Seminari di Scienze della Terra
Universita’ di Genova
11 Settembre 2006

 Multidisciplinar Approach to Natural Triggers of Lithosphere Evolution

Palinspastic reconstructions suggest that the Ligurian Tethys did not reach the size of modern oceans. In addition, age data indicate a narrow time span between the end of divergence and the onset of convergence and subduction. Oceanic accretion in the Ligurian Tethys started during Middle Jurassic and continued for approximately 25 Ma (cf. Winterer and Bosellini, 1981). In the Alpine realm, plate convergence leading to subduction of the oceanic lithosphere probably started during the Late Cretaceous. The subduction zone had a south-west trending, with the Europe plate underthrusting the Adria plate, and it was most probably intra-continental in the northern sector of the Western Alps, and progressively intra-oceanic towards the Ligurian sector.

Figure 1 - Mesozoic evolution of Central Atlantic and Ligurian Tethys oceans, from rifting to ocean formation (redrawn and modified after Lemoine et al., 1987). Figure 2 - Generalized paleogeographic restoration of the Ligurian Tethys, with location of the different Ligurian domains (redrawn and modified after Dal Piaz, 1995).

The Ligurian Tethys was completely closed in the Early Tertiary, when fragments of its oceanic lithosphere were emplaced as west-vergent thrust units in the Alps and east-vergent thrust units in the Apennine. Depending on their stratigraphic, structural and metamorphic characteristics, the different ophiolitic sequences of the Ligurian sector have been ascribed to different palaeogeographic settings in the Jurassic-Cretaceous Ligurian Tethys.



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