Kinematic models of plane-roofed duplex styles

Groshong, Richard H.; Usdansky, Steven I.

doi:10.1130/spe222-p197

Cited by 26 publications

(2 citation statements)

References 10 publications

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“…It is possible with our algorithm to simulate duplexes [Boyer and Elliott, 1982] with a perfectly planar horizontal roof thrust ( Figure 6), whereas the simulation of duplexes with the Suppean faultbend fold model, which keeps the layer thickness constant, leads to roof thrusts with a rugose geometry [Groshong and Usdansky, 1988;Cruikshank et al, 1989]. Natural examples of roof duplexes are often planar [Groshong and Usdansky, 1988], especially if there is a strong contrast in mechanical competence across the roof thrust (R. Groshong, verbal communication, 1990). Furthermore, it seems to us intuitively that transport along a flat roof thrust should consume less energy than transport along a fault with an irregular surface, which suggests that our model is more realistic.…”

Section: Ferences: (1) Suppe's Model Is Not Based On Kinematic Transfmentioning

confidence: 99%

Kinematic modeling of cross‐sectional deformation sequences by computer simulation

Contreras¹,

Suter²

1990

J. Geophys. Res.

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We derive a kinematic algorithm which permits simulation of postulated cross‐sectional deformation sequences in sedimentary rocks affected by faulting, fault‐related folding, and simple shear. The transformations are to a more deformed state and are formulated analytically in terms of the less deformed configuration (forward modeling, Lagrangian description). The medium is subdivided into domains of constant dip and homogeneous displacement vector fields which are delimited by the axial planes of the fault inflections. The displacement trajectory is of constant length for all the displaced particles throughout the medium and parallel to the underlying active fault segment. As a consequence, the deformation path is continuous but not smooth and causes an angular style of parallel folding, except at the deformation front where the layer thickness is not conserved. The inhomogeneity of the displacement vector field across axial planes introduces longitudinal and angular shear strains, whereas the area of the medium remains constant. These strains, which are superposed on the externally applied simple shear, make the mapping transformation unconformal. We define the stratigraphic layering of the undeformed medium by an approximating body of finite quadrilateral elements, evaluate the defined displacement functions for the grid nodes, and graph the deformed mesh. Eventually, we create with the algorithm synthetic deformation sequences for simple boundary conditions and try in a specific case study to match the resulting synthetics with the available observational and experimental data.

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Section: Ferences: (1) Suppe's Model Is Not Based On Kinematic Transfmentioning

confidence: 99%

Kinematic modeling of cross‐sectional deformation sequences by computer simulation

Contreras¹,

Suter²

1990

J. Geophys. Res.

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“…The Little Elbow duplex comprises fault-repeated Cambrian Eldon to basal Palliser strata exposed in the north part of the study area. The overlying Elbow multiduplex comprises closely faulted Palliser strata exposed from near the south boundary passes over the top of the ramp, and then partially unfolding as the next fault slice is emplaced beneath it (Boyer and Elliott, 1982;Mitra and Boyer, 1986;Mitra, 1986;Groshong and Usdansky, 1988;Cruikshank et al, 1989). In this model, the roof fault is only active in front of the active fault slice(s) and special geometric conditions are required for the formation of plane-roofed duplexes.…”

Section: Geological Settingmentioning

confidence: 97%

Large-scale duplex structures in the McConnell thrust sheet, Rocky Mountains, Southwest Alberta

McMechan

2001

Bulletin of Canadian Petroleum Geology

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Duplex fault zones are well exposed over a 40 km strike length in the far-travelled (40 km displacement) McConnell thrust sheet southwest of Calgary, Alberta. Two levels of duplex faulting, separated by a shared detachment, have formed. The McConnell Thrust forms the floor of the lower (Little Elbow) duplex. In this duplex, faults ramp across 800 m of carbonate section from glide zones in the Cambrian to a glide zone near the base of the Upper Devonian Palliser Formation, and trailing fault slices are folded over leading fault slices to form a folded, bumpy roof thrust. The exposed geometry is consistent with the ramp anticline model of thrust displacement and duplex formation. The roof of the Little Elbow duplex is also the floor of the overlying Elbow multiduplex, formed within carbonates of the 230 m thick Palliser Formation. The Elbow multiduplex consists of over twenty distinct duplexes comprising imbricate fault slices and separated by subsidiary roof and floor thrusts. The smooth, knife-sharp roof thrust of the multiduplex has folded somewhat independently of the floor, and has truncated, most likely by progressive shearing, underlying duplex structures. The duplex appears to have been enclosed within active roof and floor thrusts along its entire length and to have had simultaneous motion on many link faults. The overall geometry of the Elbow multiduplex changes along strike from a tight antiformal pod to a broadly folded sheet as a result of spacial variations in the stacking, folding, and shortening of component duplexes. Shortening within the Elbow multiduplex increases from near zero at its southeast termination to at least 12 km in the northcentral part of the study area.Both the Elbow multiduplex and the Little Elbow duplex formed by progressive tectonic erosion in the footwall of the "initial" McConnell Thrust. The "initial" McConnell Thrust, now represented by the roof thrust of the Elbow multiduplex, formed before the multiduplex, and eastward translation continued along it until the end of duplex formation. The Little Elbow duplex postdates the initial formation of the Elbow multiduplex and signals the initiation of two levels of duplex faulting and a stratigraphically lower position of the McConnell Thrust. Simultaneous motion on the "initial" McConnell Thrust, the shared detachment between the two duplexes, and the stratigraphically lower position of the McConnell Thrust allowed the simultaneous deformation of the Little Elbow duplex and Elbow multiduplex to occur in the same vertical section. Motion on the "initial" McConnell Thrust ended when the present McConnell Thrust was established as the dominant thrust. The Elbow multiduplex and the Little Elbow duplex end abruptly to the northwest at nearly coincident lateral ramps in the hanging wall of the "initial" McConnell Thrust and the present McConnell Thrust, respectively. Strain caused by an abrupt lateral change in fault displacement partitioning at the northwest end of the duplexes resulted in right-lateral displacement along and contrast...

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