In spite of the general acceptance of subduction in con- trolling the tectonic and magmatic evolution of the Central Mediterranean and the Apennines (FACCENNA et alii, 2004 and references therein; BECCALUVA et alii, 2004 for a review), several problems may be cited that are difficult to reconcile with arc-related models. These include: 1) incon- sistency between the along-strike length of the Benioff plane (about 200 km) off shore of Calabria and the length of the Apennine-Magrhebian system (about 3500 km from northern Liguria to the Gibraltar arc), 2) lack of typical accretionary prism geometries, 3) rheological difficulties involved in subducting the Adriatic continental lithosphere, 4) poor definition of tomographically-imaged slabs along peninsular Italy, 5) scarcity in peninsular Italy of calc-alka- line-rocks, 7) presence of rocks similar to those in rift- related settings (leucitites, carbonatites, kamafugites), 8) absence of isotopic end-members found in present-day, subduction-related magmas and presence of plume-related isotopic end-members (BELL et alii, 2004). The broad trends of the isotopic ratio patterns in the Paleogene to Quaternary Italian igneous rocks ( 87 Sr/ 86 Sr, δ 18 O, δ 13 C, 143 Nd/ 144 Nd, 206 Pb/ 204 Pb ratios) are adequately explained by three distinct end-members: EM1 (Enriched Mantle 1), FOZO (Focus Zone) and ITEM (ITalian Enriched Mantle) (BELL et alii, 2003). EM1 and FOZO are isotopic components recognized in oceanic basalts and FOZO reflects a plume-related, deep-seated, and perhaps more primitive component than any of the others (BELL & TILTON, 2003 and references therein). ITEM is a very enriched component from a source with moderately high U/Pb and Th/Pb, very high Rb/Sr, and low Sm/Nd time- integrated ratios; it has been found in Italian carbon- atites, leucitites and lamprophyres which are rocks not found in many active subduction zones. ITEM cannot be continental crust, because many of the rocks with this signature are undersaturated with respect to silica and have high Mg numbers. It might be mantle metasoma- tized by fluids from an old subducted continental crust, or a deep mantle signature possibly derived from a reser- voir sited at the D’’ core-mantle boundary layer and iso- lated from mantle convection. The isotopic signatures of the Italian lavas and the peculiar chemical compositions (e.g, ultra-alkaline rocks) Rend. Soc. Geol. It., 1 (2005), Nuova Serie, 111-112, 1 f. The Mediterraean region, an independent micro-plate above a trapped plume head: inferences from isotopic data and areal balance considerations GIUSY LAVECCHIA (*), KEITH BELL (**), FRANCESCO STOPPA (*) & NICOLA CREATI (*) (*) Dipartimento di Scienze della Terra, Università «G. D’Annun- zio», Campus Universitario Madonna delle Piane, 66013 Chieti Scalo, Italy. Tel. 0871/3556414; Fax 0871/3556454; glavecchia@unich.it (**) Ottawa-Carleton Geoscience Centre, Department of Earth Sciences, Carleton University, Ottawa, Ontario K1S 5B6, Canada. Fig. 1 - a) Boundaries of the Mediterranean microplate. b) Simple areal balance of an interpretative, upper mantle scale, transect across the Mediterranean (trace of the section in fig. 1a) showing a mantle plume trapped in the transition zone (TZ) (after LAVECCHIA & CREATI, 2005). The geometry of the plume head is largely hypo- thetical and is based on figure 6 in Brunet and Yuen (2000); the size of the plume is derived from the areal balance considerations. Key: b’= pre-Mediterranean rifting geometry b’’= present day geometry.