Seismic velocities, anisotropy and deformation in Siberian cratonic mantle: EBSD data on xenoliths from the Udachnaya kimberlite
The study presents microstructures and crystallographic preferred orientations (CPO) of minerals obtained by electron back-scattered diffraction (EBSD) in a suite of 23 fresh mantle xenoliths (20 peridotites, 2 eclogites and 1 pyroxenite) from the Udachnaya kimberlite in central Siberian craton. The...
| Main Authors: | , , , , , |
|---|---|
| Format: | Journal Article |
| Published: |
Elsevier BV
2011
|
| Online Access: | http://hdl.handle.net/20.500.11937/67762 |
| _version_ | 1848761651244826624 |
|---|---|
| author | Bascou, J. Doucet, Luc-Serge Saumet, S. Ionov, D. Ashchepkov, I. Golovin, A. |
| author_facet | Bascou, J. Doucet, Luc-Serge Saumet, S. Ionov, D. Ashchepkov, I. Golovin, A. |
| author_sort | Bascou, J. |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | The study presents microstructures and crystallographic preferred orientations (CPO) of minerals obtained by electron back-scattered diffraction (EBSD) in a suite of 23 fresh mantle xenoliths (20 peridotites, 2 eclogites and 1 pyroxenite) from the Udachnaya kimberlite in central Siberian craton. The suite includes coarse spinel- and garnet-facies peridotites equilibrated at 760-1000°C from the upper part of the mantle lithosphere (45-160km) and porphyroclastic garnet peridotites from the base of the lithosphere (160-210km; 1200-1320°C). The data indicate that dislocation creep is the main deformation mechanism in the peridotites and eclogites. The CPO patterns of olivine suggest a dominant activation of the (010) [100] slip system. Within this general pattern, coarse peridotites show a better alignment of [100] -olivine while porphyroclastic rocks have a better alignment of [010]-olivine. Recrystallization in the porphyroclastic peridotites reduces olivine grain size and facilitates the development of a mosaic matrix that leads to a decrease in the CPO strength. Orthopyroxene in peridotites slips parallel to (100) [001] ; clinopyroxene shows a clear slip direction on [001] in both peridotites and eclogites. Seismic properties estimated from the CPO data and modal abundances of major minerals show significant differences between peridotites, eclogites and pyroxenites; some differences also exist between peridotite types. Importantly, coarse peridotites have much higher anisotropy than eclogites and may yield higher P-wave velocities in the fast direction (V p =8.8km/s). Thus, the extremely high sub-Moho velocities (V p > 8.7km/s) reported from some seismic profiles in the Siberian craton can be better explained by strong anisotropy of coarse peridotites in a horizontally foliated mantle rather than by the presence of abundant eclogites. © 2010 Elsevier B.V. |
| first_indexed | 2025-11-14T10:35:03Z |
| format | Journal Article |
| id | curtin-20.500.11937-67762 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-14T10:35:03Z |
| publishDate | 2011 |
| publisher | Elsevier BV |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-677622018-05-18T08:05:33Z Seismic velocities, anisotropy and deformation in Siberian cratonic mantle: EBSD data on xenoliths from the Udachnaya kimberlite Bascou, J. Doucet, Luc-Serge Saumet, S. Ionov, D. Ashchepkov, I. Golovin, A. The study presents microstructures and crystallographic preferred orientations (CPO) of minerals obtained by electron back-scattered diffraction (EBSD) in a suite of 23 fresh mantle xenoliths (20 peridotites, 2 eclogites and 1 pyroxenite) from the Udachnaya kimberlite in central Siberian craton. The suite includes coarse spinel- and garnet-facies peridotites equilibrated at 760-1000°C from the upper part of the mantle lithosphere (45-160km) and porphyroclastic garnet peridotites from the base of the lithosphere (160-210km; 1200-1320°C). The data indicate that dislocation creep is the main deformation mechanism in the peridotites and eclogites. The CPO patterns of olivine suggest a dominant activation of the (010) [100] slip system. Within this general pattern, coarse peridotites show a better alignment of [100] -olivine while porphyroclastic rocks have a better alignment of [010]-olivine. Recrystallization in the porphyroclastic peridotites reduces olivine grain size and facilitates the development of a mosaic matrix that leads to a decrease in the CPO strength. Orthopyroxene in peridotites slips parallel to (100) [001] ; clinopyroxene shows a clear slip direction on [001] in both peridotites and eclogites. Seismic properties estimated from the CPO data and modal abundances of major minerals show significant differences between peridotites, eclogites and pyroxenites; some differences also exist between peridotite types. Importantly, coarse peridotites have much higher anisotropy than eclogites and may yield higher P-wave velocities in the fast direction (V p =8.8km/s). Thus, the extremely high sub-Moho velocities (V p > 8.7km/s) reported from some seismic profiles in the Siberian craton can be better explained by strong anisotropy of coarse peridotites in a horizontally foliated mantle rather than by the presence of abundant eclogites. © 2010 Elsevier B.V. 2011 Journal Article http://hdl.handle.net/20.500.11937/67762 10.1016/j.epsl.2011.01.016 Elsevier BV restricted |
| spellingShingle | Bascou, J. Doucet, Luc-Serge Saumet, S. Ionov, D. Ashchepkov, I. Golovin, A. Seismic velocities, anisotropy and deformation in Siberian cratonic mantle: EBSD data on xenoliths from the Udachnaya kimberlite |
| title | Seismic velocities, anisotropy and deformation in Siberian cratonic mantle: EBSD data on xenoliths from the Udachnaya kimberlite |
| title_full | Seismic velocities, anisotropy and deformation in Siberian cratonic mantle: EBSD data on xenoliths from the Udachnaya kimberlite |
| title_fullStr | Seismic velocities, anisotropy and deformation in Siberian cratonic mantle: EBSD data on xenoliths from the Udachnaya kimberlite |
| title_full_unstemmed | Seismic velocities, anisotropy and deformation in Siberian cratonic mantle: EBSD data on xenoliths from the Udachnaya kimberlite |
| title_short | Seismic velocities, anisotropy and deformation in Siberian cratonic mantle: EBSD data on xenoliths from the Udachnaya kimberlite |
| title_sort | seismic velocities, anisotropy and deformation in siberian cratonic mantle: ebsd data on xenoliths from the udachnaya kimberlite |
| url | http://hdl.handle.net/20.500.11937/67762 |