Mid-ocean ridge magmatism and volcanism

Abstract

The global mid-ocean ridge system is a vast, complicated array of volcanoes, the great majority of which remain unvisited and sparsely sampled. Detailed studies at a few dozen sites reveal patterns of volcanic style, magmatic processes, and erupted compositions that generally reflect variations in spreading rate, magma supply, mantle composition, and proximity to ridge discontinuities and hotspots. Such studies also reveal the range of site-specific geological conditions that affect MORB composition and mid-ocean ridge volcanism. These effects are being studied in ever more locales at ever higher resolution to understand the spatial and temporal scales of ocean ridge magmatic processes, revealing how mid-ocean ridge volcanoes operate and how they sample the underlying mantle. Combined petrological, geochemical, geophysical, and geological data about mid-ocean ridges indicate that inferred mantle compositions are significantly modified in range, magnitude, and length scale at mid-ocean ridges by preeruptive magmatic processes such as magma residence and transport through the upper mantle and lower crust. Submarine eruptions construct new ocean crust and are a primary agent for the transfer of heat, chemicals, and microbes from the Earth’s mantle or crust into the overlying ocean. Studying these eruptions is therefore important as well for a complete understanding of the chemistry and biology of the deep sea.