Horses and duplexes in extensional regimes: A scale-modeling contribution

Gabrielsen, Roy H.; Clausen, Jill A.

doi:10.1130/0-8137-1193-2.207

Cited by 12 publications

(8 citation statements)

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“…The fault zones studied here show a similar damaged structure characterized by a network of more or less developed anastomosing sliding surfaces that individualize lenses of damaged material (Figure 2). Such lenses have been described in various tectonic regimes from the seismic scale [ Gibbs , 1983, 1984] down to the millimeter scale [ Gabrielsen and Clausen , 2001; Clausen et al , 2003; Berg , 2004; Christensen , 2004]. We propose here that elastic interactions related to linkage of many discrete slip surfaces, controlling the generation of the multiscale bumpy lenses observed on the scanned fault outcrops (Figure 2), could be the scale‐free process at the origin of fault roughness.…”

Section: Discussionmentioning

confidence: 57%

Roughness of fault surfaces over nine decades of length scales

Candela¹,

Renard²,

Klinger³

et al. 2012

J. Geophys. Res.

296

338

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[1] We report on the topographic roughness measurements of five exhumed faults and thirteen surface earthquake ruptures over a large range of scales: from 50 mm to 50 km. We used three scanner devices (LiDAR, laser profilometer, white light interferometer), spanning complementary scale ranges from 50 mm to 10 m, to measure the 3-D topography of the same objects, i.e., five exhumed slip surfaces (Vuache-Sillingy, Bolu, Corona Heights, Dixie Valley, Magnola). A consistent geometrical property, i.e., self-affinity, emerges as the morphology of the slip surfaces shows at first order, a linear behavior on a log-log plot where axes are fault roughness and spatial length scale, covering five decades of length-scales. The observed fault roughness is scale dependent, with an anisotropic self-affine behavior described by four parameters: two power law exponents H, constant among all the faults studied but slightly anisotropic (H k = 0.58 AE 0.07 in the slip direction and H ? = 0.81 AE 0.04 perpendicular to it), and two pre-factors showing variability over the faults studied. For larger scales between 200 m and 50 km, we have analyzed the 2-D roughness of the surface rupture of thirteen major continental earthquakes. These ruptures show geometrical properties consistent with the slip-perpendicular behavior of the smaller-scale measurements. Our analysis suggests that the inherent non-alignment between the exposed traces and the along or normal slip direction results in sampling the slip-perpendicular geometry. Although a data gap exists between the scanned fault scarps and rupture traces, the measurements are consistent within the error bars with a single geometrical description, i.e., consistent dimensionality, over nine decades of length scales.

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Section: Discussionmentioning

confidence: 57%

Roughness of fault surfaces over nine decades of length scales

Candela¹,

Renard²,

Klinger³

et al. 2012

J. Geophys. Res.

296

338

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“…Faults grow by linking of individual fault segments developing a complex and often irregular fault trace of soft linked and hard linked faults and fault lenses (e.g., Childs et al 1997). Further movement shears of asperities and break down lenses to develop a smoother fault core geometry often outlined by a through going slip surface(s) (Gabrielsen & Clausen 2001;. Further, the irregularity and the geometry of fault segments can be controlled by the host rock mechanical strength, i.e.…”

Section: Fault Architecturementioning

confidence: 99%

Extensional fault cores in micritic carbonate – Case studies from the Gulf of Corinth, Greece

Bastesen

Braathen

Nøttveit

et al. 2009

Journal of Structural Geology

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“…The term “extensional duplex” was established by Gibbs [1984]to describe the structural style characterized by connected extensional fault segments limiting rock lenses (horses) commonly associated with ramp‐flat‐ramp normal faults, equivalent to the duplexes defined in contractional and strike‐slip faults [ Boyer and Elliott , 1982; Woodcock and Fischer , 1986]. Despite the vast literature describing the styles of extensional faulting, natural examples of ramp‐flat‐ramp normal faults and extensional duplexes are very scarce [ Root , 1990; Benedicto et al , 1999; Gabrielsen and Clausen , 2001; Vetti and Fossen , 2012]. In the Betic Cordillera, several examples have been described in basement metamorphic rocks developed in deeper parts of the crust and latterly exhumed [e.g., Martínez ‐ Martínez et al , 2002].…”

Section: Discussionmentioning

confidence: 99%

Evolution of near‐surface ramp‐flat‐ramp normal faults and implication during intramontane basin formation in the eastern Betic Cordillera (the Huércal‐Overa Basin, SE Spain)

Pedrera¹,

Galindo-Zaldı́var²,

Lamas‐Fernández³

et al. 2012

Tectonics

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[1] The nucleation, propagation, and associated folding of ramp-flat-ramp normal faults were analyzed from field examples developed in a brittle/ductile multilayer sequence of the Huércal-Overa Basin (SE Spain). Gently dipping sandy silt layers, which display a low cohesive strength (C 0 = 7 kPa, m = 34 ), favor the development of extensional detachments. A tectonic origin instead of a possible gravitational origin is supported by the perpendicularity between the paleoslope direction of the fluvial-deltaic environment inferred from imbricated pebbles, and the senses of movement deduced from fault slickenlines. The link between high-angle normal faults (HANFs) -formed at different levels in the layered sequence-with horizontal fault segments comes to develop ramp-flat-ramp normal faults with associated roll-over in the hanging wall. Observed extensional duplexes are formed by parallel detachments connected through synthetic Riedel faults. These Riedel faults would produce the back-rotation of the individual blocks (horses), i.e., extensional folding of the originally subhorizontal layers. There is no correlation between the analyzed ramp-flat-ramp normal faults, accommodating south-southeastward extension during Serravallian-lower Tortonian, and either the regional Alpujarride/ Nevado-Filabride west-directed extensional shear zone or the top-to-the-north detachments within Alpujarride units, which are clearly sealed by Serravallian-lower Tortonian sediments. Therefore, the studied normal faults are restricted to the brittle/ductile multilayer fluvio/deltaic sequence and accommodate moderate late extension instead of belonging to a large crustal extensional system connected with a regional detachment at depth. Therefore, the basin formed in a moderate crustal thickness context where small and medium-scale extensional systems were subordinate structures. These natural examples support the development of low-angle normal faults at very shallow crustal levels in multilayer sequences with suitable rheological conditions. Citation: Pedrera, A., J. Galindo-Zaldívar, F. Lamas, and A. Ruiz-Constán (2012), Evolution of near-surface ramp-flat-ramp normal faults and implication during intramontane basin formation in the eastern

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Horses and duplexes in extensional regimes: A scale-modeling contribution

Cited by 12 publications

References 0 publications

Roughness of fault surfaces over nine decades of length scales

Roughness of fault surfaces over nine decades of length scales

Extensional fault cores in micritic carbonate – Case studies from the Gulf of Corinth, Greece

Evolution of near‐surface ramp‐flat‐ramp normal faults and implication during intramontane basin formation in the eastern Betic Cordillera (the Huércal‐Overa Basin, SE Spain)

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