The kinematics of gouge deformation

Sammis, Charles G.; King, Geoffrey; Biegel, Ronald L.

doi:10.1007/bf00878033

Cited by 588 publications

(439 citation statements)

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“…[1993]. The distribution in the gouge and breccia from the Lopez Canyon fault from Sammis et al [1987] is also shown for comparison. Note the fall-off in particle density for the larger particles in the sample adjacent to the fault core.…”

Section: Nearest Neighbor Model For Fragmentation During Flowmentioning

confidence: 99%

“…The gouge and breccia is generally non-cohesive, usually shows no sign of significant shear strain, and also tends to have a power-law size distribution, but with a mass dimension closer to D 2 = 1.6 [Sammis et al, 1987]. Particle distributions in cataclasite and gouge are compared in Figure 1.…”

Section: Introductionmentioning

confidence: 99%

“…[6] To explain the self-similarity found in low strain gouge and breccia, Sammis et al [1987] proposed a ''constrained comminution'' model in which the observed dimension D 2 = 1.6 is a direct consequence of a particle's fracture probability being controlled by the relative size of its nearest neighbors. This model differs from those that describe commercial crushing and milling operations in which a particle's fracture probability is determined by its distribution of starter flaws, usually assumed to be Poissonian, and which results in exponential particle distributions [Prasher, 1987].…”

Section: Introductionmentioning

confidence: 99%

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Mechanical origin of power law scaling in fault zone rock

Sammis

King

2007

Geophysical Research Letters

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[1] A nearest neighbor fragmentation model, previously developed to explain observations of power law particle distributions in 3D with mass dimension D 3 % 2.6 (D 2 % 2.6 in 2D section) in low-strain fault gouge and breccia, is extended to the case of large strains to explain recent observations of D 3 % 3.0 (D 2 % 2.0 in 2D section) in the highly strained cores of many exhumed fault zones. At low strains, the elimination of same-sized nearest neighbors has been shown to produce a power law distribution which is characterized by a mass dimension near D 3 % 2.6. With increasing shear strain these isolated same-size neighbors can collide, in which case one of them fractures. The probability of two same size neighbors colliding and fragmenting in a simple shear flow is a function of the size and density of the two particles. Only for a power law distribution with D 3 = 3.0 is this collision probability independent of the size of the particles.

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Section: Nearest Neighbor Model For Fragmentation During Flowmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Mechanical origin of power law scaling in fault zone rock

Sammis

King

2007

Geophysical Research Letters

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“…Relative particle abundances were determined according to the following power law relationship [e.g., Sammis et al, 1986Sammis et al, , 1987 …”

Section: Design Of Numerical Experimentsmentioning

confidence: 99%

Numerical simulations of granular shear zones using the distinct element method: 1. Shear zone kinematics and the micromechanics of localization

Morgan¹,

Boettcher²

1999

J. Geophys. Res.

245

218

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Abstract. Two-dimensional numerical simulations were conducted using the distinct element method (DEM) to examine the influences of particle size distribution (PSD) and interparticle friction /at, on the nature of deformation in granular fault gouge. Particle fracture was not allowed in this implementation but points in PSD space were examined by constructing assemblages of particles with self-similar size distributions defined by the twodimensional power law exponent D. For these numerical "experiments," D ranged from 0.81 to 2.60, where D = 1.60 represents the two-dimensional equivalent of a characteristic PSD to which cataclastically deforming gouge is thought to evolve. Experiments presented here used /at, values of 0.10 and 0.50 and were conducted using normal stress c• n on the shear zone walls of 70 MPa. Shear strain within these simulated assemblages was accommodated by intermittent displacement along discrete slip surfaces, alternating between broadly distributed deformation along multiple slip planes and highly localized deformation along a single, sharply defined, subhorizontal zone of slip. Slip planes corresponded in orientation and sense of shear to shear structures observed in natural gouge zones, specifically Riedel and Y shears; the oblique Riedel shears showed more extreme orientations than typical, but their geometries were consistent with those predicted for lowstrength Coulomb materials. The character of deformation in the shear zone varied with PSD due to changes in the relative importance of interparticle slip and rolling as deformation mechanisms. A high degree of frictional coupling between large rolling particles in low D (coarse-grained) assemblages resulted in wide zones of slip and broadly distributed deformation. In higher D assemblages (D >= 1.60), small rolling particles selforganized into columns that separated large rolling particles, causing a reduction in frictional resistance within the deforming assemblage. This unusual particle configuration appears to depend on a critical abundance of small particles achieved at D = 1.60 and may enable strain localization in both real and simulated granular assemblages.

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“…This shows quantitatively the gradient of anisotropy from the gouge material inside the fault to the much more anisotropic peripheral fractured zones. This result highlights the differences between fracture and fragmentation processes: while fractures are initiated locally under tension (mode I) with opening much smaller than fracture length, i.e., characterized by a strong anisotropy, fragmentation under shear is a complex multiscale process involving friction, grain rotation and comminution (e.g., [11][12][13][14]) that leads to relatively isotropic grain shapes. The present analysis clearly reveals this transition from one mechanism to another across the fault plane.…”

Section: Discussionmentioning

confidence: 95%

Analysis of image vs. position, scale and direction reveals pattern texture anisotropy

et al. 2015

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Pattern heterogeneities and anisotropies often carry significant physical information. We provide a toolbox which: (i) cumulates analysis in terms of position, direction and scale; (ii) is as general as possible; (iii) is simple and fast to understand, implement, execute and exploit. It consists in dividing the image into analysis boxes at a chosen scale; in each box an ellipse (the inertia tensor) is fitted to the signal and thus determines the direction in which the signal is more present. This tensor can be averaged in position and/or be used to study the dependence with scale. This choice is formally linked with Leray transforms and anisotropic wavelet analysis. Such protocol is intuitively interpreted and consistent with what the eye detects: relevant scales, local variations in space, privileged directions. It is fast and parallelizable. Its several variants are adaptable to the users' data and needs. It is useful to statistically characterize anisotropies of 2D or 3D patterns in which individual objects are not easily distinguished, with only minimal pre-processing of the raw image, and more generally applies to data in higher dimensions. It is less sensitive to edge effects, and thus better adapted for a multiscale analysis down to small scale boxes, than pair correlation function or Fourier transform. Easy to understand and implement, it complements more sophisticated methods such as Hough transform or diffusion tensor imaging. We use it on various fracture patterns (sea ice cover, thin sections of granite, granular materials), to pinpoint the maximal anisotropy scales. The results are robust to noise and to users choices. This toolbox could turn also useful for granular materials, hard condensed matter, geophysics, thin films, statistical mechanics, characterization of networks, fluctuating amorphous systems, inhomogeneous and disordered systems, or medical imaging, among others.

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The kinematics of gouge deformation

Cited by 588 publications

References 16 publications

Mechanical origin of power law scaling in fault zone rock

Mechanical origin of power law scaling in fault zone rock

Numerical simulations of granular shear zones using the distinct element method: 1. Shear zone kinematics and the micromechanics of localization

Analysis of image vs. position, scale and direction reveals pattern texture anisotropy

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