A late Oligocene suprasubduction setting in the westernmost Mediterranean revealed by intrusive pyroxenite dikes in the Ronda Peridotite (Southern Spain)

Claudio Marchesi*, Carlos J. Garrido, Delphine Bosch, Jean Louis Bodinier, Karoly Hidas, Jose Alberto Padron-Navarta, Fernando Gervilla

*Corresponding author for this work

Research output: Contribution to journalArticle

32 Citations (Scopus)

Abstract

Contrasting tectonic reconstructions of the westernmost Mediterranean have been proposed to explain the origin of the Alboran marine basin contemporaneously with Cenozoic convergence between the African and European plates. Cr-rich pyroxenites in the Ronda massif record the geochemical processes occurring in the subcontinental mantle of the Alboran domain in the Late Oligocene, thus constraining the geodynamic scenario of Cenozoic extension in the western Mediterranean lithosphere. Clinopyroxene in intrusive Cr-rich websterite dikes crosscutting the Ronda peridotite is strongly depleted in Nb-Ta and enriched in light rare earth elements, as typically observed in arc magmas, and is in trace element equilibrium with Neogene subduction-related lavas from the western and central Mediterranean. Sr-Nd-Pb radiogenic isotopes indicate that the mantle source of the Ronda pyroxenite dikes was contaminated by a subduction component released by detrital sediments likely deposited in passive continental margins. Rather than convective removal or delamination of the lithospheric root, our data strongly support Alboran geodynamic models that envisage slab rollback as the tectonic mechanism responsible for the Miocene lithospheric thinning. The Ronda Cr-rich pyroxenite dikes represent the earliest unambiguous manifestation of subduction-related magmatism in the western Mediterranean and testify to the involvement of terrigenous sediments in the primitive stages of subduction.

Original languageEnglish
Pages (from-to)237-247
Number of pages11
JournalJournal of Geology
Volume120
Issue number2
DOIs
Publication statusPublished - Mar 2012
Externally publishedYes

Keywords

  • POROUS MELT FLOW
  • TRACE-ELEMENT
  • BENI-BOUSERA
  • SUBCONTINENTAL LITHOSPHERE
  • RECRYSTALLIZATION FRONT
  • ISOTOPE SYSTEMATICS
  • MANTLE LITHOSPHERE
  • GARNET PYROXENITES
  • ALBORAN DOMAIN
  • GIBRALTAR ARC

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