A self-consistent model of melting, magma migration and buoyancy- driven circulation beneath mid-ocean ridges

Abstract

Numerical modeling and analysis are used to investigate the processes leading to the eruption of mantle-derived magma at mid-ocean ridges. Our model includes the following effects: melting due to decompression, magma migration by percolation, and circulation of the mantle driven by both the oceanic plates and the distribution of buoyancy beneath the ridge. The distribution of buoyancy is due to both the low density of the liquid and the difference in the density of the residual solids relative to unmelted mantle material. Our results provide a simple explanation for the narrowness of the zone of crustal formation at mid-ocean ridges. The model also predicts a transition from steady state to episodic crustal formation as the spreading velocity is reduced, perhaps giving rise to along-axis variations in the character of seafloor spreading. -from Authors