Joint geodynamical and seismic modelling of the Eifel plume

Abstract

S U M M A R YTeleseismic P-wave tomography has revealed a columnar low-velocity anomaly in the upper mantle below the volcanic Eifel region in western Germany extending to at least 400 km depth.Here we explore whether a geodynamically consistent model of a mantle plume can explain the observed traveltime residuals. We use a 3-D mantle convection code with temperature and pressure-dependent viscosity to generate a suite of model plumes that rise from the transition zone and spread below a stationary or drifting lithospheric plate. We use ray tracing to calculate synthetic travel times and vary the plume location, radius, temperature and the rate and direction of plate motion in order to fit the observed travel times. Our results show a fair correlation between synthetic and observed traveltime residuals. The presence of additional structures in the lithosphere and upper mantle of the Eifel region that are not covered by a simple plume model prevents a perfect fit of the observed seismological data and may bias to some degree the derived plume parameters. The traveltime anomalies are mainly caused by the plume stem with smaller contributions from the plume head. Models with and without an axisymetric plume head below the lithosphere fit the data almost equally well and we conclude that the absence of a plume head in tomographic images does not rule out its existence. In the best-fitting model the plume stem has a radius of 60 km and rises about 50 km to the SW of the quaternary volcanic field below a lithosphere that this slowly moving in the NNE direction. The temperature of the plume and its flux cannot be constrained tightly from our model results, but combining them with other constraints we estimate an excess temperature of ∼200 • C and a buoyancy flux of 500-1000 kg s −1 .

Temperature of the plume layer beneath the Yellowstone hotspot

“…These values defi ne a buoyancy fl ux estimate of 0.03-0.1 Mg/s for a plume excess temperature of 70-200 °C, consistent with estimates from other methods (Waite, 2004). This buoyancy fl ux is much smaller than the 8 Mg/s buoyancy fl ux estimated for the Hawaiian plume (Sleep, 1990), but close to the 0.5-1.0 Mg/s fl ux proposed for the Eifel plume (Wüllner et al, 2006). The excess temperature found by our analysis, combined with the tomographic and mantle velocity discontinuity results (Fee and Dueker, 2004;Waite et al, 2006;Yuan and Dueker, 2005), strongly suggests that the ultimate cause of the Yellowstone hotspot track is a thermal mantle plume.…”

Absolute plate motions constrained by shear wave splitting orientations with implications for hot spot motions and mantle flow

“…However, an opposite HS would not, by itself, predict a plume that is more consistent with flow predictions. Although APM is very different from previous estimates (and, if wrong, could be the cause of the anomalous plume ), independent evidence of shallow, APM‐controlled, tilting of the Eifel plume toward the NNE [ Wüllner et al , 2006] suggests that GSRM‐APM‐1 properly describes APM in Europe (albeit some mm/a slower than Wüllner et al [2006] found).…”

Seismological and Geophysical Signatures of the Deep Crustal Magma Systems of the Cenozoic Volcanic Fields Beneath the Eifel, Germany

“…The v s anomaly is absent between 170 and 240 km depth and has a large E‐W extension below. The anomalous low v P beneath the West Eifel can be explained by 200°C excess temperatures in the upper mantle up to 1200–1300°C, a few percent of partial melts (Ritter, 2007), and a buoyancy flux of 500–1,000 kg/s (Wüllner et al, 2006). The measured heat flux in the WEVF of 70–80 mW/m 2 is lower than expected from a deep mantle plume assuming steady‐state conductive heat transfer, indicating that the thermal perturbation beneath the Eifel is possibly small (Seck & Wedepohl, 1983).…”

“…The Quaternary WEVF and EEVF occur above a 100 km broad seismic S wave anomaly in the upper mantle and a broader region of Moho upwelling as documented by receiver functions (Figure 1). Therefore, a plume‐like upwelling of asthenospheric and lithospheric mantle rocks has been suggested (Ritter et al, 2001), which may possibly have even deeper roots in a lower mantle plume with a stem radius of 60 km and a center about 50 km to the S of the WEVF and 80 km S‐SW of the EEVF (Ritter, 2007; Wüllner et al, 2006).…”