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RESEARCH PRODUCT

Temporal–spatial evolution of low-SiO2 volcanism in the Pleistocene West Eifel volcanic field (West Germany) and relationship to upwelling asthenosphere

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Abstract The temporal–spatial evolution of low-SiO 2 lavas from the Pleistocene West Eifel volcanic field (Central European Volcanic Province) and linked petrogenetic variations are evaluated using 40 Ar/ 39 Ar age and geochemical data. Geochronological and petrological evidence is related to the physical structure of the previously established seismologically anomalous asthenosphere interpreted as thermally upwelling mantle (Eifel Plume). Lava flows >480 ka (Middle Pleistocene) occur exclusively in the NW of the volcanic field. After a time span of ca. 400 ka lacking significant activity, volcanism has migrated to the SE generating flows At melting depth >70 km of parental asthenospheric melts in garnet–spinel peridotite the surface-projected contour of the low-velocity P -wave anomaly coincides with the geographical boundary separating >480 ka volcanism in the NW from 480 ka volcanism reside within and beyond the P -wave velocity anomaly, respectively. The coupling between time-space pattern of volcanism and seismological contrast in the mantle sources indicates that volcanic activity is linked to a highly dynamic low-velocity anomaly with lateral and vertical motion rates of 4–5 cm/year and up to 6 cm/year, respectively. The change in seismological contrast is accompanied by a transition in the petrogenetic style resulting from differently intense thermal erosion of multiply metasomatized lithosphere by upwelling asthenosphere. Asthenosphere-lithosphere interaction is widespread in the NW and subordinate in the SE of the volcanic field, where melts ascended through a more refractory lithosphere which has been affected by preferential melting of hydrous portions by pre-80 ka thermal exposure.