Normal faults, normal friction?

Collettini, Cristiano; Sibson, Richard H.

doi:10.1130/0091-7613(2001)029<0927:nfnf>2.0.co;2

Cited by 250 publications

(195 citation statements)

References 25 publications

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“…Buck, 1988) and constraints from faulting mechanics. The relative lack of seismicity along shallow dipping normal faults is also a well-documented characteristic of continental detachments (Collettini and Sibson, 2001;Jackson and White, 1989) and global seismicity compilations (e.g., Wernicke, 1995).…”

Section: Discussionmentioning

confidence: 99%

Experimental and seismological constraints on the rheology, evolution, and alteration of the lithosphere at oceanic spreading centers

deMartin¹

2007

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Oceanic spreading centers are sites of magmatic, tectonic, and hydrothermal processes. In this thesis I present experimental and seismological constraints on the evolution of these complex regions of focused crustal accretion and extension. Experimental results from drained, triaxial deformation experiments on partially molten olivine reveal that melt extraction rates are linearly dependent on effective mean stress when the effective mean stress is low and non-linearly dependent on effective mean stress when it is high. Microearthquakes recorded above an inferred magma reservoir along the TAG segment of the Mid-Atlantic Ridge delineate for the first time the arcuate, subsurface structure of a long-lived, active detachment fault. This fault penetrates the entire oceanic crust and forms the high-permeability pathway necessary to sustain long-lived, high-temperature hydrothermal venting in this region. Long-lived detachment faulting exhumes lower crustal and mantle rocks. Residual stresses generated by thermal expansion anisotropy and mismatch in the uplifting, cooling rock trigger grain boundary microfractures if stress intensities at the tips of naturally occurring flaws exceed a critical stress intensity factor. Experimental results coupled with geomechanical models indicate that pervasive grain boundary cracking occurs in mantle peridotite when it is uplifted to within 4 km of the seafloor. Whereas faults provide the high-permeability pathways necessary to sustain high-temperature fluid circulation, grain boundary cracks form the interconnected network required for pervasive alteration of the oceanic lithosphere. This thesis provides fundamental constraints on the rheology, evolution, and alteration of the lithosphere at oceanic spreading centers.

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Section: Discussionmentioning

confidence: 99%

Experimental and seismological constraints on the rheology, evolution, and alteration of the lithosphere at oceanic spreading centers

deMartin¹

2007

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“…Froitzheim & Eberli 1990;Lister et al 1991;Reston et al 1996;Driscoll & Karner 1998;Hodges et al 1998;Osmundsen et al 1998;Taylor et al 1999;Boncio et al 2000;Manatschal et al 2001;Canales et al 2004). However, the apparent conflict between generally accepted geological interpretations and rock mechanical and seismological considerations has yet to be resolved satisfactorily (Sibson 1985;Jackson 1987;Jackson & White 1989;Collettini & Sibson 2001;Scholz & Hanks 2004;cf. Axen 1992cf.…”

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confidence: 99%

“…Beginning in the early 1990s, we became interested in Basin and Range examples for which evidence was regarded by the structural geological community to be the most compelling for slip at dips of appreciably less than 308 -the lowest plausible frictional lock-up angle for crustally rooted normal faults in the absence of unusual materials (m , 0.6, where m is the coefficient of friction) (Sibson 1985;Collettini & Sibson 2001) -and for the very large extensional strains with which low-angle normal faults are commonly associated Levy & ChristieBlick 1989;Snow & Wernicke 2000). We reasoned that if progress was to be made in developing a better theoretical understanding, it would be useful to focus on geological examples providing the firmest constraints.…”

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confidence: 99%

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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“…Because the lock-up angle depends on the critical b / eff for rupture, measurements of lock-up angle can be used to estimate that b / eff . This has been done using compilations of dip angles of seismically active dip-slip faults [Sibson, 1994;Sibson and Xie, 1998;Collettini and Sibson, 2001], revealing a general agreement with Byerleelevel ratios of shear to effective normal stress.…”

Section: Introductionmentioning

confidence: 99%

Additional shear resistance from fault roughness and stress levels on geometrically complex faults

2013

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[1] The majority of crustal faults host earthquakes when the ratio of average background shear stress b to effective normal stress eff is b / eff 0.6. In contrast, mature plate-boundary faults like the San Andreas Fault (SAF) operate at b / eff 0.2. Dynamic weakening, the dramatic reduction in frictional resistance at coseismic slip velocities that is commonly observed in laboratory experiments, provides a leading explanation for low stress levels on mature faults. Strongly velocity-weakening friction laws permit rupture propagation on flat faults above a critical stress level pulse / eff 0.25. Provided that dynamic weakening is not restricted to mature faults, the higher stress levels on most faults are puzzling. In this work, we present a self-consistent explanation for the relatively high stress levels on immature faults that is compatible with low coseismic frictional resistance, from dynamic weakening, for all faults. We appeal to differences in structural complexity with the premise that geometric irregularities introduce resistance to slip in addition to frictional resistance. This general idea is quantified for the special case of self-similar fractal roughness of the fault surface. Natural faults have roughness characterized by amplitude-to-wavelength ratios˛between 10 -3 and 10 -2 . Through a second-order boundary perturbation analysis of quasi-static frictionless sliding across a band-limited self-similar interface in an ideally elastic solid, we demonstrate that roughness induces an additional shear resistance to slip, or roughness drag, given by drag = 8 3˛2 G * / min , for G * = G/(1 -) with shear modulus G and Poisson's ratio , slip , and minimum roughness wavelength min . The influence of roughness drag on fault mechanics is verified through an extensive set of dynamic rupture simulations of earthquakes on strongly rate-weakening fractal faults with elastic-plastic off-fault response. The simulations suggest that fault rupture, in the form of self-healing slip pulses, becomes probable above a background stress level b pulse + drag . For the smoothest faults (˛ 10 -3 ), drag is negligible compared to frictional resistance, so that b pulse 0.25 eff . However, on rougher faults (˛ 10 -2 ), roughness drag can exceed frictional resistance. We expect that drag ultimately departs from the predicted scaling when roughness-induced stress perturbations activate pervasive off-fault inelastic deformation, such that background stress saturates at a limit ( b 0.6 eff ) determined by the finite strength of the off-fault material. We speculate that this strength, and not the much smaller dynamically weakened frictional strength, determines the stress levels at which the majority of faults operate.Citation: Fang, Z., and E. M. Dunham (2013), Additional shear resistance from fault roughness and stress levels on geometrically complex faults,

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Normal faults, normal friction?

Cited by 250 publications

References 25 publications

Experimental and seismological constraints on the rheology, evolution, and alteration of the lithosphere at oceanic spreading centers

Experimental and seismological constraints on the rheology, evolution, and alteration of the lithosphere at oceanic spreading centers

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

Additional shear resistance from fault roughness and stress levels on geometrically complex faults

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