Abstract
Subduction-transform edge propagators are lithospheric tears bounding slabs and back-arc basins. The volcanism at these edges is enigmatic because it is lacking comprehensive geological and geophysical data. Here we present bathymetric, potential-field data, and direct observations of the seafloor on the 90 km long Palinuro volcanic chain overlapping the E-W striking tear of the roll-backing Ionian slab in Southern Tyrrhenian Sea. The volcanic chain includes arc-type central volcanoes and fissural, spreading-type centers emplaced along second-order shears. The volume of the volcanic chain is larger than that of the neighbor island-arc edifices and back-arc spreading center. Such large volume of magma is associated to an upwelling of the isotherms due to mantle melts upraising from the rear of the slab along the tear fault. The subduction-transform edge volcanism focuses localized spreading processes and its magnitude is underestimated. This volcanism characterizes the subduction settings associated to volcanic arcs and back-arc spreading centers.
Highlights
Subduction-transform edge propagators are lithospheric tears bounding slabs and back-arc basins
Many subduction zones including Tonga, New Hebrides, Lesser Antilles, South Sandwich, and Ionian Sea-Calabrian Arc are, affected by a still poorly known volcanism associated to lithospheric tear faults known as subduction-transform edge propagators (STEP)[5,6,7,8]
Only the Palinuro and Glabro seamounts were previously identified as volcanic edifices, whereas our new bathymetric data show that the Palinuro STEP includes a ~90 km long, ~20 km wide strip defined by 15, E-W aligned major volcanoes (Fig. 2a)
Summary
Subduction-transform edge propagators are lithospheric tears bounding slabs and back-arc basins. The volume of the volcanic chain is larger than that of the neighbor island-arc edifices and back-arc spreading center Such large volume of magma is associated to an upwelling of the isotherms due to mantle melts upraising from the rear of the slab along the tear fault. Many subduction zones including Tonga, New Hebrides, Lesser Antilles, South Sandwich, and Ionian Sea-Calabrian Arc are, affected by a still poorly known volcanism associated to lithospheric tear faults known as subduction-transform edge propagators (STEP)[5,6,7,8]. Two main tear faults delimit the western and northern boundaries of the Ionian slab[19, 20, 25]: a NNW–SSE striking, dextral strike-slip fault system (Tindari Letojianni fault, TL fault in Fig. 1a) crossing the central sector of the Aeolian island-arc, and an E-W striking STEP fault system (hereafter Palinuro STEP; Fig. 1a) along which the Palinuro and Glabro seamounts were emplaced between 0.8 and 0.3 Ma11. The results open new perspectives on the volcanism and geodynamics of back-arc subduction zones
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