Rift inheritance controls the switch from thin- to thick-skinned thrusting and basal décollement re-localization at the subduction-to-collision transition - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Geological Society of America Bulletin Année : 2021

Rift inheritance controls the switch from thin- to thick-skinned thrusting and basal décollement re-localization at the subduction-to-collision transition

Stefano Tavani
Pablo Granado
  • Fonction : Auteur
Amerigo Corradetti
  • Fonction : Auteur
Giovanni Camanni
  • Fonction : Auteur
Gianluca Vignaroli
  • Fonction : Auteur
Stefano Mazzoli
  • Fonction : Auteur
Josep Muñoz
  • Fonction : Auteur
Mariano Parente
  • Fonction : Auteur

Résumé

Abstract In accretionary convergent margins, the subduction interface is formed by a lower plate décollement above which sediments are scraped off and incorporated into the accretionary wedge. During subduction, the basal décollement is typically located within or at the base of the sedimentary pile. However, the transition to collision implies the accretion of the lower plate continental crust and deformation of its inherited rifted margin architecture. During this stage, the basal décollement may remain confined to shallow structural levels as during subduction or re-localize into the lower plate middle-lower crust. Modes and timing of such re-localization are still poorly understood. We present cases from the Zagros, Apennines, Oman, and Taiwan belts, all of which involve a former rifted margin and point to a marked influence of inherited rift-related structures on the décollement re-localization. A deep décollement level occurs in the outer sectors of all of these belts, i.e., in the zone involving the proximal domain of pre-orogenic rift systems. Older—and shallower—décollement levels are preserved in the upper and inner zones of the tectonic pile, which include the base of the sedimentary cover of the distal portions of the former rifted margins. We propose that thinning of the ductile middle crust in the necking domains during rifting, and its complete removal in the hyperextended domains, hampered the development of deep-seated décollements during the inception of shortening. Progressive orogenic involvement of the proximal rift domains, where the ductile middle crust was preserved upon rifting, favors its reactivation as a décollement in the frontal portion of the thrust system. Such décollement eventually links to the main subduction interface, favoring underplating and the upward motion of internal metamorphic units, leading to their final emplacement onto the previously developed tectonic stack.
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Dates et versions

hal-03514460 , version 1 (06-01-2022)

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Stefano Tavani, Pablo Granado, Amerigo Corradetti, Giovanni Camanni, Gianluca Vignaroli, et al.. Rift inheritance controls the switch from thin- to thick-skinned thrusting and basal décollement re-localization at the subduction-to-collision transition. Geological Society of America Bulletin, 2021, 133 (9-10), pp.2157-2170. ⟨10.1130/B35800.1⟩. ⟨hal-03514460⟩
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