Stress field

About: Stress field is a research topic. Over the lifetime, 11926 publications have been published within this topic receiving 226417 citations.

Accelerated hydration of the Earth's deep crust induced by stress perturbations

Abstract: The metamorphic cycle associated with the formation of mountain belts produces a lower crust containing little or no free fluid1,2. The introduction of external fluids to dry and impermeable volumes of the Earth's crust is thus a prerequisite for the retrogressive metamorphism later observed in such regimes. Such metamorphism can cause significant changes in the crust's physical properties, including its density, rheology and elastic properties3,4. On a large scale, the introduction of fluids requires the presence of high-permeability channels, such as faults or fractures, which are the result of external tectonic stresses. But extensive interaction between externally derived fluids and the fractured rock requires efficient mass transport away from the initial fractures into the rock itself, and this transport often occurs over distances much longer than expected from grain-boundary diffusion. Here we present both field observations and a simple network model that demonstrate how the transport of fluids into initially dry rock can be accelerated by perturbations in the local stress field caused by reactions with fluids. We also show that the morphology of reaction fronts separating ‘dry’ from ‘wet’ rocks depends on the anisotropy of the external stress field.

Three-Dimensional Stress Fields of Elastic Interface Cracks

Abstract: Various aspects of stress fields near an interface crack in three-dimensional bimaterial plates are investigated. Due to the nature of the resulting deformation field, three-dimensional effects are more critical in a bimaterial plate than in a homogeneous plate. In the close vicinity of the crack front, the stress field is characterized by the asymptotic bimaterial K -field, and its domain size is a very small fraction of a plate thickness. Unlike a homogeneous case, the asymptotic field always consists all three modes of fracture, and an interface crack must propagate under mixed-mode conditions. Furthermore, computational results have shown that the two phase angles representing the relative magnitudes of the three modes strongly depend on the bimaterial properties. It has been also observed that a significant antiplane (Mode III) deformation exists along the crack front, especially near the free surface. Since experimental investigations have shown that critical energy release rate G c is highly dependent on the phase angles, accurate prediction of the interface fracture behavior requires not only the G distribution but also the variations of phase angles along the crack front.

Indochina Peninsula and the collision of India and Eurasia

Abstract: The collision of India with Asia results in a rapidly changing stress pattern around both Himalayan syntaxes. The maximum compressive stress, which is north- south north of the indenter, fans radially through nearly 180° around the syntaxes to accommodate the necessary strike-slip motion on the edges of the indenter. Thus, the whole Indochina Peninsula was swept by the migrating stress and associated strain pattern as the eastern syntaxis moved to the north. As a result, the maximum horizontal component of the stress field is predicted to have been first oriented east-west, then north-south. We propose that this changing stress field controlled the opening of the sedimentary basins and of the South China Sea as well as the direction of motion of the major strike-slip faults.