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Communication Dans Un Congrès Année : 2015

Subduction initiation, recycling of lower continental crust, and intracrustal emplacement of subcontinental lithospheric mantle in the westernmost Mediterranean

Résumé

The geochemistry of high-Mg pyroxenite dykes in the Ronda peridotite (S Spain) shows that the subcontinental lithospheric mantle in the westernmost Mediterranean evolved above a subducting slab shortly before its intracrustal emplacement. We present new SrNd-Pb isotopic data of crustal rocks in the western Betics that might account for the isotopic signature of Ronda high-Mg pyroxenite. We show that lower crustal garnet granulites from the Alpujarride complex, which overly the peridotites, account for the characteristic relatively high 207Pb-208Pb/204Pb and low 206Pb/204Pb subduction component of Ronda high-Mg pyroxenite. The involvement of fluids/melts derived from lower crust in the genesis of high-Mg Ronda pyroxenite indicates that the peridotites in the westernmost Mediterranean were placed in a forearc position above a newly initiated subduction zone, followed by underthrusting of the lower crust. This possibly occurred during the late Oligocene due to the inversion of an extensional back-arc continental basin. As subduction progressed, the thinned subcontinental mantle was emplaced over the foreland following its collision with the trench.
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Dates et versions

hal-03934253 , version 1 (11-01-2023)

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  • HAL Id : hal-03934253 , version 1

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María Isabel Varas-Reus, Carlos J. Garrido, Delphine Bosch, Claudio Marchesi, Károly Hidas, et al.. Subduction initiation, recycling of lower continental crust, and intracrustal emplacement of subcontinental lithospheric mantle in the westernmost Mediterranean. 2nd European Mantle Workshop 2015, MINERALOGICAL SOCIETY OF POLAND, Aug 2015, Wroclow, Poland. pp.91. ⟨hal-03934253⟩
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