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Seismic anisotropy and its geological implications on the Lofoten (Norway) continental shelf: Seismic anisotropy off Lofoten

By
Rolf Mjelde
Rolf Mjelde
Institute of Solid Earth Physics, Allégt. 41, University of Bergen, 5007 Bergen. Norway
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Published:
January 01, 1996

Abstract

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.

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Contents

Seismic Anisotropy

Erling Fjær
Erling Fjær
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Rune M. Holt
Rune M. Holt
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Jaswant S. Rathore
Jaswant S. Rathore
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Society of Exploration Geophysicists
ISBN electronic:
9781560802693
Publication date:
January 01, 1996

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