Cataclasis and processes of particle size reduction

Blenkinsop, Thomas G.

doi:10.1007/bf00878888

Cited by 180 publications

(163 citation statements)

References 27 publications

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“…SAMMIS et al, 1987;BLENKINSOP, 1991;STORTI et al, 2003), in synthetic fault gouge generated in laboratory experiments (MARONE and SCHOLZ, 1989;BIEGEL et al, 1989) and have also been reproduced in numerical models (ABE and MAIR, 2005;MAIR and ABE, 2008). Theoretical models of grain fragmentation in sheared granular gouge (SAMMIS et al, 1987;SAMMIS and KING, 2007) indicate that progressive intra(trans)-granular fracture, that is most likely for nearest neighbour grains of similar sizes, can drive the evolution of the grain size distribution to a power law with an exponent of D = 2.6 at small strains and D = 3.0 at high strains.…”

Section: Introductionmentioning

confidence: 99%

“…STORTI et al, 2007;HEILBRONNER and KEULEN, 2006;STÜ NITZ et al, 2010) and grain size distributions (e.g. SAMMIS et al, 1987;BLENKINSOP, 1991;RAWLING and GOODWIN, 2003;STORTI et al, 2003;BILLI, 2005;KEULEN et al, 2007;SAMMIS and KING, 2007) of the gouge grains. One feature that many fault gouges have in common is that the grain size distribution follows a power law.…”

Section: Introductionmentioning

confidence: 99%

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Breaking Up: Comminution Mechanisms in Sheared Simulated Fault Gouge

Mair

Abe

2011

Pure Appl. Geophys.

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Abstract-The microstructural state and evolution of fault gouge has important implications for the mechanical behaviour, and hence the seismic slip potential of faults. We use 3D discrete element (DEM) simulations to investigate the fragmentation processes operating in fault gouge during shear. Our granular fault gouge models consist of aggregate grains, each composed of several thousand spherical particles stuck together with breakable elastic bonds. The aggregate grains are confined between two blocks of solid material and sheared under a given normal stress. During shear, the grains can fragment in a somewhat realistic way leading to an evolution of grain size, grain shape and overall texture. The 'breaking up' of the fault gouge is driven by two distinct comminution mechanisms: grain abrasion and grain splitting. The relative importance of the two mechanisms depends on applied normal stress, boundary wall roughness and accumulated shear strain. If normal stress is sufficiently high, grain splitting contributes significantly to comminution, particularly in the initial stages of the simulations. In contrast, grain abrasion is the dominant mechanism operating in simulations carried out at lower normal stress and is also the main fragmentation mechanism during the later stages of all simulations. Rough boundaries promote relatively more grain splitting whereas smooth boundaries favor grain abrasion. Grain splitting (plus accompanying abrasion) appears to be an efficient mechanism for reducing the mean grain size of the gouge debris and leads rapidly to a power law size distribution with an exponent that increases with strain. Grain abrasion (acting alone) is an effective way to generate excess fine grains and leads to a bimodal distribution of grain sizes. We suggest that these two distinct mechanisms would operate at different stages of a fault's history. The resulting distributions in grain size and grain shape may significantly affect frictional strength and stability. Our results therefore have implications for the earthquake potential of seismically active faults with accumulations of gouge. They may also be relevant to the susceptibility of rockslides since non-cohesive basal shear zones will evolve in a similar way and potentially control the dynamics of the slide.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Breaking Up: Comminution Mechanisms in Sheared Simulated Fault Gouge

Mair

Abe

2011

Pure Appl. Geophys.

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“…Blenkinsop (1991) and 609 that this is the material, which is created by the rupture process during the seismic event, 637 while the higher surface density of gouge is due to the combined effect of fracturing and 638 subsequent deformation during slip. 639…”

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confidence: 99%

Grain size distributions of fault rocks: A comparison between experimentally and naturally deformed granitoids

Keulen

Heilbronner

Stünitz

et al. 2007

Journal of Structural Geology

140

101

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“…Blenkinsop (1991) determined PSD ranging from 1.88-3.08 in naturally fragmented rock, higher where alteration also played a role. D increase with strain.…”

Section: General Distribution Of Particle Sizes and Relation To Mechamentioning

confidence: 99%