Seismic anisotropy and its geological implications on the Lofoten (Norway) continental shelf: Seismic anisotropy off Lofoten
Rolf Mjelde, 1996. "Seismic anisotropy and its geological implications on the Lofoten (Norway) continental shelf: Seismic anisotropy off Lofoten", Seismic Anisotropy, Erling Fjær, Rune M. Holt, Jaswant S. Rathore
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P-and S-wave velocity models along two perpendicular profiles on the continental shelf off Lofoten, northern Norway, have been obtained by use of three-component ocean bottom seismographs. The modelling of the data indicates significant S-wave anisotropy in the sediments and lower crust, as well as P-and S-wave anisotropy in the upper mantle. The S–wave anisotropy in the sediments is inferred to be caused by fluid-filled microcracks, aligned vertically by the present-day stress-field. The anisotropy in the lower crust and upper mantle is assumed to be related to strain-fabrics inherited from Mesozoic extensional events. The upper-mantle anisotropy is inferred to be caused by mineral alignments along steeply dipping brittle faults and fractures, whereas the lower-crustal anisotropy probably is due to steep alignment of fluid-filled pore-space related to ductile strain fabrics. The observed anisotropy thus provides valuable information about geodynamical “fingerprints” from large-scale Mesozoic deformations, as well as present-day geological processes.