Gravity observations in the western Rhenish Massif and forward modelling of the Eifel plume bouguer anomaly

Abstract

We study the gravity field of the western Rhenish Massif, Germany, to search for relationships to the mantle source of the recent Eifel volcanism. First we compile the available gravity data from the region and present them as Bouguer gravity map. This map does hardly show any anomaly univocally related to the Eifel plume, even after careful wavelength filtering the data. Forward modelling of the Bouguer gravity field with the seismological low-velocity anomaly in the upper mantle as input anomaly finds that the seismological model corresponds to an approximately -10 mGal anomaly (1 mGal is 10-5 m s-2). Such a tiny signal can be hardly recognized in the real data: Intrusions of magmatic high-density dykes and sills may even hide or reverse the expected negative mantle gravity signal which makes the situation even worse. As conclusion we find that a gravity signal of the Eifel plume cannot be seen in the available Bouguer data, but that this negative result is at least consistent with the seismological mantle models. Furthermore the forward modelling results suggest that small-scale upper mantle plumes may not be recognized as a Bouguer anomaly underneath a typical heterogeneous continental lithosphere. © 2007 Springer-Verlag Berlin Heidelberg.