Experiments on oblique rifting in brittle-ductile systems : Tectonophysics V188, N1/2, March 1991, P71–84

Abstract

Oblique rifting arises when the bulk extension direction is not perpendicular to the boundaries of a deforming zone. Several scale experiments of oblique rifting acting on a brittle-ductile system are here presented. Models are two-layer slabs of sand and silicone. Uniaxial stretching is applied oblique to the external boundaries (α = 0°, 15°, 30°, 45°, 60°, 90°). Resulting fault patterns are analysed on both the free surface and serial cross-sections. In the experiments oblique rifting is characterized by en-echelon fault patterns, mean fault trends not perpendicular to the stretching vector, and mean initial fault dips higher than for dip-slip normal faults. For low obliquity rifting (α ⩾ 45°) curved faults are frequent, displacement along them varying from dip-slip to dominantly strike-slip. For high obliquity rifting (α < 45°) motion is partitioned amongst distinct families of oblique-slip faults and strike-slip faults.