Evidence for flexural shear folding associated with extensional faults

Higgs, W.G.; Williams, G. D.; Powell, C. M.

doi:10.1130/0016-7606(1991)103<0710:effsfa>2.3.co;2

Cited by 26 publications

(11 citation statements)

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“…Wernicke & Burchfiel 1982;White et al 1986;Dula 1991 ;Xiao & Suppe 1992;White 1992) and outcrops ( Fig. 7; Higgs et al 1991) indicate that, 2 'Rigid-body rotation' implies no internal deformation of a fault-bounded mass of rock. However, this condition typically is assumed, rather than documented, especially on seismic sections.…”

Section: Observations Of Natural Deformationmentioning

confidence: 94%

A critique of techniques for modelling normal-fault and rollover geometries

Hauge

Gray

1996

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A review of the published literature indicates that antithetic oblique shear, at an angle of 30 ___ 10 ~ measured from the vertical, is the most appropriate algorithm for quantitative modelling of geometric relationships between downward-flattening normal faults and the strata in their hanging walls. This conclusion is based on 2D analysis of 11 natural examples (listric normal faults without apparent salt involvement, shale mobility, or footwall deformation) and selected laboratory physical models. It may not apply where mobile salt, mobile shale, or significant footwall tilting or deformation is present. Antithetic oblique shear, like all modelling algorithms, does not accurately simulate natural deformation processes, which are significantly more complex.Exploration for and production of hydrocarbons in extensional settings requires accurate interpretation of faults and the strata they offset. This paper addresses the problem of how to select a modelling algorithm I for use in quantitative structural analysis of a normal fault and the strata in its hanging wall.

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Section: Observations Of Natural Deformationmentioning

confidence: 94%

A critique of techniques for modelling normal-fault and rollover geometries

Hauge

Gray

1996

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“…These two faults, in combination with the master fault, create a fanning pattern. Higgs et al (1991) described a similar fault-fanning pattern associated with a change in the dip of a prominent splay of the Sevier (Basin and Range) fault near Mount Carmel in southern Utah. The dip change in the graben-bounding fault at the Cascabel site coincides with the base of the 3-m-thick pink sandstone marker bed in the footwall and probably reflects a change in mechanical properties of the dominantly conglomeratic Quiburis succession.…”

Section: Outcrop Observationsmentioning

confidence: 84%

Fault and fault-rock characteristics associated with Cenozoic extension and core-complex evolution in the Catalina-Rincon region, southeastern Arizona

Davis¹,

Constenius²,

Dickinson³

et al. 2004

Geo. Society Am. Bull.

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Cenozoic extensional deformation in southern Arizona included (1) a Neogene phase of Basin and Range deformation recorded by high-angle normal faults and (2)an earlier phase of detachment faulting and brittle-ductile crustal shearing associated with tectonic denudation of metamorphic core complexes. In the Catalina-Rincon region, exposed fault zones produced at different crustal depths during successive extensional episodes display differing fault geometries and types of fault rocks formed during progressive crustal extension. Detachment faults are associated with both mylonites produced by ductile shear and cataclasites produced by brittle shear. Younger faults formed at shallower depths are associated with less intense cataclastic deformation and with brittle fracturing that includes transtensile phenomena at the shallowest crustal levels represented. Qualitative measures of net displacement along individual fault zones are provided by (1) the nature of contrasts among successively overprinted fabrics and internal structures in the footwall and (2) the degree of contrast between fabrics and structures of footwall and hanging-wall rocks. Footwalls of the oldest structures display varied brittle overprints of ductile fabrics and are juxtaposed across gouge zones along detachment surfaces with stratal successions cut by multiple brittle shear surfaces. Footwalls † of younger structures formed at shallower depths display multiple generations of cataclastic features, including brecciation of variable intensity and cataclasite dikes, but are juxtaposed against hanging-wall strata that are only moderately deformed by subsidiary faults. The shallowest fault zones lack either structural overprints in their footwalls or any significant contrasts between footwall and hanging-wall deformation. Exposures of mid-crustal rocks within the core complexes reflect successive exhumation and uplift of fault footwalls during sequential episodes of deformation. The present high elevation of mylonitic rocks in the Catalina-Rincon metamorphic core complex reflects dip slip and isostatic footwall flexure during Basin and Range deformation as well as tectonic denudation during detachment faulting. Net uplift of core rocks resulted from multiple phases of deformation.

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“…Flexural slip deformation is believed to work most effectively when the direction of maximum applied stress is subparallel to bedding and units of contrasting strength are present (e.g., compressional shortening of multi-layered sequences). Although flexural slip is usually associated with contractional deformation, several authors have suggested it is also an important kinematic control on extensional structures (Higgs et al, 1991;Ferrill et al, 1998;Rowan et al, 2003). In contractional folds, it is almost universally directed towards the anticlinal hinge.…”

Section: Flexural Hybrid (Shearing-slip) Kinematic Modelmentioning

confidence: 99%

Flexural Shear Associated with Transpressional Folding of Abu Dhabi Onshore Fields

Noufal

Agrab

Satti

et al. 2015

Day 1 Mon, November 09, 2015

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The Abu Dhabi onshore Anticlinal Fields are trending NE-SW and N-S, with their eastern flanks being of steeper dip (~3°-5°) than their western flanks (~1°-2°). In previous research, kinematics, and mechanics of onshore Abu Dhabi folded anticlines had not been addressed. The main objective of this paper is to understand the kinematics and mechanics of the folding systems.A new approach to understanding the mechanical evolution of these anticlines is presented here through the use of conceptual modelling and theoretical approaches. A combination of geological and geophysical tools is used for determining the direction of the shear stresses along the flexural slip planes. Although textural evidence, such as karstification and diagenesis, suggests local material redistribution on different scales, compositional trends support negligible volume flux at the scale of the anticlines. The preservation of bed length and bed thickness in most of the onshore Abu Dhabi Anticlines requires the development of bed-parallel shear. Abu Dhabi Anticlinal fields are mechanically evolved by flexural shear and flexural slip folding, which is characterized by differential simple shear along the bedding planes, where deformation is concurrent with the diagenesis. The layered horizons of these folds are mostly of carbonates, where the competency contrast is low and the friction between the layers is high leading to flexural shear. In the locations, where incompetent shale layers alternate with the carbonates, flexural slip is considered -although this is very limited within Abu Dhabi anticlinal structures. In these folds, the bedding planes of less competent layers act as boundaries of shear zones. Therefore, most of the internal deformation occurs within the less competent layers by partial recrystallization and development of fractures. However, the competent layers undergo pressure solution, development of sigmoidal extensional fissures, and stylolites in most cases. Thus, the overall folding system is heterogeneous and the competent layers simply slide over one another. The dominant direction of the over-riding shear is directed toward the fold axial surface and the stresses are released along the bedding plane discontinuities. The bedding plane discontinuities are considered to represent the finite neutral surface of the fold. Folds having parallel geometrical forms have opposite directions of structural shear in transtensional and transpressional regime.In the Abu Dhabi flexural slip shear folds, deformation in the hinge zone is characterized by pure shear, and deformation on fold limbs is characterized by components of both simple and pure shear. Strain models of pure bending, layer-parallel shear, and shear parallel to the hinge plane are shown to be the main mechanism of these folds. Preservation of these will play an important role in revealing a new play concept for the Abu Dhabi fields.

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Evidence for flexural shear folding associated with extensional faults

Cited by 26 publications

References 0 publications

A critique of techniques for modelling normal-fault and rollover geometries

A critique of techniques for modelling normal-fault and rollover geometries

Fault and fault-rock characteristics associated with Cenozoic extension and core-complex evolution in the Catalina-Rincon region, southeastern Arizona

Flexural Shear Associated with Transpressional Folding of Abu Dhabi Onshore Fields

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