Dynamics of dikes versus cone sheets in volcanic systems
Résumé
Swarms of hundreds to thousands of igneous sheet intrusions represent the main magma pathways through the Earth’s brittle crust. Igneous sheet intrusions of various shapes, such as dikes and cone sheets, coexist as parts of complex volcanic plumbing systems likely fed by common sources. How they form is fundamental regarding volcanic hazards, but yet no dynamic model simulates and predicts satisfactorily their diversity. Here we present scaled laboratory experiments that reproduced dike and cone sheet intrusion geometries under controlled conditions (Galland et al., 2014). The model rock is fine-grained, cohesive Coulomb crystalline silica flour. The model magma is a molten vegetable oil injected at constant flow rate. After the experiments, the oil solidifies and the intrusion is excavated to observe its shape.