Aeromagnetic anomalies reveal hidden tectonic and volcanic structures in the central sector of the Aeolian Islands, southern Tyrrhenian Sea, Italy

Abstract

Salina Island (Italy) in the central Aeolian chain is the northernmost volcanic structure of an elongated ridge on a regional shear zone with NNW‐SSE strike‐slip faults and second‐order N‐S and NE‐SW faults. Modeling of high‐resolution, low‐altitude aeromagnetic data collected in 2003 and 2005 using volcanological data constraints reveals the inner structure of the Salina volcanoes and surrounding marine regions. Regional negative anomalies overlie E‐W elongated sedimentary basins related to the early Pliocene‐Pleistocene opening of the southern Tyrrhenian Sea. These negative anomalies flank positively magnetized crust of Salina and seamounts off its eastern coast where the shorter‐wavelength anomalies map late Pleistocene‐Holocene volcanic conduits, dikes, and faults. The magnetic and volcanological data indicate that the early (circa 168–100 ka) basaltic to andesitic Salina volcanism developed along N‐S and NE‐SW tectonic faults, whereas the more recent andesitic lavas and rhyolitic pyroclastics (circa 100–13 ka) were emitted by vents related to the main NW‐SE faults. The tectonic structures also controlled the location of the seamounts around the island and the geometry of the volcano‐tectonic collapses. Salina volcanism was emplaced on a NNW‐SSE tear fault of the presently developing roll‐back slab in the southern Tyrrhenian Sea.