Crustal accretion at mid-ocean ridges and backarc spreading centers: Insights from the Mid-Atlantic Ridge, the Bransfield Basin and the North Fiji Basin

Abstract

Mid-Ocean Ridges are a natural laboratory for the study of magmatic and tectonic processes and their interactions. Owing to their relatively simple structure and geodynamic history, they have been studied by highly active projects, such as RIDGE (USA), followed by the international initiative InterRidge, which have yielded enormous advances during the last two decades. By these ridge-oriented initiatives, a large portion of the global ridge system has been explored, mapped and sampled. These data have constrained models of melt production and dynamics of the mantle, formation of the lithosphere, magmatic accretion of the crust, tectonic deformation, and volcanic processes at shallow levels, as well as their interactions. Geophysical observations (bathymetry, acoustic backscatter, and gravity) from several sites along mid-ocean ridges (Mid-Atlantic Ridge) and two back-arc basins (Bransfield and North Fiji) summarized here provide constraints on the surface expression of ridge tectonism, volcanism, and the density structure of the oceanic lithosphere in depth, and their bearing on the accretionary processes at ridges.