Publication: Registro de eventos metasomáticos en los xenolitos peridotíticos del volcán de Los Tormos (Campo de Calatrava, España)
Loading...
Full text at PDC
Publication Date
2021
Advisors (or tutors)
Editors
Journal Title
Journal ISSN
Volume Title
Publisher
Sociedad Geológica de España.
Citations
Exportar
Abstract
En el volcán de Los Tormos (Campo de Calatrava) se han distinguido dos grupos principales de xenolitos mantélicos en función del análisis modal, presencia de anfíbol y composición química del clinopiroxeno, lo que permite deducir al menos dos sectores del manto ligados a eventos metasomáticos de diferente naturaleza. El grupo más abundante son lherzolitas con espinela, formados por minerales con contenidos altos de Mg, y clinopiroxeno con bajo contenido en elementos traza incompatibles y espectros normalizados relativamente planos, que evidenciaría afinidad con un manto empobrecido tipo MORB, el manto más primitivo del conjunto. Sin embargo, las anomalías negativas en Nb-Ta y enriquecimiento variable en los elementos más incompatibles (Th, U, Pb, tierras raras ligeras) y elementos móviles (Sr, K, Ba) en dichos espectros indicarían la interacción con fluidos metasomáticos derivados de zonas de ubducción, que actuarían con distinta intensidad. Las wehrlitas con anfíbol destacan por la riqueza en hierro de sus minerales, así como por la composición del clinopiroxeno, con espectros de elementos traza normalizados enriquecidos en los elementos medianamente incompatibles, todo lo cual sugiere el paso de fundidos metasomáticos de naturaleza silicatada alcalina rica en carbónico. Este mismo metasomatismo afectaría a algunos xenolitos lherzolíticos con espectros similares.
In xenoliths from the Los Tormos volcano (Calatrava volcanic field), two main mantle xenolithic groups have been distinguished according to modal analysis, amphibole occurrence and clinopyroxene chemical composition. These features suggest different origins for each xenolith group, evidencing mantle sectors metasomatized by different agents. The spinel-bearing lherzolite xenoliths define the most abundant group, showing high magnesium and low trace-element contents in the rock-forming minerals, with nearly flat clinopyroxene trace element pattern, suggesting affinity to depleted mantle sources (MORB type). The well-pronounced Nb-Ta negative anomaly in these patterns indicates later variable interaction with subduction-related metasomatic agents. The amphibole-bearing wehrlite group shows Fe-rich mineralogy and clinopyroxene normalized trace-element spectra enriched in the most incompatible elements, defining typical metasomatism by carbonate-rich silica under-saturated alkaline melt. The other xenoliths showing similar trace element patterns than hydrous wehrlites are also affected by silica-undersaturated alkaline metasomatism.
In xenoliths from the Los Tormos volcano (Calatrava volcanic field), two main mantle xenolithic groups have been distinguished according to modal analysis, amphibole occurrence and clinopyroxene chemical composition. These features suggest different origins for each xenolith group, evidencing mantle sectors metasomatized by different agents. The spinel-bearing lherzolite xenoliths define the most abundant group, showing high magnesium and low trace-element contents in the rock-forming minerals, with nearly flat clinopyroxene trace element pattern, suggesting affinity to depleted mantle sources (MORB type). The well-pronounced Nb-Ta negative anomaly in these patterns indicates later variable interaction with subduction-related metasomatic agents. The amphibole-bearing wehrlite group shows Fe-rich mineralogy and clinopyroxene normalized trace-element spectra enriched in the most incompatible elements, defining typical metasomatism by carbonate-rich silica under-saturated alkaline melt. The other xenoliths showing similar trace element patterns than hydrous wehrlites are also affected by silica-undersaturated alkaline metasomatism.