How Do Tectonic Stresses and Lithospheric Heterogeneity Control Large-Scale Volcanism?
The lithospheric structure is an important factor controlling the distribution and chemical composition of the large-scale volcanism. The primary magmas related to the hotspot events are often emplaced into the crust in the form of dolerite dikes radiating from a volcanic centre. Since the emplacement is geologically fast, the general pattern of the dike swarms may be used to obtain the orientation of horizontal tectonic stresses at the time of emplacement. However, the robustness of this approach was questioned in the view of possible complex modes of magma emplacement and lithospheric heterogeneity.
The heterogeneities can activate certain dike propagation paths but do not affect the trajectory. The effect of intrinsic elastic anisotropy versus tectonic stress (stress anisotropy) cannot be separated from the geometry of dikes along and, thus, requires additional constraints (such as seismic anisotropy data.
The aim of the project is to model the dike propagation using methods of continuum mechanics assuming that the dikes form as a result of shear or tensile fractures. The effects of heterogeneities, elastic anisotropy and stress anisotropy will be studied.