Mechanics and Thermodynamics of Crustal Dike Propagation

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Two-third's of the Earth's crust is formed along mid-ocean ridges, where tectonic plates spread apart and molten basalt (magma) from the underlying mantle rises to fill the "gap" and freezes. By analogy with volcanic rift zones in Iceland and Hawaii, most shallow magma transport along ridges lacking a continuous magma chamber occurs in vertical cracks (dikes), that are typically a few kilometers tall and a meter or so wide, and that can propagate laterally for several tens of kilometers. Through a combination of numerical models and laboratory experiments, we will study the mechanical and thermal behavior of laterally-propagating dikes along mid-ocean ridges. We will focus on two aspects that are not addressed by existing models of this process: The role of the topographic slope in driving magma flow (the magma essentially runs "downhill"), and the role of heat flow in limiting the distance that dikes propagate. The goal is to determine the role of lateral dike propagation in contributing to the structure and topography of crust produced at slow-spreading mid-ocean ridges.