Eos, Transactions American Geophysical Union

Alfred Wegener Conference



From August 28–31, 1982, the Alfred Wegener-Stiftung held its 1st Alfred Wegener Conference on ‘Geophysical, Geochemical and Petrological Evidence on Deformation and Composition of the Continental Subcrustal Lithosphere’ at Seeheim/F.R. Germany. It was convened by K. Fuchs (University of Karlsruhe) and H. Wanke (Max-Planck-Institut Mainz).

The main results and questions from this conference may be summarized as follows: Geophysical, petrological, and geochemical models of the earth's continental lithosphere have been refined recently so far that they are no longer independent of one another. From an analysis of xenoliths the compositions proposed for this part of the earth were confronted with seismic velocities measured in situ at depth. Both observations are not compatible unless seismic anisotropy is present in the upper mantle. Triaxial anisotropy was also required in the asthenosphere from a world-wide inversion of surface wave data. Seismic anisotropy was recognized as a possible tracer of mantle convection. Whether it signifies a paleomotion or is generated by recent flow patterns depends on a number of material parameters that require future research in the field, in the laboratory, and in numerical modeling, e.g., experiments on stress relations at low strain rates, on seismic velocities and their partial derivatives at seismic frequencies under upper-mantle conditions, and on field experiments to map anisotropy in the mantle and lower crust. The conference showed that geophysical, petrological, and geochemical models can and should be integrated, since they offer mutual constraints.