The effect of stress on faulting and minor intrusions in the vicinity of a magma body
The stress field in the vicinity of a body of fluid of simple geometry contained within a non-homogeneously stressed solid has been calculated and the result applied to the case of a magma body within a region of the crust subject to triaxial stresses. The types of faulting and minor intrusion which result are described.The theory indicates that the regional stresses in the crust together with the magma pressure control the type of faulting, the form of the minor intrusions and the occurrence of eruptions from the magma body.The stress conditions favouring caldera formation, the intrusion of radial dykes, dyke swarms and cone sheets are described.