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The basement of the Alpine Upper Danubian/Balkan nappe, dismembered between Romania, Serbia and Bulgaria, contains evidence of the Variscan orogenic evolution (Lower Devonian Balkan–Carpathian ophiolite, Carboniferous granites). Our study presents a new tectono-metamorphic interpretation of this basement and documents two main deformation phases, D1 and D2. D1 is a right-lateral thrust recorded in the metagabbroic rocks at the base of the ophiolitic nappe that also affects the underlying units. This phase is related to the ophiolite emplacement on a northerly margin with a top-to-the-palaeo-WNW (Variscan coordinates) at c. 360 Ma. D2 records a collisional event in a sinistral transpressive regime. In a zone of sheared folds, it juxtaposed low- (Eşelniţa metasediments) to high-grade metamorphic rocks (Corbu rocks: 600°C/ 5.2 kbar). Syntectonic granitic intrusions later heated these rocks locally before their final cooling, still during the D2 phase, and with localized circulation of fluids. The sinistral transpressive regime would prevail after the docking of the Balkans and the Sredna Gora terranes separating the Balkan–Carpathian oceanic basin and could correspond to left-lateral escape due to large-scale readjustments between both terranes during the Carboniferous. The Upper Danubian/Balkan basement appears to be located more northerly in the Variscan Belt than the other intra-Alpine basements (Getic, Western Carpathians, Eastern Alps, Western Alps).

The contact zone between two major allochthonous lithotectonic units in the French Massif Central (FMC) is characterized by the presence of corundum-bearing amphibolites associated with serpentinites, flaser-gabbros, eclogites and granulites. These unusual amphibolites are best preserved in the Western FMC, where they are found within the lower oceanic crust of the Limousin ophiolite. Mineralogical observations and thermodynamic modelling of the spinel-corundum-sapphirine-kyanite amphibolites in the CMASH system show that they were formed at peak P-T conditions around 800°C ⁄ 10 kbar in response to near isothermal burial followed by a retrogressive anticlockwise path. Metamorphic reactions are controlled both by modification of P-T conditions and by local chemical changes linked to fluid infiltration. Pargasite growth has been enhanced by infiltration of Ca-and Al-rich fluids whereas kyanite-and sapphirine-forming reactions are partly controlled by local inputs of MgO-SiO 2 components, most probably during infiltration metasomatism. By analogy with worldwide ophiolites (Oman, Tethyan, Appalachian) and published numerical models, subduction of a still-hot oceanic ridge is proposed to form these Al-rich amphibolites from plagioclase-rich troctolites. The trace-element composition of high-Ti, fine-grained amphibolites (former fine-grained Fe-Ti gabbros) adjacent to the corundum-bearing ones, further indicates that the oceanic crust was initially created at a mid-ocean ridge (rather than within a back-arc basin), followed by the emplacement of supra-subduction zone-type magmas, probably due to intraoceanic subduction close to the ridge.

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