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Published December 1, 1989 | public
Journal Article

Constrained reference mantle model


A dataset of updated normal mode eigenperiods is used to develop a new average upper mantle model. The starting model takes account of recent body wave and surface wave models and of constraints derived from different petrological models. Different parameterizations with or without anisotropy down to different depths are checked. Anisotropy seems to be required at least down to 200 km and preferably down to 400 km but with a smaller amplitude than in the preliminary reference Earth model (PREM). The new models provide velocity gradients down to 400 km in good agreement with finite strain trajectories. The S-wave velocity jump at 400 km is smaller than previously found from regional studies. If the S-wave and P-wave velocity jumps at the 400-km discontinuity are considered simultaneously, this discontinuity cannot be explained by an upper mantle composed mainly of olivine.

Additional Information

© 1989 Elsevier Science Publishers B.V. Received December l, 1988; revision accepted April 30, 1989. We thank Barbara Romanowicz and Genevieve Roult who gave us their eigenperiod data obtained from the GEOSCOPE network and Freeman Gilbert who made available average IGPP data, Contribution No. 1034. This research was supported by the National Science Foundation grants EAR-8317623. Contribution No. 4593, Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125 (U.S.A.)

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