6 research outputs found
Inelastic deformation during sill and laccolith emplacement: Insights from an analytic elastoplastic model
Numerous geological observations evidence that inelastic deformation occurs
during sills and laccoliths emplacement. However, most models of sill and
laccolith emplacement neglect inelastic processes by assuming purely elastic
deformation of the host rock. This assumption has never been tested, so that
the role of inelastic deformation on the growth dynamics of magma intrusions
remains poorly understood. In this paper, we introduce the first analytical
model of shallow sill and laccolith emplacement that accounts for
elasto-plastic deformation of the host rock. It considers the intrusion's
overburden as a thin elastic bending plate attached to an
elastic-perfectly-plastic foundation. We find that, for geologically realistic
values of the model parameters, the horizontal extent of the plastic zone lp is
much smaller than the radius of the intrusion a. By modeling the quasi-static
growth of a sill, we find that the ratio lp/a decreases during propagation, as
1/ \sqrt a 4 P , with P the magma overpressure. The model
also shows that the extent of the plastic zone decreases with the intrusion's
depth, while it increases if the host rock is weaker. Comparison between our
elasto-plastic model and existing purely elastic models shows that plasticity
can have a significant effect on intrusion propagation dynamics, with e.g. up
to a doubling of the overpressure necessary for the sill to grow. Our results
suggest that plasticity effects might be small for large sills, but conversely
that they might be substantial for early sill propagation.
Harmonic oscillator in a background magnetic field in noncommutative quantum phase-space
We solve explicitly the two-dimensional harmonic oscillator and the harmonic
oscillator in a background magnetic field in noncommutative phase-space without
making use of any type of representation. A key observation that we make is
that for a specific choice of the noncommutative parameters, the time reversal
symmetry of the systems get restored since the energy spectrum becomes
degenerate. This is in contrast to the noncommutative configuration space where
the time reversal symmetry of the harmonic oscillator is always broken.Comment: 7 pages Late
Formulation, Interpretation and Application of non-Commutative Quantum Mechanics
In analogy with conventional quantum mechanics, non-commutative quantum
mechanics is formulated as a quantum system on the Hilbert space of
Hilbert-Schmidt operators acting on non-commutative configuration space. It is
argued that the standard quantum mechanical interpretation based on Positive
Operator Valued Measures, provides a sufficient framework for the consistent
interpretation of this quantum system. The implications of this formalism for
rotational and time reversal symmetry are discussed. The formalism is applied
to the free particle and harmonic oscillator in two dimensions and the physical
signatures of non commutativity are identified.Comment: 11 page
Supersymmetry breaking in noncommutative quantum mechanics
Supersymmetric quantum mechanics is formulated on a two dimensional
noncommutative plane and applied to the supersymmetric harmonic oscillator. We
find that the ordinary commutative supersymmetry is partially broken and only
half of the number of supercharges are conserved. It is argued that this
breaking is closely related to the breaking of time reversal symmetry arising
from noncommutativity
Drainage fracture networks in elastic solids with internal fluid generation
Experiments in which CO2 gas was generated by the yeast fermentation of sugar in an elastic layer of gelatine gel confined between two glass plates are described and analyzed theoretically. The CO2 gas pressure causes the gel layer to fracture. The gas produced is drained on short length scales by diffusion and on long length scales by flow in a fracture network, which has topological properties that are intermediate between river networks and hierarchical-fracture networks. A simple model for the experimental system with two parameters that characterize the disorder and the intermediate (river-fracture) topology of the network was developed and the results of the model were compared with the experimental results