Fault-controlled deep hydrothermal flow in a back-arc tectonic setting, SE Tyrrhenian Sea

Abstract

Understanding magmatic systems and deep hydrothermal circulation beneath arc-volcanoes provides insights into deep processes associated with slab-subduction and mantle-wedge partial melting. Here we analyze hydrothermal flow below a structural high (Capo Vaticano Ridge, CVR) located offshore Capo Vaticano (western Calabria) and affected by magmatic intrusions generated from above the Ionian subducting-slab. In order to explain observations, we combine geophysical and numerical modelling results. Fluid-flow modelling shows that temperature distribution and geothermal gradient are controlled mainly by hydrothermal circulation, in turn affected by heat source, fault pattern, rock permeability, basement topography and sediment thickness. Two main faults, shaping the structural high and fracturing intensely the continental crust, enable deep hydrothermal circulation and shallow fluid discharge. Distribution of seismicity at depth supports the hypothesis of a slab below Capo Vaticano, deep enough to enable mantle-wedge partial melting above the subduction zone. Melt migration at shallow levels forms the magmatic intrusions inferred by magnetic anomalies and by δ3He enrichment in the discharged fluids at the CVR summit. Our results add new insights on the southern Tyrrhenian Sea arc-related magmatism and on the Calabrian inner-arc tectonic setting dissected by seismogenic faults able to trigger high-destructive earthquakes.

Extensional tectonics during the Tyrrhenian back‐arc basin formation and a new morpho‐tectonic map

“…The final Quaternary phase (Figure 9d) is dominated by the building of Vavilov volcano (2.4–0.1 Ma; Sartori, 2005 and references therein), by the opening of the Marsili Basin (see ODP 650 in Figure 3; Kastens et al., 1988) and by the build‐up of the central Marsili volcano (age ranging from 0.7 Ma; Marani & Trua, 2002; to 0.003 Ma; see Iezzi et al., 2014). The opening of the Marsili back‐arc basin is coeval with the formation of the Aeolian volcanic arc whose spatial evolution is linked to the decoupling and roll‐back of the slab below the Calabrian Arc (De Astis, Ventura, & Vilardo, 2003; Bortoluzzi et al., 2010; Loreto et al., 2019). Along the eastern/southeastern Tyrrhenian Basin, a compressional phase acting during upper Pliocene/lower Pleistocene (Argnani & Trincardi, 1988, 1993) caused localized inversion of basins, as in the Paola Basin.…”

A New Method for Seismically Safe Managing of Seismotectonic Deformations in Fault Zones

“…Traditionally, the term "fluids" include liquids and gases that fill void spaces arising from deformation in rock masses. Fluids are also magmatic melts, which themselves are sources of hydrothermal fluids ascending to the earth's surface through conducting faults [21]. The migration of fluid solutions affects the shear resistance of the faults through the lubrication and hydraulic effects on the walls of the fractured rock.…”

Finite volume modeling of bathymetry and fault-controlled fluid circulation in the Sea of Marmara

“…There are numerous Computational Fluid Dynamics (CFD) solvers such as Ansys-Fluent, Feflow, Visual Modflow, Comsol Multiphysics which can be used to perform numerical simulations in solving heat and fluid flow problems in earth sciences (Sarkar et al, 2002;MacKenna and Blackwell, 2004;Üner and Doğan, 2019;Loreto et al, 2019). Among them, finite volume based on the CFD Ansys-Fluent program was selected in this study, since it is capable of solving simultaneous equations of mass, momentum and energy conservations.…”

“…Therefore, high-permeability values are assigned to fault zones in our models. Heat and fluid flow properties which are presented in Table (1) and ( 2) are taken from these previous studies (McKenna and Blackwell 2004;Magri et al, 2010;Loreto et al, 2019;Üner and Düşünür Doğan 2021).…”

“…Table of physical parameters for geological units taken from previous studies (McKenna and Blackwell 2004;Magri et al 2010;Loreto et al 2019;Üner and Düşünür Doğan 2021) …”