Bruce E Hobbs

Bruce E Hobbs
The Commonwealth Scientific and Industrial Research Organisation | CSIRO

BSc, PhD

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342
Publications
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10,527
Citations

Publications

Publications (342)
Article
The effect of deformation history on the development of crystallographic preferred orientation in quartzities has been simulated using a computer program based on the Taylor-Bishop-Hill analysis. Model quartzities with different combinations of glide systems have been subjected to various coaxial and non-coaxial deformation histories. It is possibl...
Article
The Taylor-Bishop-Hill model for polycrystalline deformation has been applied as the basis of a computer program for simulating the development of preferred crystallographic orientations in deforming rocks in which the predominant mode of deformation is dislocation glide within the grains. The model assumes homogeneous deformation on the scale of t...
Article
An experiment is described in which folds and an axial-plane foliation were produced in an artificial layered specimen made from salt and mica. The foliation differs on a micro-scale from natural foliations due to the unnatural experimental conditions. Taking results of annealing experiments into account a model is presented for the development of...
Article
Two types of anti-phase domain boundaries are found in kyanite. One type occurs on (220) with a fault vector R = ½ [111] and is related to the stacking of the close-packed planes in the distorted face-centred cubic oxygen lattice of kyanite. The other anti-phase domain boundary is on (100) and occurs in association with the super-dislocations of Bu...
Article
Specimens cut from a single synthetic quartz crystal and oriented normal to r( 101) were deformed in a gas apparatus at 3 kbar confining pressure and temperatures from 475° to 900° C. There was a large variation in stress—strain behaviour between specimens, which could be correlated with inhomogeneity in OH concentration as revealed by infrared abs...
Article
Partial syntectonic recrystallization has been produced in an experimentally deformed plagioclase (peristerite An4.5). The recrystallized grains are scattered through the strongly deformed matrix and appear to have developed by a nucleation and growth mechanism.
Article
An experimental study of the behaviour of micaceous aggregates undergoing deformation during and after mica growth has been undertaken using pelletised powder consisting of an oxide mix with the stoichiometry of phlogopite. The influences of temperature, pore fluid content, strain, strainrate, and pre-mixing time have been examined. It is concluded...
Article
Chemical and microstructural data from one experimentally and two naturally deformed and recrystallized micas are discussed in terms of established metallurgical mechanisms for strain-induced nucleation and growth during recrystallization. It is suggested that none of these nucleation mechanisms is applicable, and that nucleation is driven by energ...
Article
A maximum microline-low albite of 33 mole percent Or was prepared by alkali ion exchange at 1000 C and subsequently annealed in air at lower temperatures. The exsolution microstructure produced in these samples was studied by transmission electron microscopy. At or above 600 C the compositional difference of the coherent lamellae increases rapidly...
Article
Transmission electron microscopy, TEM, has been used to determine the micromechanisms of creep in peridotite experimentally deformed at 780–950°C and 3 Kb confining pressure. Both crystal plasticity and cataclastic flow are shown to be operative. A detailed study has revealed three major categories of cataclastic behaviour. They are (a) ‘clean’ mic...
Article
Single crystals of biotite have been shortened up to 20% in compression tests parallel to [100], [110] and [010] directions at 3 Kbar confining pressure and temperatures from 300 to 700 C, and at a strain rate of 10–4 sec–1. Thick metal constraining sleeves were used and led to a distribution of kinking throughout the crystals. The orientation of k...
Article
This paper discusses the deformation of fluids in which there is a nonlinear relationship between stress and deformation rate. These fluids comprise four classes, the general class containing the fluids in which the stress at a particular time is determined by the history of all deformed states before that time. These are called simple fluids. The...
Article
Transmission electron microscopy has been used to observe the dislocation substructures in a number of naturally deformed quartzites thinned by ion bombardment. The selected specimens exhibit the optical features that have been widely illustrated in the literature and that are characteristic of naturally deformed quartzites. By a comparison with ex...
Article
Full-text available
Single crystals of synthetic quartz containing amounts of OH in the range 700-6000 ppm of H/Si have been deformed plastically at 3-kb confining pressure, and the influence on their behavior of temperature, crystal orientation, OH content, and strain rate has been examined. Three stages can generally be distinguished in the stress-strain curve after...
Article
Full-text available
The petrography and structure of three small areas, the Nussbaum Riegel and the north and south sides of the Garwood Valley in the “Dry Valleys” region of Victoria Land, Antarctica, are described and discussed. The rocks are mostly pure or impure marbles plus lesser quantities of amphibolite, schist and quartz‐feldspar rocks, and mineral assemblage...
Article
The general theory of inhomogeneous finite strain is outlined. For any deformation it is possible to define two quantities, ckm and ckm, which are the deformation tensors. The principal axes of these tensors are the principal axes of strain at each point in the body and the proper numbers of these tensors are the values and reciprocals respectively...
Article
Transmission electron microscopy has been used for the direct observation of dislocations in naturally-deformed olivine. The dislocations are arranged in arrays forming low-angle sub-boundaries which have been identified with features observed in the optical microscope. Comparison of this dislocation substructure with that observed in olivine, and...
Article
Single crystals of experimentally deformed synthetic quartz showing optical deformation lamellae were examined by transmission electron microscopy. Dislocations are distributed fairly uniformly throughout the crystal. However, parallel to the trace of the deformation lamellae, which may be irrational, there are walls of tangled dislocations whose c...
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Full-text available
We examine the influence of the migration of chemical constituents, driven by gradients in normal stress, upon the evolution of fold geometry in anisotropic, linearly- viscous, multi-layered materials. The layering consists of an alternating sequence of high viscosity, chemically mobile rock and lower viscosity, chemically immobile rock. In a natur...
Article
ABSTRACT Many shear zones in the lithosphere,have,had very long periods of activity during Earth history commonly involving many,repeated,periods of rejuvenation. An example,is the closing and reopening,of the Atlantic along the same boundary. Another example is the Darling Fault in Western Australia , which has been reactivatedmany times in the pe...
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Full-text available
We have used simplified crustal scale architectures for the late Archean Yilgarn craton to present a range of numerical modeling scenarios investigating structural and thermal constraints on the potential distribution of late orogenic lode gold mineralization. Current conceptual models for gold mineralization the Yilgarn require precipitation over...
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Full-text available
We present a discussion of the processes involved in the operation of hydrothermal mineralizing systems with an emphasis on the mechanics of these systems. The term mechanics is used here to mean the science involved in understanding the behaviour of a fluid saturated porous solid subjected to a general stress state, whilst also subjected to gradie...
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Full-text available
We consider the influence of folds on the mineralization patters in hydrothermal systems within the upper crust of the Earth. This goal was achieved by the numerical modelling of the coupled problem between pore-fluid flow, thermal flow and mass flow as well as the related chemical reactions in folded hydrothermal systems. From the modern mineraliz...
Article
Traducción de: An outline of structural geology Incluye bibliografía e indice
Article
Zusammenfassung Eine Methode zur Rekonstruktion der ursprünglichen Form tektonisch deformierter Sediment-Strukturen wird dargelegt. Dabei werden keine Annahmen bezüglich des Spannungszustandes im Gestein gemacht. Beispiele sind angeführt, in denen ein rein tektonischer Ursprung der beobachteten Asymmetrie gewisser Sediment-Strukturen aufgezeigt wir...
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Full-text available
Three types of experiment have been carried out to investigate the influence of stress, strain and initial crystallographic orientation on the recrystallization of single crystals of quartz. These experiments are: (1) stress annealing experiments, in which the specimen is loaded to a high differential stress at a relatively low temperature and the...
Article
Layering of metamorphic origin which cuts recognizable bedding is described from slates, phyllites, and andalusite mica schists. The layering may be parallel to slaty cleavage or crenulation cleavage, or may be independent of any recognizable planar tectonic structure. In most examples, the development of metamorphic layering is associated with het...
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Full-text available
The paper reviews recent works on the Broken Hill ore body to see what data is available on the origin and history of the ore. A high grade metamorphism is recognizable (the Willyama Metamorphism) and this was followed by a number of retrograde metamorphic events. The characteristics of these events is described and this is followed by an analysis...
Article
In the high‐grade (granulite facies) metamorphic rocks at Broken Hill the foliation is deformed by two groups of folds. Group 1 folds have an axial‐plane schistosity and a sillimanite lineation parallel to their fold axes; the foliation has been transposed into the plane of the schistosity by these folds. Group 2 folds deform the schistosity and di...
Article
The microfabric of tectonites from the Wyangala Dam area, New South Wales, is characterized by the presence of linear fabric domains in which the quartz grains possess a similar orientation of [0001]. In folded rocks, there is a close relationship between the position of a certain domain and heterogeneities in the deformation. Thus, whether the fab...
Article
The sediments immediately adjacent to the Wyangala Batholith show direct evidence of two periods of folding. The first visible folds are tightly appressed structures which transpose the bedding to produce a new layering. The plunge of these folds is variable but there is no information to distinguish between superposition on an older generation of...
Article
The small area surrounding Narooma provides an example of a departure from the ideal geometry of superposed fold systems. Three systems of folds are recognized, the second set being by far the best developed. Axial planes of these folds lack a preferred orientation so that the fold style is polyclinal and B‐axes are variable. Evidence of extension...
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Full-text available
The latite intrusion near Port Kembla, New South Wales, is a flat-topped laccolith intruded into marine tuffaceous sediments of Permian age. Systematic study of internal structures revealed that movement in the direction of primary flow structures continued into post-consolidation and post-alteration stages. Contact relations and structures of incl...

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Project (1)
Archived project
To analyse the dynamics of chemical reactors in form of hydrothermal geological systems as nonlinear, non-equilibrium dynamical, open flow systems. The influx of heat, of chemical components in solution and momentum are implicitly contained and related over time series analysis from experimental data to deterministic regular and irregular (chaotic) dynamics.