The mechanical feasibility of low-angle normal faulting

Westaway, Rob

doi:10.1016/s0040-1951(99)00148-1

Cited by 87 publications

(82 citation statements)

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“…Wills & Buck (1997) examined the possible role of stress-field rotation in the development of rooted detachment faults, and concluded that applied stresses are not in general sufficient to create low-angle normal faults that would propagate to the Earth's surface (cf. Westaway 1999). There will be no one-size-fits-all solution.…”

Section: Discussionmentioning

confidence: 99%

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Observations from the Basin and Range Province (western United States) pertinent to the interpretation of regional detachment faults

Christie‐Blick

Anders

Wills

et al. 2007

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This paper summarizes the results of completed and ongoing research in three areas of the Basin and Range Province of the western United States that casts doubt on the interpretation of specific regional detachment faults and the large extensional strains with which such faults are commonly associated. Given that these examples were influential in the development of ideas about low-angle normal faults, and particularly in making the case for frictional slip at dips of appreciably less than the 308 lock-up angle for m 0.6 (where m is the coefficient of friction), we advocate a critical re-examination of interpreted detachments elsewhere in the Basin and Range Province and in other extensional and passive margin settings.The Sevier Desert 'detachment' of west-central Utah is reinterpreted as a Palaeogene unconformity that has been traced to depth west of the northern Sevier Desert basin along an unrelated seismic reflection (most probably a splay of the Cretaceous-age Pavant thrust). The absence of evidence in well cuttings and cores for either brittle deformation (above) or ductile deformation (below) is inconsistent with the existence of a fault with as much as 40 km of displacement. The Pavant thrust and the structurally higher Canyon Range thrust are erosionally truncated at the western margin of the southern Sevier Desert basin, and are not offset by the 'detachment' in the manner assumed by those inferring large extension across the basin.The Mormon Peak detachment of SE Nevada is reinterpreted as a series of slide blocks on the basis of detachment characteristics and spatially variable kinematic indicators that are more closely aligned with the modern dip direction than the inferred regional extension direction. A particularly distinctive feature of the detachment is a basal layer of up to several tens of centimetres of polymictic conglomerate that was demonstrably involved in the deformation, with clastic dykes of the same material extending for several metres into overlying rocks in a manner remarkably similar to that observed at rapidly emplaced slide blocks. The Castle Cliff detachment in the nearby Beaver Dam Mountains of SW Utah is similarly regarded as a surficial feature, as originally interpreted, and consistent with its conspicuous absence in seismic reflection profiles from the adjacent sedimentary basin.The middle Miocene Eagle Mountain Formation of eastern California, interpreted on the basis of facies evidence and distinctive clast provenance to have been moved tectonically more than 80 km ESE from a location close to the Jurassic-age Hunter Mountain batholith of the Cottonwood Mountains, is reinterpreted as having accumulated in a fluvial-lacustrine rather than alluvial fanlacustrine setting, with no bearing on either the amount or direction of tectonic transport. The conglomeratic rocks upon which the provenance argument was based are pervasively channelized, with erosional relief of less than 1 m to as much as 15 m, fining-upwards successions at the same scale and abundant trough ...

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Section: Discussionmentioning

confidence: 99%

“…Axen , 1999cf. Axen , 2004Scott & Lister 1992;Axen & Selverstone 1994;Wernicke 1995;Rietbrock et al 1996;Abers et al 1997;Westaway 1999;Sorel 2000;Collettini & Barchi 2002;Hayman et al 2003).…”

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Observations from the Basin and Range Province (western United States) pertinent to the interpretation of regional detachment faults

Christie‐Blick

Anders

Wills

et al. 2007

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“…The non-Andersonian concept of low-angle normal faulting has raised persistent questions regarding how they are generated and how they overcome the expected high frictional resistance to slip (Wernicke, 1981;Westaway, 1999;Zheng et al, 2004;Axen, 2004). Interestingly, frictional effects along the SNSZ have been implicated as a heat source sufficient to cause melting of shear zone schists producing leucogranite melts (Abdalla and Mohamed, 1999;Abd El-Naby and Frisch, 2006), and the leucogranites indeed have similar age to SNSZ shearing activity (Moghazi et al, 2004;Abd El-Naby and Frisch, 2006).…”

Section: What Were the Frictional Aspects Of The Snsz?mentioning

confidence: 99%

The Sha’it–Nugrus shear zone separating Central and South Eastern Deserts, Egypt: A post-arc collision low-angle normal ductile shear zone

Fowler

Osman

2009

Journal of African Earth Sciences

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“…The mechanical behaviour of low-angle normal faults (LANFs; dip angle < 30 • ) is a critical issue in fault mechanics (Jackson and White, 1989;Buck, 1993;Westaway, 1999;Collettini and Sibson, 2001;Collettini, 2011), and it represents a paradox if the paradigm of faulting in a brittle, elastic, homogenous crust holds. Frictional fault reactivation theory (Anderson, 1951;Sibson, 1985) predicts that in extensional settings the maximum principal stress is vertical and no motion is possible on faults dipping less than 30 • and sliding with a friction coefficient (µ s ) in the range of 0.6-0.85 (Byerlee, 1978).…”

Section: Introductionmentioning

confidence: 99%

On the mechanical behaviour of a low-angle normal fault: the Alto Tiberina fault (Northern Apennines, Italy) system case study

et al. 2016

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Abstract. Geological and seismological observations have been used to parameterize 2-D numerical elastic models to simulate the interseismic deformation of a complex extensional fault system located in the Northern Apennines (Italy). The geological system is dominated by the presence of the Alto Tiberina fault (ATF), a large (60 km along strike) lowangle normal fault dipping 20 • in the brittle crust (0-15 km). The ATF is currently characterized by a high and constant rate of microseismic activity, and no moderate-to-large magnitude earthquakes have been associated with this fault in the past 1000 years. Modelling results have been compared with GPS data in order to understand the mechanical behaviour of this fault and a suite of minor syn-and antithetic normal fault segments located in the main fault hanging wall.The results of the simulations demonstrate the active role played by the Alto Tiberina fault in accommodating the ongoing tectonic extension in this sector of the chain. The GPS velocity profile constructed through the fault system cannot be explained without including the ATF's contribution to deformation, indicating that this fault, although misoriented, has to be considered tectonically active and with a creeping behaviour below 5 km depth.The low-angle normal fault also shows a high degree of tectonic coupling with its main antithetic fault (the Gubbio fault), suggesting that creeping along the ATF may control the observed strain localization and the pattern of microseismic activity.

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The mechanical feasibility of low-angle normal faulting

Cited by 87 publications

References 113 publications

Observations from the Basin and Range Province (western United States) pertinent to the interpretation of regional detachment faults

Observations from the Basin and Range Province (western United States) pertinent to the interpretation of regional detachment faults

The Sha’it–Nugrus shear zone separating Central and South Eastern Deserts, Egypt: A post-arc collision low-angle normal ductile shear zone

On the mechanical behaviour of a low-angle normal fault: the Alto Tiberina fault (Northern Apennines, Italy) system case study

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