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.
Toward a better understanding of the Late Neogene strike-slip restraining bend in Jamaica: geodetic, geological, and seismic constraints
Published:January 01, 2007
P. Mann, C. Demets, M. Wiggins-Grandison, 2007. "Toward a better understanding of the Late Neogene strike-slip restraining bend in Jamaica: geodetic, geological, and seismic constraints", Tectonics of Strike-Slip Restraining and Releasing Bends, W. D. Cunningham, P. Mann
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We describe the regional fault pattern, geological setting and active fault kinematics of Jamaica, from published geological maps, earthquakes and GPS-based geodesy, to support a simple tectonic model for both the initial stage of restraining-bend formation and the subsequent stage of bend bypassing. Restraining-bend formation and widespread uplift in Jamaica began in the Late Miocene, and were probably controlled by the interaction of roughly east–west-trending strike-slip faults with two NNW-trending rifts oriented obliquely to the direction of ENE-trending, Late Neogene interplate shear. The interaction of the interplate strike-slip fault system (Enriquillo- Plantain Garden fault zone) and the oblique rifts has shifted the strike-slip fault trace c. 50 km to the north and created the 150-km-long by 80-km-wide restraining bend that is now morphologically expressed as the island of Jamaica. Recorded earthquakes and recent GPS results from Jamaica illustrate continued bend evolution during the most recent phase of strike-slip displacement, at a minimum GPS-measured rate of 8±1 mm/a. GPS results show a gradient in left-lateral interplate strain from north to south, probably extending south of the island, and a likely gradient along a ENE–WSW cross-island profile. The observed GPS velocity field suggests that left-lateral shear continues to be transmitted across the Jamaican restraining bend by a series of intervening bend structures, including the Blue Mountain uplift of eastern Jamaica.