The pre-oceanic evolution of the Erro-Tobbio peridotite (Voltri Massif, Ligurian Alps, Italy)

摘要: Abstract This paper presents the results of field, structural, petrologic and geochemical investigations on Erro-Tobbio (E-T) ophiolitic peridotite (Voltri Massif, Ligurian Alps, Italy). massif represents a mantle section equilibrated at spinel-facies conditions in subcontinental lithosphere Europe-Adria system prior to Early Jurassic that has been exhumed emplaced sea-floor during rifting opening an ocean basin. The E-T comprises km-scale volumes peridotites with structural compositional characteristics pointing melt–peridotite interaction. Their formation is thought result from interaction pristine lithospheric MORB-type melts ascending by porous flow, leading development reactive spinel harzburgites, impregnated plagioclase replacive dunites. melt-related events were followed MORB melt intrusion. Field relationships between sheared peridotites, including coarse tectonites as well fine-grained mylonites developed extension, melt-modified suggest processes occurred exhumation mantle. These likely included both diffuse percolation focused intrusion are considered be consequence MORB-forming partial melting asthenosphere induced near-adiabatic decompressional upwelling related extension thinning. Field, petrological data allow us conclude entire pre-oceanic evolution deformation, metamorphism magmatism recorded started Early-Middle was Late Tethys ocean.