Tectonics of strike-slip restraining and releasing bends
Published:January 01, 2007
One of the remarkable tectonic features of the Earths crust is the widespread presence of long, approximately straight and geomorphically prominent strike-slip faults which are a kinematic consequence of large-scale motion of plates on a sphere(Wilson 1965). Strike-slip faults form in continental and oceanic transform plate boundaries; in intraplate settings as a continental interior response to a plate collision; and can occur as transfer zones connecting normal faults in rift systems and thrust faults in fold thrust belts (Woodcock 1986; Sylvester 1988;Yeats et al. 1997; Marshak et al. 2003). Strike-slip faults also are common in obliquely convergent subduction settings where interplate strain is partitioned into arc-parallel strike-slip zones within the fore-arc, arc or back-arc region (Beck 1983; Jarrard 1986;Sieh & Natawidjaja 2000).
When strike-slip faults initiate in natural and experimental settings, they commonly consist of en échelon fault and fold segments (Cloos 1928;Riedel 1929; Tchalenko 1970; Wilcox et al.1973). With increased strike-slip displacement,and independent of fault scale (Tchalenko 1970),fault segments link, and the linked areas along the principal displacement zone may define alternating areas of localized convergence and divergence along the length of the strike-slip fault system(Fig. 1; Crowell 1974; Christie-Blick & Biddle1985; Gamond 1987). Typically, divergent and convergentbends are defined as offset areas where bounding strike-slip faults are continuously linked and continuously curved across the offset, whereas more rhomboidally shaped stepovers are defined as zones of slip transfer between overstepping, but distinctly separate and subparallel strike slip faults (Wilcox et al. 1973; Crowell 1974;Aydin & Nur 1982, 1985). However, fault stopovers may evolve into continuous fault bends as the bounding faults and connected splays propagate and link across the stepover (e.g. Zhang et al.1989; McClay & Bonora 2001). Thus, the two terms and fault bend are often used interchangeably.
Figures & Tables
Tectonics of Strike-Slip Restraining and Releasing Bends
Restraining and releasing bends are common, but enigmatic features of strike-slip fault systems occurring in all crustal environments and at regional to microscopic scales of observation. Regional-scale restraining bends are sites of mountain building, transpressional deformation and basement exhumation, whereas releasing bends are sites of topographic subsidence, transtensional deformation, basin sedimentation and possible volcanism and economic mineralization. Because restraining and releasing bends often occur as singular self-contained domains of complex deformation, they are appealing natural laboratories for Earth scientists to study fault processes, earthquake seismology, active faulting and sedimentation, fault and fluid-flow relationships, links between tectonics and topography, tectonic and erosional controls on exhumation, and tectonic geomorphology.
This volume addresses the tectonic complexity and diversity of strike-slip restraining and releasing bends with 18 contributions divided into four thematic sections: (1) a topical review of fault bends and their global distribution; (2) bends, sedimentary basins and earthquake hazards; (3) restraining bends, transpressional deformation and basement controls on development; (4) releasing bends, transtensional deformation and fluid flow.