The behaviour of rigid triaxial ellipsoidal particles in viscous flows—modeling of fabric evolution in a multiparticle system

Ježek, Josef; Melka, Radek; Schulmann, Karel; Venera, Zdeněk

doi:10.1016/0040-1951(94)90027-2

Cited by 83 publications

(36 citation statements)

References 17 publications

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“…Because of their small size and their natural low shape anisotropy, the perpendicular long axis a, intermediate axis b and short axis c, that characterise the three-dimensional shape of each magnetite grain, cannot be determined with precision. In addition, although numerical simulations exist for triaxial rigid markers (Ježek et al, 1994;Hrouda and Ježek 1999), we use the most common theoretical and numerical models that are based on axisymmetric particles (Jeffery, 1922;Reed and Tryggvason, 1974;Willis, 1977). The aspect ratio ζ = a/c of the particles was measured in 30 randomly oriented sections of the frozen starting material.…”

Section: Starting Materialsmentioning

confidence: 99%

Magnetic and shape fabrics of magnetite in simple shear flows

Arbaret

Launeau

Diot

et al. 2013

Journal of Volcanology and Geothermal Research

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International audienceThe magnetite fabrics measured by anisotropy of magnetic susceptibility (AMS) and by shape preferred orientation (SPO) optical methods are classically used as flow kinematics indicators in lava flows. The development of magnetite fabrics during simple shear strains γ ≤ 20 was performed using a suspension of 1% volume fraction of multidomain magnetite randomly contained in a mixture of silicone and wax. We measured AMS fabric and SPO ellipsoids by calculating a quadratic shape tensor from oriented thin-sections. For γ < 8, fabrics obey to the theoretical model of rotation of Jeffery (1922). Fabrics are usable to determine the flow kinematics, including the amount of applied finite strain. For γ > 8, fabric elements, foliation and lineation, are stabilised closely parallel to the flow plane and the shear direction, respectively. Two- and three-dimensional numerical simulations using measured aspect ratios of magnetite point out that the large scattering of aspect ratios and the initial orientation distribution of particles are together responsible for a wide-ranging loss of periodicity. The stable AMS and SPO fabrics observed at large strains in experiments are the result of these primary fabric properties combined to collisions between particles and, possibly, their complex three-dimensional shapes. In addition, the constant angular relationship observed at large strains between fabrics and flow components is related to the transient collisions. Consequently, the determination of the lava flow kinematics by using fabric properties measured either by AMS or by SPO analyses should be indubitably associated to a detailed study of the three-dimensional shape of the solid carriers. Regularly shaped populations of low elongated particles will be capable to produce cyclic to oscillating fabrics, while the fabric of elongated particles will be more sensitive to the shape parameters and collisions, ultimately favouring stable fabrics at large strains

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Section: Starting Materialsmentioning

confidence: 99%

Magnetic and shape fabrics of magnetite in simple shear flows

Arbaret

Launeau

Diot

et al. 2013

Journal of Volcanology and Geothermal Research

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“…Jeffery, 1922), and another where the number of clasts is relatively high and inclusions interact. Inclusion interaction in multi-inclusion systems usually leads to tilling effects, which strongly affect inclusion rotation and can bring the inclusion to a stable equilibrium orientation (Arbaret et al, 1996;Fernandez et al, 1983;Ildefonse et al, 1992a,b;Jezek et al, 1994;Mandal et al, 2005;March, 1932;Tikoff and Teyssier, 1994). However, this stabilization mechanism is obviously not viable in cases of SPO defined by relatively isolated clasts.…”

Section: Inclusion Interactionmentioning

confidence: 99%

Applications of inclusion behaviour models to a major shear zone system: The Nordfjord-Sogn Detachment Zone in western Norway

Marques

Schmid

Andersen

2007

Journal of Structural Geology

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Rigid inclusion models have reached a stage where one should be able to use them to obtain quantitative values from ductile shear zones. We used natural data collected in three sites and combined analogue and theoretical modelling to assess vorticity, strain, nature of rigid inclusion/ matrix interface and confinement in the large-scale, ductile Nordfjord-Sogn Detachment Zone (NSDZ) of the Caledonides of western Norway. Our study shows that: (1) the observed shape preferred orientation (SPO) at higher structural levels of the NSDZ at Site 1, Gjervika, can be explained by simple shear (pure shear/simple shear ratio S r ¼ 0) associated with a slipping inclusion/matrix interface. (2) The observed SPO at deeper structural levels of the NSDZ at Site 2, near Sandane can be produced by simple shear associated with a significant amount of shortening across the shear zone (S r z 1), acting upon rigid inclusions in slipping contact with the enclosing matrix. The large scale extensional NSDZ under investigation shows evidence of strain partitioning: rocks vary from protomylonites to ultramylonites, and the simple shear and pure shear components are heterogeneously distributed. Therefore, we conclude that flow in the NSDZ was very heterogeneous both at the kilometre and the metre scale. However, the present study suggests that the amount of shortening across the shear plane throughout the NSDZ increases with depth, and the flattening component contributes to exhumation of the eclogite facies rocks in its footwall.

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“…For example, recent studies indicate that magmatic fabrics in plutons form in rheologically complex crystal-rich mushes, and reflect strain from a wide variety of processes including regional tectonic deformation (possibly unrelated to magma flow, emplacement, and shape of the pluton; e.g., Benn et al 2001;Callahan and Markley 2003;Paterson et al 1998Paterson et al , 2003). Moreover, two or more different subfabrics (multiple particle orientations resulting from a single process) may develop in a heterogeneous particle population during magmatic flow (e.g., Arbaret et al 2001;Ildefonse and Mancktelow 1993;Ildefonse et al 1992aIldefonse et al , b, 1997Ježek et al 1994Ježek et al , 1996Ježek et al , 1999Schulmann et al 1997), making it difficult to relate the bulk rock fabric or its components to the fracture orientation. Similarly, multiple magmatic fabrics can record different processes in a single pluton (Paterson et al 1998;Ž ák et al 2005), or there can be composite fabrics where a single magmatic fabric was formed by several superposed processes (Paterson et al 2003;.…”

Section: Introductionmentioning

confidence: 99%

“Granite tectonics” revisited: insights from comparison of K-feldspar shape-fabric, anisotropy of magnetic susceptibility (AMS), and brittle fractures in the Jizera granite, Bohemian Massif

Žák

Verner

Klomínský

et al. 2008

Int J Earth Sci (Geol Rundsch)

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In the Jizera granite of the Krkonoše-Jizera Plutonic Complex, northern Bohemian Massif, contrasting patterns of magmatic K-feldspar fabrics and brittle fractures characterize different structural levels of the pluton. The uppermost exposed level at *800-1,100 m above sea level is dominated by flat foliation that overprints two steep foliations. In contrast, K-feldspar shape-fabric in an underground tunnel (*660 m above sea level) shows complex variations in orientation and intensity. Magnetic fabric carried by coaxial contributions of biotite, magnetite, and maghemite is homogeneous along the examined section of the tunnel, and is decoupled from the K-feldspar fabric. The Jizera granite is crosscut by two regional sets of subvertical fractures (*NE-SW and *NW-SE) and by near-surface exfoliation joints. The multiple fabrics are inferred to reflect a complex magmatic strain history at different structural levels of the pluton, bearing little or no relationship to the fracture network. In contrast to the original concept of Hans Cloos (''granite tectonics''), we conclude that no simple genetic relationship exists between fabrics and fractures in plutons. An alternative classification of fractures in plutons thus should avoid relationships to magmatic fabrics and should instead consist of cooling, syntectonic, uplift, and post-uplift fractures.

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The behaviour of rigid triaxial ellipsoidal particles in viscous flows—modeling of fabric evolution in a multiparticle system

Cited by 83 publications

References 17 publications

Magnetic and shape fabrics of magnetite in simple shear flows

Magnetic and shape fabrics of magnetite in simple shear flows

Applications of inclusion behaviour models to a major shear zone system: The Nordfjord-Sogn Detachment Zone in western Norway

“Granite tectonics” revisited: insights from comparison of K-feldspar shape-fabric, anisotropy of magnetic susceptibility (AMS), and brittle fractures in the Jizera granite, Bohemian Massif

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