Emplacement and Segment Geometry of Large, High-Viscosity Magmatic Sheets

Understanding magma transport in sheet intrusions is crucial to interpreting volcanic unrest. Studies of dyke emplacement and geometry focus predominantly on low-viscosity, mafic dykes. Here, we present an in-depth study two high-viscosity dykes (106 Pa·s) the Chachahuén volcano, Argentina, Great Dyke Sosa Dyke. To quantify geometries, flow indicators, viscosity, combine photogrammetry, microstructural analysis, igneous petrology, Fourier-Transform-Infrared-Spectroscopy, Anisotropy Magnetic Susceptibility (AMS). Our results show that consist 3 8 mappable segments up 2 km long. Segments often end a bifurcation, segment tips are oval, but elliptical occur outermost Furthermore, variations host rocks have no observable impact geometry. AMS fabrics other indicators lateral contrast vertical suggested by geometries. A comparison with geometries low-viscosity shows our follow same geometrical trend. In fact, data compilation supports tip reflect different stages emplacement, questioning current usage for final as proxies mechanism.