The long-range seismic refraction experiment in the Rhenish Massif.

Abstract

This experiment to investigate the crust and uppermost mantle structure beneath the Rhenish massif included a 600 km long main profile extending from the Paris Basin in the SW, across the massif itself, to the Hessian depression in the NE, and three cross-profiles, up to 170 km long, almost wholly located in the massif itself. Interpretation of the data, including ray-tracing through laterally inhomogeneous media and calculation of synthetic seismograms, has yielded velocity-depth information. An attempt is made to explain the results obtained from the seismic experiment in terms of a petrological model. In particular, the transition zone from low velocities (6.3-7.0 km/s) to high velocities (8.4 km/s) in the depth range 30-35 km, along the main profile NE of shot-point D, may be explained in terms of magmatic material rising from greater depths and being trapped at the level of the crust-mantle boundary structure.-J.M.H.