Geodynamic Significance of Intraplate Basaltic Magmatism From the Western Mediterranean Region

Abstract

Dynamic topography changes as mantle convection evolves, making its past surface expression difficult to reconstruct. Widespread Neogene-Quaternary intraplate basaltic magmatism across the Western Mediterranean Region allows us to test whether dated basalts preserve the mantle thermal structure responsible for regional dynamic support. We combine major, trace, and rare earth element (REE) analyses and modeling from six volcanic provinces with calibrated earthquake tomographic models and residual topographic and bathymetric measurements. The geochemical data set includes both newly acquired and published analyses. Rare earth element inverse modeling of samples least affected by lithospheric-mantle influence indicates that melting occurred beneath lithosphere typically 60–70 km thick and at asthenospheric potential temperatures ranging from approximately ambient to 50°C above ambient mantle. These estimates agree with independent tomographic constraints. Dynamic support calculated from the inferred thermal structure is also consistent with measured residual anomalies. Lithospheric thinning accounts for most of the largest positive anomalies of approximately 0.5 km without requiring large asthenospheric temperature anomalies. The agreement demonstrates that Western Mediterranean intraplate basaltic magmatism records upper-mantle thermal structure capable of generating regional surface support and provides a basis for reconstructing past mantle conditions and transient dynamic topography from dated basalts.