Blueschists in Corsica represent a continuation of the internal Alpine Penninic Zone schistes lustrés nappe, metamorphosed during the Eoalpine (late Cretaceous) collision of a Tethyan subduction complex with the European continental plate. Although extremely complex, the Corsican schistes lustrés preserve some semblance of a coherent stratigraphy and have been divided into several units, the most important of which are the Castagniccia, Inzecca, and Santo Pietro Groups. The metasedimentary and ophiolitic rocks associated with the Inzecca and Castagniccia Groups have been correlated with similar Liguro-Piemontais units in the Western Alps and interpreted as representing Tethyan oceanic basement and cover. The nature of the basement to the Santo Pietro Group is, however, more controversial and could be oceanic, continental or both. The Corsican blueschists have suffered syn-metamorphic polyphase folding and thrusting, generally externally (WNW) directed, although SSW-directed nappe displacement has been described in western Cap Corse. The onset of high-pressure metamorphism is at least mid-Cretaceous in age, but a spread of younger radiometric dates has led authors to suggest that blueschist metamorphism has continued through the late Cretaceous and even into the Eocene, when the Adria microplate collided with Corsica. The highest metamorphic grades are recorded by undated eclogite relics which are overprinted by a pervasive blueschist metamorphism. The highest blueschist pressures are recorded along the eastern margin of Alpine Corsica. A later phase of (late Eocene?) SE-verging folding and backthrusting occurred under greenschist facies conditions. Late (post-Miocene) upright folding about N-S axes has greatly influenced the present outcrop pattern. Most recent work on these blueschists has concentrated on Cap Corse in NE Corsica where several nappes have been identified. Two of these, the Ersa-Centuri and Farinole Nappes, have been correlated with Austro-Alpine basement, with the Ersa-Centuri nappe being emplaced from the west. Various tectonic models have attempted to refine the ’Eoalpine obduction’ model, but there remains considerable disagreement over the timing of individual tectonometamorphic events. There is as yet no record of blue-schist metamorphism having occurred prior to the involvement of the European continental basement, the upper part of which has also suffered blueschist metamorphism. An analogy with these Eoalpine events is provided by the present-day collision of Australia with the Banda Arc.

The Adria microplate has been thrust westward onto the Corsican microplate by a distance of at least 150 km. This crustal duplication followed the Late Cretaceous easterly directed subduction of the eastern Corsican continental margin after consumption of intervening Tethyan oceanic crust. The suture zone separating the two micro-plates is delineated by the ophiolite-bearing Schistes lustrés nappe, which suffered a Late Cretaceous HP-LT metamorphism. The Corsican blueschists crystallised during a major thrusting event at depths probably in excess of 35 km, and were overprinted by post-tectonic greenschist facies assemblages at 15-20 km during Late Eocene times. Eventual uplift and exposure of the Schistes lustrés and ophiolites were probably the result of isostatic compensation and erosion during and following their emplacement onto continental basement. It is proposed that the major thrusting event occurred within a subducted oceanic portion of the Corsican microplate, in the footwall of a leading, overriding oceanic portion of the Adria microplate. Thrusts probably propagated in a dominantly piggyback sequence within the subducted oceanic slab, first involving the most deeply buried rocks, then progressively the less deeply buried rocks. This is evident from the fact that the ophiolites and Schistes lustrés that preserve the highest metamorphic "grade" are the most easterly, and structurally highest. The model deduced for emplacement of the Corsican ophiolite nappe may be applicable to the Schistes lustrés nappe that forms a major tectonic unit in the internal zones of the western Alps, and to the metamorphic ophiolite-bearing nappes in western Liguria.