Seismic Anisotropy of the Subcrustal Lithosphere in Europe: Another Clue to Recognition of Accreted Terranes?
- John W. Hillhouse
Published Online: 18 MAR 2013
Copyright 1989 by the American Geophysical Union
Deep Structure and Past Kinematics of Accreted Terranes
How to Cite
Babuška, V. and Plomerová, J. (1989) Seismic Anisotropy of the Subcrustal Lithosphere in Europe: Another Clue to Recognition of Accreted Terranes?, in Deep Structure and Past Kinematics of Accreted Terranes (ed J. W. Hillhouse), American Geophysical Union, Washington, D. C.. doi: 10.1029/GM050p0209
- Published Online: 18 MAR 2013
- Published Print: 1 JAN 1989
Print ISBN: 9780875904542
Online ISBN: 9781118666609
- Geology, Structural—Congresses;
P-wave residuals computed relative to a reference Earth model and normalized for effects originating in focal regions and along ray paths in the deep mantle provide information on deep lithospheric structure. The variations of the directionally independent representative average residuals, which are computed for waves arriving from different azimuths and with steep incidence angles, reflect compositional and thermal inhomogeneities. In our model they are attributed to variations of the lithosphere thickness. On the other hand, the variations of relative residuals that depend on the angles of azimuth and incidence form spatial patterns suggesting the existence of large-scale dipping anisotropic structures in the subcrustal lithosphere. The P-velocity anisotropy of these structures (9–11% on the average) agrees with the anisotropy of olivine ultramafites as measured in the laboratory. Orientations of the deep anisotropic structures change in the vicinity of important tectonic suture zones, for example, at the suture between the Saxothuringicum and Moldanubicum in central Europe, at the Insubric line in the Alps, and at the deep contact between the Rhodopean Massif and the Moesian Platform in the central Balkans. The structures probably retain preferred orientations of olivine crystals originating from an ancient oceanic lithosphere and may thus represent relict paleosubduction zones by which the continental lithosphere grew in the past.