Compositional and fluid pressure controls on the state of stress on the Nankai subduction thrust: A weak plate boundary

Brown, Kevin M.; Kopf, Achim J; Underwood, Michael B.; Weinberger, J. L.

doi:10.1016/s0012-821x(03)00388-1

Cited by 183 publications

(194 citation statements)

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“…This is consistent with several studies that have documented the important role of gouge composition-and clay content in particular-on frictional properties [e.g., Lupini et al, 1981;Logan and Rauenzahn, 1987;Brown et al, 2003;Ikari et al, 2009]. In other cases, fault weakness arises from a combination of shear fabric and phyllosilicate content [e.g., Collettini et al, 2009Collettini et al, , 2011Haines et al, 2013;Warr et al, 2014].…”

Section: 1002/2015jb011963supporting

confidence: 90%

Frictional properties of the active San Andreas Fault at SAFOD: Implications for fault strength and slip behavior

2015

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We present results from a comprehensive laboratory study of the frictional strength and constitutive properties for all three active strands of the San Andreas Fault penetrated in the San Andreas Observatory at Depth (SAFOD). The SAFOD borehole penetrated the Southwest Deforming Zone (SDZ), the Central Deforming Zone (CDZ), both of which are actively creeping, and the Northeast Boundary Fault (NBF). Our results include measurements of the frictional properties of cuttings and core samples recovered at depths of ~2.7 km. We find that materials from the two actively creeping faults exhibit low frictional strengths (μ = ~0.1), velocity‐strengthening friction behavior, and near‐zero or negative rates of frictional healing. Our experimental data set shows that the center of the CDZ is the weakest section of the San Andreas Fault, with μ = ~0.10. Fault weakness is highly localized and likely caused by abundant magnesium‐rich clays. In contrast, serpentine from within the SDZ, and wall rock of both the SDZ and CDZ, exhibits velocity‐weakening friction behavior and positive healing rates, consistent with nearby repeating microearthquakes. Finally, we document higher friction coefficients (μ > 0.4) and complex rate‐dependent behavior for samples recovered across the NBF. In total, our data provide an integrated view of fault behavior for the three active fault strands encountered at SAFOD and offer a consistent explanation for observations of creep and microearthquakes along weak fault zones within a strong crust.

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Section: 1002/2015jb011963supporting

confidence: 90%

Frictional properties of the active San Andreas Fault at SAFOD: Implications for fault strength and slip behavior

2015

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“…San Andreas Fault; Zoback et al, 1987). Moreover, depending on the amount of clay minerals in the fault core, the coefficient of friction may be significantly lower than 0.6 (Saffer et al, 2001;Brown et al, 2003;Collettini et al, 2009a;Lockner et al, 2011). Laboratory experiments on slipping zones rocks sampled on exhumed low-angle normal fault zones (e.g.…”

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 specific crystallographic orientation of chlorite could represent preferential sliding horizon controlled by its low frictional properties. Brown et al (2003) suggest that the internal chlorite friction coefficient along (001) plane is 0.26. Therefore the presence of chlorite along shear veins and their preferential orientation with (001) parallel to shear acts as a weakening process and would favours Monte Perdido fault creeping.…”

Section: Role Of Phyllosilicates On Fault Reactivationmentioning

confidence: 99%

Microtextural investigation (SEM and TEM study) of phyllosilicates in a major thrust fault zone (Monte Perdido, southern Pyrenees): impact on fault reactivation

et al. 2012

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Thrusting fault zone in foreland basins are characterized by highly foliated zones generally enriched in phyllosilicates which can play a major role on the mechanical behaviour of the fault. In this context, investigations of synkinematic clay minerals permit to determine the origin of the fluid from which they precipitated as well as the mechanisms of deformation. Our study is focused on clay mineral assemblages (illite and chlorite) in a major thrust fault located in the Monte Perdido massif (southern Pyrenees), a shallow thrust that affects upper cretaceouspaleocene platform carbonates and lower Eocene marls and turbidites. It implied 3 km of displacement of the Monte Perdido thrust unit with respect to the underlying Gavarnie unit. In this area the cleavage development by pressuresolution is linked to the Monte Perdido and Gavarnie thrust activity. The core zone of the fault, about 6 m thick, consists of an interval of intensely deformed clay-bearing rocks bounded by major shear surfaces. The deformed sediment is markedly darker than the protolith. Calcitequartz shear veins along the shear planes are abundant. Detailed SEM and TEM observations of highly deformed fault zone samples indicate that clay mineral enrichment in the core zone of the fault is not only related to passive increase by pressure-solution mechanism but that dissolution-recrystallization of phyllosilicates occurs during deformation. A mineral segregation is observed in the highly deformed zone. Newly formed 2M 1 muscovite is present along the cleavage whereas IIb chlorite crystals fill S V 2 shear veins suggesting syntectonic growth of phyllosilicates in the presence of fluids in low-grade metamorphic conditions. These mineralogical reactions act as weakening processes and would favour Monte Perdido fault creeping.

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Compositional and fluid pressure controls on the state of stress on the Nankai subduction thrust: A weak plate boundary

Cited by 183 publications

References 50 publications

Frictional properties of the active San Andreas Fault at SAFOD: Implications for fault strength and slip behavior

Frictional properties of the active San Andreas Fault at SAFOD: Implications for fault strength and slip behavior

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

Microtextural investigation (SEM and TEM study) of phyllosilicates in a major thrust fault zone (Monte Perdido, southern Pyrenees): impact on fault reactivation

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