Subduction-related metasomatism in the lithospheric mantle beneath the Calatrava volcanic field (central Spain): constraints from lherzolite xenoliths of the Cerro Gordo volcano

Two types of lherzolite xenoliths appear in the Cerro Gordo maar from the Cenozoic Calatrava volcanic field. Hydrous lherzolites (group-1) show a major proportion of metasomatic amphibole (>5 modal%), whereas group-2 lherzolites have only accessory amounts or an absence of amphibole. Group-1 lher...

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Published inInternational geology review Vol. 64; no. 4; pp. 469 - 488
Main Authors Villaseca, Carlos, García Serrano, Javier, Pérez-Soba, Cecilia
Format Journal Article
LanguageEnglish
Published Taylor & Francis 21.02.2022
Subjects
Calatrava volcanic field
Lherzolite xenoliths
secondary orthopyroxene
Si-rich glass
subduction-related metasomatism
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Summary:Two types of lherzolite xenoliths appear in the Cerro Gordo maar from the Cenozoic Calatrava volcanic field. Hydrous lherzolites (group-1) show a major proportion of metasomatic amphibole (>5 modal%), whereas group-2 lherzolites have only accessory amounts or an absence of amphibole. Group-1 lherzolites show a higher LREE-Ba-Sr-Th content in whole-rock composition compared to group-2 lherzolites. The most depleted group-2 lherzolite xenoliths indicate a low degree of partial melting (<5%) of the mantle source, similarly to other Calatrava xenolith suites. Trace element content combined with Sr-Nd isotopic ratios suggests a protolith mantle source with the characteristics of a depleted MORB Mantle (DMM type). This mantle protolith was later refertilized by subduction-related metasomatism, causing the formation of modal amphibole and obliterating the original MORB-like chemical features in the most transformed xenoliths (group-1 lherzolites). The entrainment of these mantle fragments in the volcanic alkaline magma promoted amphibole breakdown reactions during its transport, generating silica-rich glasses with the associated unusual formation of secondary orthopyroxene. The suprasubduction character of the protolithic mantle combined with previously published Re-Os model ages in nearby lherzolite xenoliths suggests that the sampled lherzolites could represent the old Cadomian mantle wedge of the Central Iberian zone.
ISSN:0020-6814
1938-2839
DOI:10.1080/00206814.2020.1858453