Evidence for deep crustal seismic rupture in a granulite-facies, intraplate, strike-slip shear zone, northern Saskatchewan, Canada
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Résumé
Research Article| September 24, 2018 Evidence for deep crustal seismic rupture in a granulite-facies, intraplate, strike-slip shear zone, northern Saskatchewan, Canada Omero F. Orlandini; Omero F. Orlandini † 1Department of Geological Sciences, University of Colorado, UCB 399, Boulder, Colorado 80309-0399, USA †orlandin@colorado.edu Search for other works by this author on: GSW Google Scholar Kevin H. Mahan; Kevin H. Mahan 1Department of Geological Sciences, University of Colorado, UCB 399, Boulder, Colorado 80309-0399, USA Search for other works by this author on: GSW Google Scholar Michael J. Williams; Michael J. Williams 2Department of Geosciences, University of Massachusetts, 627 North Pleasant Street, 233 Morrill Science Center, Amherst, Massachusetts 01003-9297, USA Search for other works by this author on: GSW Google Scholar Sean P. Regan; Sean P. Regan 2Department of Geosciences, University of Massachusetts, 627 North Pleasant Street, 233 Morrill Science Center, Amherst, Massachusetts 01003-9297, USA Search for other works by this author on: GSW Google Scholar Karl J. Mueller Karl J. Mueller 1Department of Geological Sciences, University of Colorado, UCB 399, Boulder, Colorado 80309-0399, USA Search for other works by this author on: GSW Google Scholar Author and Article Information Omero F. Orlandini † 1Department of Geological Sciences, University of Colorado, UCB 399, Boulder, Colorado 80309-0399, USA Kevin H. Mahan 1Department of Geological Sciences, University of Colorado, UCB 399, Boulder, Colorado 80309-0399, USA Michael J. Williams 2Department of Geosciences, University of Massachusetts, 627 North Pleasant Street, 233 Morrill Science Center, Amherst, Massachusetts 01003-9297, USA Sean P. Regan 2Department of Geosciences, University of Massachusetts, 627 North Pleasant Street, 233 Morrill Science Center, Amherst, Massachusetts 01003-9297, USA Karl J. Mueller 1Department of Geological Sciences, University of Colorado, UCB 399, Boulder, Colorado 80309-0399, USA †orlandin@colorado.edu Publisher: Geological Society of America Received: 05 Sep 2017 Revision Received: 11 May 2018 Accepted: 27 Jun 2018 First Online: 24 Sep 2018 Online Issn: 1943-2674 Print Issn: 0016-7606 © 2018 Geological Society of America GSA Bulletin (2019) 131 (3-4): 403–425. https://doi.org/10.1130/B31922.1 Article history Received: 05 Sep 2017 Revision Received: 11 May 2018 Accepted: 27 Jun 2018 First Online: 24 Sep 2018 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Omero F. Orlandini, Kevin H. Mahan, Michael J. Williams, Sean P. Regan, Karl J. Mueller; Evidence for deep crustal seismic rupture in a granulite-facies, intraplate, strike-slip shear zone, northern Saskatchewan, Canada. GSA Bulletin 2018;; 131 (3-4): 403–425. doi: https://doi.org/10.1130/B31922.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract Pseudotachylyte veins are solidified frictional melt generated by localized high-strain-rate deformation, and they are commonly considered to be reliable geological indicators of seismic slip. While originally thought to occur primarily in the upper crust, field studies suggest pseudotachylyte can also form far below the frictional-viscous transition. This implies a more complex interplay between brittle and crystal-plastic deformation in crustal-scale fault systems. We report a new example of deep pseudotachylyte from the Paleoproterozoic granulite-facies strike-slip Cora Lake shear zone in northern Saskatchewan, Canada. Multiple generations of pseudotachylyte have been variably overprinted by plastic deformation and growth of high-grade metamorphic mineral assemblages (including garnet, orthopyroxene, and/or clinopyroxene). Undeformed pseudotachylyte generation surfaces locally display sinistral offsets, and deformed pseudotachylyte shows unambiguous shear sense indicators compatible with left-lateral Cora Lake shear zone kinematics. The vein networks are commonly proximal to and inherit kinematically compatible semibrittle shear fractures. Thermobarometry and modeling of mineral stability fields for the overprinted pseudotachylyte suggest vein generation between 0.7 and 0.8 GPa and 700 °C and 800 °C (corresponding to depths from 24 to 28 km). Combined with the kinematic compatibility and the well-constrained regional exhumation history, this suggests that the Cora Lake pseudotachylyte formed contemporaneously with the waning stages of deformation in the shear zone and constitutes one of the deepest examples of fault-related pseudotachylyte yet reported in North America. Evidence exists for several possible formation mechanisms, including in situ generation via ductile shear heating–induced plastic instabilities, as well as from interaction with earthquakes nucleating in the overlying brittle fault system. All of these possible mechanisms ultimately suggest a more rheologically complex environment than might typically be expected for these lower-crustal pressure and temperature conditions. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.
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Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,001 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,003 | 0,010 |
| Études des sciences et des technologies | 0,002 | 0,001 |
| Communication savante | 0,001 | 0,000 |
| Science ouverte | 0,001 | 0,001 |
| Intégrité de la recherche | 0,001 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,005 | 0,001 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».