| Titre | Coupled evolution of deformation, pore fluid pressure, and fluid flow in shallow subduction forearcs |
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| Auteur | Sun, T ; Ellis, S;
Saffer, D |
| Source | Journal of Geophysical Research, Solid Earth vol. 125, issue 3, e2019JB019101, 2020 p. 1-25, https://doi.org/10.1029/2019JB019101 |
| Année | 2020 |
| Séries alt. | Ressources naturelles Canada, Contribution externe 20200007 |
| Éditeur | American Geophysical Union |
| Document | publication en série |
| Lang. | anglais |
| DOI | https://doi.org/10.1029/2019JB019101 |
| Media | papier; en ligne; numérique |
| Formats | pdf; html |
| Sujets | tectonique de plaques; milieux tectoniques; modèles; zones de subduction; déformation; fluage; pressions interstitielles; milieu hydrologique; transport des sediments; assèchement; géologie du substratum
rocheux; caractéristiques structurales; failles; horsts; fosses d'effondrement; détermination des contraintes; géologie du socle; perméabilité; porosité; biseaux sédimentaires; épaisseur de la couverture meuble; tectonique; hydrogéologie; géologie
structurale; sédimentologie; Sciences et technologie; Nature et environnement |
| Illustrations | coupes schématiques transversales; représentations schématiques; tableaux; modèles; organigrammes; graphiques; profils |
| Diffusé | 2020 03 09 |
| Résumé | (disponible en anglais seulement)
Deformation and fluid flow in subduction zone forearcs are dynamically coupled, but our quantitative understanding of their coupling is incomplete. In this
work, we investigate the hydrological and mechanical coupling in shallow forearcs, using a Lagrangian-Eulerian finite element model that incorporates constitutive and transport properties of sediments and faults constrained by laboratory and field
measurements. Wide-ranging observations show that sediment thickness and composition, plate convergence rate, basement strength and roughness, and subducting slab dip angle vary between subduction zones. We therefore systematically study their
effects on forearc stress and pore fluid pressure states, consolidation and dewatering patterns, and margin morphology. Our models, with the incorporation of a simple description of permeability enhancement along fault damage zones, yield a range of
fault permeability (10 to the -13th power - 10 to the -17th power m2) consistent with previous estimates and describe the important role of upper plate splay faults in causing heterogeneous dewatering and consolidation patterns and in modulating
effective normal stress on the plate interface. Spatial variations in tectonic loading and sediment consolidation can also be caused by subducting basement roughness such as a horst-and-graben structure. For typically observed relief and spacing, our
models predict locally enhanced porosity reduction by up to 50% at the downdip edge of the horsts and anomalously high sediment porosity above the geometrical highs. At the margin scale, our results demonstrate that sediment permeability and
thickness are dominant controls on fluid overpressure, sediment compaction, and megathrust strength. Rough and frictionally strong megathrusts produce similar effects in driving high wedge tapers. |
| GEOSCAN ID | 323647 |
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