Tomographic consistency in imaging lower-mantle plumes and their link to European Cenozoic Rift Volcanism

A wide northeast-trending belt of intraplate alkaline volcanism, exhibiting similar geochemical characteristics, stretches from the Eastern Atlantic Ocean to the Cenozoic rift system in Europe. Its formation is associated with both passive and active mechanisms, but it remains a source of ongoing debate among geoscientists. Here, we show that seismic whole-mantle tomography models consistently identify two extensive low-velocity anomalies beneath the Canary Islands (CEAA) and Western-Central Europe (ECRA) at mid-mantle depths, merging near the core-mantle boundary. These low-velocity features are interpreted as two connected broad plumes originating from the top of the African LLSVP, likely feeding diapir-like upwellings in the upper mantle. The CEAA rises vertically, whereas the ECRA is tilted and dissipates at mantle transition zone depths, possibly due to the interaction with the cold Alpine subducted slab, which hinders its continuity at shallower depths. While plate-boundary forces are considered the primary drivers of rifting, the hypothesis that deep mantle plumes play a role in generating volcanic activity provides a compelling explanation for the European rift-related alkaline volcanism, supported by geological, geophysical, and geochemical evidence.