Quaternary magmatism of the Tyrrhenian area in the context of the regional geodynamics has been proposed by Rosenbaum et al (2008).…”

The tectonic puzzle of the Messina area (Southern Italy): Insights from new seismic reflection data

“…This different behaviour is marked particularly by the subduction hinge which is moving away with respect to the upper plate (i.e., Sardinia) along the Calabrian side, whereas it converges relative to Sardinia in the Sicilian side of the subduction zone11. This is coherent with the contractional setting in the northern Sicilian offshore1213. The Messina Strait is shaped by a complex network of normal and transtensional transfer faults1415161718 (Fig.…”

Propagation of a lithospheric tear fault (STEP) through the western boundary of the Calabrian accretionary wedge offshore eastern Sicily (Southern Italy)

“…Onshore NE of Sicily, a set of geological features suggest the presence at depth of a STEP type lithospheric tear-fault. The dextral Taormina Line (AmodioMorelli et al, 1976;Rosenbaum and Lister, 2004;Rosenbaum et al, 2008) and the TindariLipari (TL) line (Guarnieri, 2004;Billi et al, 2006;Guarnieri, 2006;Bortoluzzi et al, 2010) have been proposed to be the crustal expression in upper plate of a STEP fault (Figure 2), that accommodate the remaining active portion of the slab beneath Calabria (Billi et al, 2006). In fact, recent GPS measurements show that a small amount of east-west extension still occurs in the Tyrrhenian basin, but only in its south-eastern most sector (Serpelloni et al, 2005;Serpelloni et al, 2007).…”