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- Title
Initiation and growth of salt-based thrust belts on passive margins: results from physical models.
- Authors
Dooley, Tim P.; Jackson, Martin P. A.; Hudec, Michael R.
- Abstract
Scaled sandbox models simulated primary controls on the kinematics of the early structural evolution of salt-detached, gravity-driven thrust belts on passive margins. Models had a neutral-density, brittle overburden overlying a viscous décollement layer. Deformation created linked extension–translation–shortening systems. The location of initial brittle failure of the overburden was sensitive to perturbations at the base of the salt. Salt pinch-out determined the seaward limit of the thrust belt. The thrust belts were dominated by pop-up structures or detachment folds cut by break thrusts. Pop-ups were separated by flat-bottomed synclines that were partially overthrust. Above a uniformly dipping basement, thrusts initiated at the salt pinch-out then consistently broke landward. In contrast, thrust belts above a seaward-flattening hinged basement nucleated above the hinge and then spread both seaward and landward. The seaward-dipping taper of these thrust belts was much lower than typical, frictional, Coulomb-wedge models. Towards the salt pinch-out, frictional resistance increased, thrusts verged strongly seawards and the dip of the taper reversed as the leading thrust overrode this pinch-out. We attribute the geometry of these thrust belts to several causes. (1) Low friction of the basal décollement favours near-symmetric pop-ups. (2) Mobile salt migrates away from local loads created by overthrusting, which reduces the seaward taper of the thrust belt. (3) In this gravity-driven system, shortening quickly spreads to form wide thrust belts, in which most of the strain overlapped in time.
- Subjects
SALT pans (Geology); SALT deposits; KINEMATICS; FRICTIONAL resistance (Hydrodynamics); IGNEOUS rocks; METAMORPHIC rocks
- Publication
Basin Research, 2007, Vol 19, Issue 1, p165
- ISSN
0950-091X
- Publication type
Article
- DOI
10.1111/j.1365-2117.2007.00317.x