Preprints
https://doi.org/10.5194/se-2021-18
https://doi.org/10.5194/se-2021-18

  25 Feb 2021

25 Feb 2021

Review status: this preprint is currently under review for the journal SE.

Looking beyond kinematics: 3D thermo-mechanical modelling reveals the dynamic of transform margins

Anthony Jourdon1, Charlie Kergaravat1, Guillaume Duclaux2, and Caroline Huguen1 Anthony Jourdon et al.
  • 1Research & Development, Total S.A., Pau, France
  • 2Université Côte d'Azur, CNRS, Observatoire de la Côte d'Azur, IRD, Géoazur, France

Abstract. Transform margins represent ~30 % of the non-convergent margins worldwide. Their formation and evolution have long been addressed through kinematic models that do not account for the mechanical behaviour of the lithosphere. In this study, we use high resolution 3D numerical thermo-mechanical modelling to simulate and investigate the evolution of the intra-continental strain localization under oblique extension. The obliquity is set through velocity boundary conditions that range from 15° (high obliquity) to 75° (low obliquity) every 15° for strong and weak lower continental crust rheologies. Numerical models show that the formation of localized strike-slip shear zones leading to transform continental margins always follows a thinning phase during which the lithosphere is thermally and mechanically weakened. For low (75°) to intermediate (45°) obliquity cases, the strike-slip faults are not parallel to the extension direction but form an angle of 20° to 40° with the plates' motion while for higher obliquities (30° to 15°) the strike-slip faults develop parallel to the extension direction. Numerical models also show that during the thinning of the lithosphere, the stress and strain re-orient while boundary conditions are kept constant. This evolution, due to the weakening of the lithosphere, leads to a strain localization process in three major phases: (1) strain initiates in a rigid plate where structures are sub-perpendicular to the extension direction; (2) distributed deformation with local stress field variations and formation of transtensional and strike-slip structures; (3) formation of highly localized plates boundaries stopping the intra-continental deformation. Our results call for a thorough re-evaluation of the kinematic approach to studying transform margins.

Anthony Jourdon et al.

Status: open (until 17 Apr 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on se-2021-18', Sascha Brune, 25 Mar 2021 reply

Anthony Jourdon et al.

Anthony Jourdon et al.

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