Figure 1

The Tyrrhenian Sea. Shaded relief image derived from bathymetric data with sun illumination from NE, 45° over the horizon and no vertical exaggeration (grid resolution 100 m). Mercator projection at 40° N. Bathymetry of the Tyrrhenian region was obtained by merging all the available multibeam^48,49,50 and EMODnet gridded data (http://www.emodnet.eu/bathymetry). The multibeam data were processed by the Kongsberg Neptune/Poseidon packages; spatial analysis and mapping were performed using the GMT⁵¹ and PLOTMAP⁵² packages. Coastline from different map sources at scale 1:100,000.0 published by Istituto Idrografico della Marina was digitized in geographical coordinates by using the software DIGMAP⁵³ and were converted to the WGS84 geodetic datum by the program DATUM⁵⁴. Filled red circles indicate the DSDP 373 and ODP 650 sites that penetrated basaltic crust of Late Miocene (L-M) and Latemost Pliocene (Lm-P) age in the Vavilov and Marsili plains (VP and MP, respectively). Such early oceanization episodes were followed by episodes characterized by the emplacement of corresponding homonymous large central volcanoes. Black arrows indicate the direction of the L-M and Lm-P hyperextension pulses trending E-W and NW-SE, respectively. Besides ODP-Site-650, volcanic manifestations of Lm-P age are found also offshore from Sardinia (ODP-Site-654), and on Palmarola island (see text). Mg = Magnaghi volcano.