Lithospheric anisotropy structure inferred from collocated teleseismic and magnetotelluric observations

Great Slave Lake shear zone, northern Canada

David W. Eaton*, Alan G. Jones, Ian J. Ferguson

*Corresponding author for this work

Research output: Contribution to journalArticle

50 Citations (Scopus)

Abstract

Accurate interpretation of SKS shear-wave splitting observations requires inherently indeterminate depth information. Magnetotelluric electrical anisotropies are depth-constrained, and thereby offer possible resolution of the SKS conundrum. MT and teleseismic instruments, deployed across the Great Slave Lake shear zone, northern Canada, investigated lithospheric anisotropy and tested a hypothesis that seismic and electrical anisotropy obliquity can infer mantle strain shear-sense. Lithospheric mantle MT strike (N60°E) differs significantly from crustal MT strike (N30°E). SKS splitting vectors outside the shear zone exhibit single-layer anisotropy with fast axis parallel to upper-mantle MT strike and oblique to present-day plate motion (N135°W). Back-azimuth sensitivity at sites within the ∼ 30 km wide shear-zone imply more complex layering, with two-layer inversion yielding an upper layer of ∼N20°E and a lower layer of ∼N66°E. The MT data help to constrain the depth location of SKS anisotropy and, taken together, support a model of fossil lithospheric anisotropy.

Original languageEnglish
Article numberL19614
Pages (from-to)1-4
Number of pages4
JournalGeophysical Research Letters
Volume31
Issue number19
DOIs
Publication statusPublished - 16 Oct 2004
Externally publishedYes

Keywords

  • 7205 Seismology: Continental crust (1242)
  • 7218 Seismology: Lithosphere and upper mantle
  • 8110 Tectonophysics: Continental tectonics - general (0905)

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