GEOSCAN, résultats de la recherche


TitreNumerical mechanical modeling of thin-skinned thrust and fold belts: insights into variations in structural style
AuteurStockmal, G S; Beaumont, C; Nguyen, M; Lee, B
Source 2005, 1 pages
Séries alt.Secteur des sciences de la Terre, Contribution externe 2004180
ÉditeurAmerican Association of Petroleum Geologists |a Tulsa, OK, USA (Tulsa, OK, USA)
RéunionCanadian Society of Petroleum Geologists - American Association of Petroleum Geologists 2005 Joint Annual Convention; Calgary, Alberta; CA; juin 19-22, 2005
Documentpublication en série
Mediaen ligne; numérique
Sujetsplis; failles, chevauchement; croûte continentale; épaisseur de la croûte; evolution de la croûte; structure de la croûte; relèvement isostatique; orogénies; déformation; établissement de modèles structuraux; tectonique; géologie structurale; tectonique
ProgrammeLa mise en valeur des ressources du Nord
Résumé(disponible en anglais seulement)
The "critical wedge" existence theories of Chapple (1978), Davis et al. (1983), and Dahlen (1984) adequately describe the first-order mechanics of thin-skinned thrust-and-fold belts (TFBs). However, because they assume the wedge is everywhere on the verge of failure, these theories are inappropriate for examining the mechanics within TFBs, at scales where this assumption is invalid.
Dynamical numerical models are not similarly constrained, and allow examination of structures within the wedge, offering prospects of a deeper understanding of TFB mechanics. They provide insight into complex feedback relationships, especially those involving surface processes (erosion and sedimentation), and regional isostatic adjustment. Although the effects of erosion and sedimentation on orogenic-scale deformation are widely appreciated, a similar understanding within TFBs is lacking.
We describe numerical experiments of thin-skinned TFB deformation using a 2-D finite-element continuum mechanics code capable of accommodating very large strain. In the undeformed state, each model is generally composed of layered materials of specified thickness, extent, rheology (e.g., Coulomb plastic), and mechanical properties. During deformation, the upper surface of the thickening wedge is exposed to surface processes, allowing erosional removal and redistribution of material to sedimentary basins, and regional isostatic adjustment to thickening is accommodated. Although faults are not modeled explicitly, narrow high-strain zones develop, forming structures very similar in style to those in TFBs. Model structures include far-traveled thrust sheets, irregular-roof and smooth-roof duplexes, antiformal stacks, backthrusts, pop-ups, nascent triangle zones, detachment folds, break-thrusts, and piggy-back basins. Variations in fundamental structural style can result from subtle variations in input parameters.