Geophysical constraints on mantle flow and melt generation beneath mid-ocean ridges

The title "Geophysical constraints on mantle flow and melt generation beneath mid-ocean ridges" can be interpreted in two ways: either as observational constraints on models, or as the constraints that physical properties and boundary conditions place on the flow itself. In this review, I concentrate primarily on the observational constraints, but to fully understand the problem of production and delivery of the magma that forms the oceanic crust we must understand the physics and chemistry of the process. All the observational tools we possess lack the resolution to define the details of the structure on a fine enough scale to expect that we can ever simply map the pattern of mantle flow or melt production. We must rely on theoretical models to provide the detail, testing the predictions of the models against observational and experimental constraints.