Crustal Structure of the Ionian Basin and Eastern Sicily Margin: Results From a Wide‐Angle Seismic Survey

• Published in: Journal of Geophysical Research 2018-03, Vol.123 (3), p.2090-2114
• Main Authors: Dellong, David, Klingelhoefer, Frauke, Kopp, Heidrun, Graindorge, David, Margheriti, Lucia, Moretti, Milena, Murphy, Shane, Gutscher, Marc‐Andre
• Format: Article
• Language: English
• Subjects: Back propagation; Basins; Cruises; Crustal structure; Data acquisition; Earth Sciences; Escarpments; Fault lines; geodynamic; Geophysics; Ionian basin; Malta Escarpment; Mediterranean; Modelling; Oceanic crust; Oceanography; Paleoceanography; Paleontology; Plates (structural members); Rifting; Sciences of the Universe; Sedimentary basins; Seismic data; Seismic surveys; Seismic velocities; Seismic wave velocities; Seismological data; Subduction; Subduction (geology); Subduction zones; Surveying; Tearing; Tectonics; Velocity; Volcanology; Wave velocity; wide‐angle seismic
• ISSN: 2169-9313; 0148-0227; 2169-9356; 2156-2202
• DOI: 10.1002/2017JB015312

In the Ionian Sea (central Mediterranean) the slow convergence between Africa and Eurasia results in the formation of a narrow subduction zone. The nature of the crust of the subducting plate remains debated and could represent the last remnants of the Neo‐Tethys ocean. The origin of the Ionian basin is also under discussion, especially concerning the rifting mechanisms as the Malta Escarpment could represent a remnant of this opening. This subduction retreats toward the south‐east (motion occurring since the last 35 Ma) but is confined to the narrow Ionian basin. A major lateral slab tear fault is required to accommodate the slab roll‐back. This fault is thought to propagate along the eastern Sicily margin but its precise location remains controversial. This study focuses on the deep crustal structure of the eastern Sicily margin and the Malta Escarpment. We present two two‐dimensional P wave velocity models obtained from forward modeling of wide‐angle seismic data acquired onboard the R/V Meteor during the DIONYSUS cruise in 2014. The results image an oceanic crust within the Ionian basin as well as the deep structure of the Malta Escarpment, which presents characteristics of a transform margin. A deep and asymmetrical sedimentary basin is imaged south of the Messina strait and seems to have opened between the Calabrian and Peloritan continental terranes. The interpretation of the velocity models suggests that the tear fault is located east of the Malta Escarpment, along the Alfeo fault system. Key Points We image a two‐layered thin crust within the Ionian basin that we interpreted to be of probable oceanic origin The deep structure of the Malta Escarpment shows an abrupt crustal thinning zone that is interpreted to result from a transform origin of the margin The major tear fault accommodating the slab roll back of the subduction along the eastern Sicily margin was located along the Alfeo‐Fault System