Hidden geological process beneath Europe could reshape understanding of plate tectonics
Scientists have discovered evidence of slow-motion lithospheric dripping—where chunks of Earth's crust sink into the mantle—beneath Europe's rift valleys. The finding reshapes how geologists model continental stability and could improve predictions of volcanic activity and seismic risk in economically vital regions.
Originaltitel: Enigmatic doublets at the 410-km discontinuity evidence for drip tectonics?
<p>We investigate the 410 km discontinuity (thereafter the '410') beneath Europe using teleseismic S-to-P converted waves. This discontinuity-associated with the olivine-wadsleyite phase transition at the top of the mantle transition zone (MTZ)-is widely used as an indicator of thermal variations linked to mantle upwellings and subducting slabs. Our results reveal complex structures of the '410', including closely spaced discontinuities above and below 410 km depth, within laterally confined regions (similar to 100-200 km wide). These features are predominantly aligned along a corridor extending from the western Alpine front (Western Alps, Rhone Graben) through the Eifel volcanic fields and the Eger Graben to the eastern Alpine front (Western Carpathians, northern Pannonian Basin, Eastern Carpathians), along the European Cenozoic Rift System (ECRIS). In several locations, the disturbed '410' is associated with an elevated lithosphere-asthenosphere boundary, suggesting a link between lithospheric processes and MTZ structure. We interpret these observations as evidence for small-scale lithospheric dripping, potentially initiated during or following the Alpine orogenesis. Additional occurrences of apparent '410' doubling are identified beneath the southern Scandes and the northern Adriatic region; beneath the Scandes, this feature spatially correlates with extensional tectonics. Overall, our results indicate that the '410' beneath Europe is strongly influenced by smaller-scale mantle dynamics, closely related to the ECRIS, rather than reflecting solely large-scale thermal anomalies.</p>