RT Journal Article
T1 The Variscan gabbros from the Spanish Central System: A case for crustal recycling inthe sub-continental lithospheric mantle?
A1 Orejana García, David
A1 Villaseca González, Carlos
A1 Pérez-Soba Aguilar, Cecilia
A1 López García, José Ángel
A1 Billstrom, Kjell
AB The gabbroic intrusions that crop out along the Spanish Central System (SCS) are geochemicallyheterogeneous, including primitive and evolved rocks. Differentiation is mainly related to fractionation ofCr-spinel and olivine, but mixing with coeval granitic magmas or crustal assimilation may have also played arole in the evolution of the most differentiated rocks. The most primitive uncontaminated gabbros show arcliketrace element chondrite and primitive-mantle normalised patterns, characterised by large ion lithophileelements (LILE)-light rare earth elements (LREE) enrichment, Sr and Pb positive and Nb–Ta–Ti negativeanomalies. However, paleogeographic constraints suggest that the SCS was located far from subductionzones, so these geochemical signatures could be better explained by a recycling of continental crustalcomponents within the mantle. The most primitive SCS gabbros expand the Sr–Nd isotopic compositionalrange of the Variscan basic magmatism in the Central Iberian Zone to more depleted values. This reflects aheterogeneous sub-continental lithospheric mantle under central Spain ranging from a depleted mantle(εNd=+3.1, 87Sr/86Sr=0.704) towards an isotopically enriched component (εNd=−1.6, 87Sr/86Sr=0.706). Geochemical modelling suggests that mantle enrichment could be explained by minor lowercrustal metapelitic granulite contamination (~2%). Additionally, the Sr–Nd–Pb isotopic ratios of the mostprimitive gabbros match the composition of the European subcontinental lithospheric mantle recorded inultramafic xenoliths from western and central Europe.
PB Elsevier Science B.V., Amsterdam
SN 0024-4937
YR 2009
FD 2009
LK https://hdl.handle.net/20.500.14352/49588
UL https://hdl.handle.net/20.500.14352/49588
LA eng
DS Docta Complutense
RD 16 may 2024