%0 Journal Article
%A Villaseca González, Carlos
%A Ancochea Soto, Eumenio
%A Orejana García, David
%A Jeffries, Teresa E.
%T Composition and evolution of the lithospheric mantle in centralSpain: inferences from peridotite xenoliths from theCenozoic Calatrava volcanic field
%D 2010
%@ 0305-8719
%U https://hdl.handle.net/20.500.14352/41912
%X Spinel lherzolite xenoliths from the Cenozoic Calatrava volcanic field provide asampling of the lithospheric mantle of central Spain. The xenoliths are estimated to originatefrom depths of 35–50 km. Trace element content of clinopyroxene and Cr-number in spinel indicatelow degrees of partial melting (5%) of the xenoliths. Although a major element whole-rockmodel suggests wider degrees of melting, the Calatrava peridotite chemistry indicates a moderatelyfertile mantle beneath central Spain. Calatrava peridotite xenoliths bear evidence for interactionwith two different metasomatic agents. The enrichment in LREE (light rare earth element), Th,U and Pb, and the negative anomalies in Nb–Ta in clinopyroxene and amphibole from xenolithsof El Aprisco, indicate that the metasomatic agent was probably a subduction-related melt, whereasthe enrichment in MREE in clinopyroxene from xenoliths of the Cerro Pelado centre suggests analkaline melt similar to the host undersaturated magmas. These metasomatic agents are also consistentwith the chemistry of interstitial glasses found in xenoliths of the two volcanic centres.Differences in metasomatism but also in mantle composition is supported by Sr–Nd whole-rockdata, which show a more radiogenic nature for Sr isotopes of samples from the El Aprisco centre(87Sr/86Sr ratios of 0.7035–0.7044 instead of 0.7032–0.7037 for samples from Cerro Pelado).The timing of the subduction-related metasomatic stage is unconstrained, although the Calatravaintraplate volcanism intrudes an old Variscan lithospheric section reworked during the convergingplate system affecting SE Iberia in the Tertiary. The presence of wehrlite types within the Calatravaperidotite xenoliths is here interpreted as a reaction of host lherzolites with silica-undersaturatedsilicate melts that could be related to the Calatrava alkaline magmatism. The Sr–Nd isotopic compositionof Calatrava peridotites plot within the European asthenospheric reservoir (EAR) mantle,these values represent more enriched signatures than those found in the other Spanish Cenozoicalkaline province of Olot.
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