Fault development and interaction in distributed strike-slip shear zones: an experimental approach
G. Schreurs, 2003. "Fault development and interaction in distributed strike-slip shear zones: an experimental approach", Intraplate Strike-Slip Deformation Belts, F. Storti, R. E. Holdsworth, F. Salvini
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Analogue model experiments using both brittle and viscous materials were performed to investigate the development and interaction of strike-slip faults in zones of distributed shear deformation. At low strain, bulk dextral shear deformation of an initial rectangular model is dominantly accommodated by left-stepping, en echelon strike-slip faults (Riedel shears, R) that form in response to the regional (bulk) stress field. Push-up zones form in the area of interaction between adjacent left-stepping Riedel shears. In cross sections, faults bounding push-up zones have an arcuate shape or merge at depth. Adjacent left-stepping R shears merge by sideways propagation or link by short synthetic shears that strike subparallel to the bulk shear direction. Coalescence of en echelon R shears results in major, through-going faults zones (master faults). Several parallel master faults develop due to the distributed nature of deformation. Spacing between master faults is related to the thickness of the brittle layers overlying the basal viscous layer. Master faults control to a large extent the subsequent fault pattern. With increasing strain, relatively short antithetic and synthetic faults develop mostly between old, but still active master faults. The orientation and evolution of the new faults indicate local modifications of the stress field. In experiments lacking lateral borders, closely spaced parallel antithetic faults (cross faults) define blocks that undergo clockwise rotation about a vertical axis with continuing deformation. Fault development and fault interaction at different stages of shear strain in our models show similarities with natural examples that have undergone distributed shear.
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Intraplate Strike-Slip Deformation Belts
Intraplate strike-slip deformation belts are common tectonic features, particularly at convergent plate boundaries, where they are produced by both oblique convergence and continental indentation. These lithosphere-scale structures, which also occur in other geodynamic environments such as passive margins, are characterized by complex structural architectures, by the occurrence of large earthquakes, and by the fast uplift and/or subsidence of localized crustal sectors.
Intraplate strike-slip belts can also control the ascent and emplacement of deeply sourced magmas. In some cases, intraplate strike-slip belts link with oceanic fracture zones and transform faults, transferring transform shear from the ridges to the interior of the plates. This evidence has an important impact of the classical concept of transform faulting.
This volume contains 13 papers from an international field of contributors. Studies of intraplate strike-slip deformation belts from Africa, Antarctica, Eurasia, North America and South America are included.