Seismic anisotropy in the eastern United States: Deep structure of a complex continental plate
International audience We have analyzed shear wave splitting recorded by portable and permanent broadband and long-period stations located in the eastern United States. Teleseismic shear waves (SKS, SKKS, and PKS) were used to retrieve the splitting parameters: the orientation of the fast wave polar...
Published in: | Journal of Geophysical Research: Solid Earth |
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ftinsu:oai:HAL:hal-01388859v1 2023-06-18T03:42:08+02:00 Seismic anisotropy in the eastern United States: Deep structure of a complex continental plate Barruol, Guilhem Silver, Paul, Vauchez, A. Laboratoire de Tectonophysique (Tectonophysique) Université Montpellier 2 - Sciences et Techniques (UM2)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS) Department of Terrestrial Magnetism Carnegie Institution Carnegie Institution for Science 1997 https://hal.univ-reunion.fr/hal-01388859 https://hal.univ-reunion.fr/hal-01388859/document https://hal.univ-reunion.fr/hal-01388859/file/Barruol_JGR_1997.pdf https://doi.org/10.1029/96JB03800 en eng HAL CCSD American Geophysical Union info:eu-repo/semantics/altIdentifier/doi/10.1029/96JB03800 hal-01388859 https://hal.univ-reunion.fr/hal-01388859 https://hal.univ-reunion.fr/hal-01388859/document https://hal.univ-reunion.fr/hal-01388859/file/Barruol_JGR_1997.pdf doi:10.1029/96JB03800 info:eu-repo/semantics/OpenAccess ISSN: 2169-9313 EISSN: 2169-9356 Journal of Geophysical Research : Solid Earth https://hal.univ-reunion.fr/hal-01388859 Journal of Geophysical Research : Solid Earth, 1997, 102 (B4), pp.8329-8348. ⟨10.1029/96JB03800⟩ [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph] info:eu-repo/semantics/article Journal articles 1997 ftinsu https://doi.org/10.1029/96JB03800 2023-06-06T00:59:08Z International audience We have analyzed shear wave splitting recorded by portable and permanent broadband and long-period stations located in the eastern United States. Teleseismic shear waves (SKS, SKKS, and PKS) were used to retrieve the splitting parameters: the orientation of the fast wave polarization plane ϕ and the delay time δt. In total, 120 seismic events were processed, allowing for more than 600 splitting measurements. Within the Appalachians, stations located in the western (external) part are characterized by δt≈1s and ϕ trending N50°– 70°E in the south and central regions and N30°–40°E in the north, closely following the trend of the orogenic belt in these areas. The transition region between north and central is characterized by δt≈1–1.3 s and by E-W trending ϕ that are at a high angle to the regional geologic trend. Measurements at two stations located in the eastern (internal) part of the belt indicate very weak anisotropy. The large-scale pattern of anisotropy is not consistent with that predicted for simple asthenospheric flow beneath the plate. Splitting along the southern and eastern margins of the continent is consistent with that expected for Grenvillian deformation, an alternative model of asthenospheric flow around the cratonic keel cannot be ruled out. Within the cratonic core, the correlation between δt and lithospheric thickness suggests a lithospheric anisotropy. Smaller-length-scale variations also argue for a significant contribution of lithospheric structures. The fabric responsible for shear wave splitting may have formed during tectonic episodes that affected the eastern United States, i.e., the Grenville and Appalachian orogenies and the subsequent rifting of the North Atlantic Ocean. Our observations in the western Appalachians suggest that the anisotropy may be preserved since the Grenvillian orogeny. The absence of detectable splitting in the two stations in the eastern Appalachians is attributed to the igneous intrusions related to the Atlantic rifting. The measurements ... Article in Journal/Newspaper North Atlantic Institut national des sciences de l'Univers: HAL-INSU Journal of Geophysical Research: Solid Earth 102 B4 8329 8348 |
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Open Polar |
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Institut national des sciences de l'Univers: HAL-INSU |
op_collection_id |
ftinsu |
language |
English |
topic |
[SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph] |
spellingShingle |
[SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph] Barruol, Guilhem Silver, Paul, Vauchez, A. Seismic anisotropy in the eastern United States: Deep structure of a complex continental plate |
topic_facet |
[SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph] |
description |
International audience We have analyzed shear wave splitting recorded by portable and permanent broadband and long-period stations located in the eastern United States. Teleseismic shear waves (SKS, SKKS, and PKS) were used to retrieve the splitting parameters: the orientation of the fast wave polarization plane ϕ and the delay time δt. In total, 120 seismic events were processed, allowing for more than 600 splitting measurements. Within the Appalachians, stations located in the western (external) part are characterized by δt≈1s and ϕ trending N50°– 70°E in the south and central regions and N30°–40°E in the north, closely following the trend of the orogenic belt in these areas. The transition region between north and central is characterized by δt≈1–1.3 s and by E-W trending ϕ that are at a high angle to the regional geologic trend. Measurements at two stations located in the eastern (internal) part of the belt indicate very weak anisotropy. The large-scale pattern of anisotropy is not consistent with that predicted for simple asthenospheric flow beneath the plate. Splitting along the southern and eastern margins of the continent is consistent with that expected for Grenvillian deformation, an alternative model of asthenospheric flow around the cratonic keel cannot be ruled out. Within the cratonic core, the correlation between δt and lithospheric thickness suggests a lithospheric anisotropy. Smaller-length-scale variations also argue for a significant contribution of lithospheric structures. The fabric responsible for shear wave splitting may have formed during tectonic episodes that affected the eastern United States, i.e., the Grenville and Appalachian orogenies and the subsequent rifting of the North Atlantic Ocean. Our observations in the western Appalachians suggest that the anisotropy may be preserved since the Grenvillian orogeny. The absence of detectable splitting in the two stations in the eastern Appalachians is attributed to the igneous intrusions related to the Atlantic rifting. The measurements ... |
author2 |
Laboratoire de Tectonophysique (Tectonophysique) Université Montpellier 2 - Sciences et Techniques (UM2)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS) Department of Terrestrial Magnetism Carnegie Institution Carnegie Institution for Science |
format |
Article in Journal/Newspaper |
author |
Barruol, Guilhem Silver, Paul, Vauchez, A. |
author_facet |
Barruol, Guilhem Silver, Paul, Vauchez, A. |
author_sort |
Barruol, Guilhem |
title |
Seismic anisotropy in the eastern United States: Deep structure of a complex continental plate |
title_short |
Seismic anisotropy in the eastern United States: Deep structure of a complex continental plate |
title_full |
Seismic anisotropy in the eastern United States: Deep structure of a complex continental plate |
title_fullStr |
Seismic anisotropy in the eastern United States: Deep structure of a complex continental plate |
title_full_unstemmed |
Seismic anisotropy in the eastern United States: Deep structure of a complex continental plate |
title_sort |
seismic anisotropy in the eastern united states: deep structure of a complex continental plate |
publisher |
HAL CCSD |
publishDate |
1997 |
url |
https://hal.univ-reunion.fr/hal-01388859 https://hal.univ-reunion.fr/hal-01388859/document https://hal.univ-reunion.fr/hal-01388859/file/Barruol_JGR_1997.pdf https://doi.org/10.1029/96JB03800 |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_source |
ISSN: 2169-9313 EISSN: 2169-9356 Journal of Geophysical Research : Solid Earth https://hal.univ-reunion.fr/hal-01388859 Journal of Geophysical Research : Solid Earth, 1997, 102 (B4), pp.8329-8348. ⟨10.1029/96JB03800⟩ |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.1029/96JB03800 hal-01388859 https://hal.univ-reunion.fr/hal-01388859 https://hal.univ-reunion.fr/hal-01388859/document https://hal.univ-reunion.fr/hal-01388859/file/Barruol_JGR_1997.pdf doi:10.1029/96JB03800 |
op_rights |
info:eu-repo/semantics/OpenAccess |
op_doi |
https://doi.org/10.1029/96JB03800 |
container_title |
Journal of Geophysical Research: Solid Earth |
container_volume |
102 |
container_issue |
B4 |
container_start_page |
8329 |
op_container_end_page |
8348 |
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