Ionian Abyssal Plain: A window into the Tethys oceanic lithosphere

Abstract

The nature of the Ionian Sea crust has been the subject of scientific debate for more than 30 years, mainly because seismic imaging of the deep crust and upper mantle of the Ionian Abyssal Plain (IAP) has not been conclusive to date. The IAP is sandwiched between the Calabrian and Hellenic subduction zones in the central Mediterranean. To univocally confirm the proposed oceanic nature of the IAP crust as a remnant of the Tethys ocean and to confute its interpretation as a strongly thinned part of the African continental crust, a NE-SW oriented 131 km long seismic refraction and wide-angle reflection 15 profile consisting of eight ocean bottom seismometers and hydrophones was acquired in 2014. A P-wave velocity model developed from travel time forward modelling is refined by gravimetric data and synthetic modelling of the seismic data. A roughly 6 km thick crust with velocities ranging from 5.1 km/s to 7.2 km/s, top to bottom, can be traced throughout the IAP.In the vicinity of the Medina Seamounts at the southern IAP boundary, the crust thickens to about 9 km and seismic velocities decrease to 6.8 km/s at the crust-mantle boundary. The seismic velocity distribution and depth of the crust-mantle boundary 20 in the IAP document its oceanic nature, and support the interpretation of the IAP as a remnant of the Tethys oceanic lithosphere formed during the Permian and Triassic period.

Faulting, sediment loading, and flow of underlying ductile units: A case study from the Western Ionian Basin Offshore Eastern Sicily

“…The Ionian Basin is a remnant of a Mesozoic oceanic domain connected to the Permo-Triassic opening of the Neo-Tethys Ocean (Şengör, 1979), and it is considered the oldest sea rooted by an "in situ" oceanic crust (Speranza et al, 2012;Dannowski et al, 2019). The Ionian oceanic lithosphere began to subduct beneath the European margin 35 Ma ago (Malinverno & Ryan, 1986;Jolivet & Faccenna, 2000).…”