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Rare Earth and 3d Transition Element Geochemistry of Peridotitic Rocks: II. Ligurian Peridotites and Associated Basalts |
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| Authors: | OTTONELLO G; JORON J L; PICCARDO G B |
| Institution: | 1Istituto di Geocronologia e Geochimica Isotopica del C.N.R., Via Cardinale Maffi 36, 56100 Pisa, Italy 2Laboratoire par analyse en activation neutronique Pierre Süe, C.E.A. Saclay, and Institute de Physique du Globe, Université de Paris VI Place Jussieu, Paris, France 3Istituto di Mineralogia, Petrografia e Geochimica, Via La Pira, 4, 50121 Firenze, Italy |
| Abstract: | Peridotites and associated basalts of the External (EL) andInternal (IL) Ligurian terrains of the Northern Apennines havebeen investigated geochemically. The REE and 3d transition elementcompositions of IL peridotites reflect partial fusion of a spinelperidotite protolith probably in the spinel-plagioclase transitionzone. EL peridotites underwent only incipient melting underclosed system conditions. Basalts associated with EL and ILperidotites have petrography and chemistry akin to MORB. Basedon REE, they can be regarded as the products of fractional melting(IL to some extent at higher F with respect to EL). PositiveEu anomalies in most of the studied IL basalts are due to plagioclasefractional crystallization; also, on the basis of Sc, Co, Nicompositions, fractional crystallization of olivine can be recognizedfor both EL and IL lavas. IL basalts are possibly cogeneticwith IL peridotites, but the same cannot be said for EL lavas. |
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