uu.seUppsala University Publications
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Seismic anisotropy from compositional banding in granulites from the deep magmatic arc of Fiordland, New Zealand
Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.ORCID iD: 0000-0002-9385-7614
2017 (English)In: Earth and Planetary Science Letters, ISSN 0012-821X, E-ISSN 1385-013X, Vol. 477, p. 156-167Article in journal (Refereed) Published
Abstract [en]

We present calculated seismic velocities and anisotropies of mafic granulites and eclogites from the Cretaceous deep lower crust (similar to 40-65 km) of Fiordland, New Zealand. Both rock types show a distinct foliation defined by cm-scale compositional banding. Seismic properties are estimated using the Asymptotic Expansion Homogenisation - Finite Element (AEH-FE) method that, unlike the commonly used Voigt-Reuss-Hill homogenisation, incorporates the phase boundary network into calculations. The predicted mean P- and S-wave velocities are consistent with previously published data for similar lithologies from other locations (e.g., Kohistan Arc), although we find higher than expected anisotropies (AV(P) similar to 5.0-8.0%, AV(S) similar to 3.0-6.5%) and substantial S-wave splitting along foliation planes in granulites. This seismic signature of granulites results from a density and elasticity contrast between cm-scale pyroxene +/- garnet stringers and, plagioclase matrix rather than from crystallographic orientations alone. Banded eclogites do not show elevated anisotropies as the contrast in density and elastic constants of garnet and pyroxene is too small. The origin of compositional banding in Fiordland granulites is primarily magmatic and structures described here are expected to be typical for the base of present day magmatic arcs. Hence, we identify a new potential source of anisotropy within this geotectonic setting.

Place, publisher, year, edition, pages
2017. Vol. 477, p. 156-167
Keywords [en]
seismic anisotropy; lower crust; compositional banding; EBSD; granulite; Fiordland
National Category
Geophysics
Identifiers
URN: urn:nbn:se:uu:diva-329200DOI: 10.1016/j.epsl.2017.08.017ISI: 000413132000015OAI: oai:DiVA.org:uu-329200DiVA, id: diva2:1139900
Available from: 2017-09-10 Created: 2017-09-10 Last updated: 2018-01-25Bibliographically approved

Open Access in DiVA

No full text in DiVA

Other links

Publisher's full texthttp://www.sciencedirect.com/science/article/pii/S0012821X17304648

Authority records BETA

Almqvist, Bjarne

Search in DiVA

By author/editor
Almqvist, Bjarne
By organisation
Geophysics
In the same journal
Earth and Planetary Science Letters
Geophysics

Search outside of DiVA

GoogleGoogle Scholar

doi
urn-nbn

Altmetric score

doi
urn-nbn
Total: 128 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf