Sketch of spreading segments separated by ridge-axis discontinuities in slow-spreading ocean crust. The crust at inside corners (IC) differs significantly from that at outside corners (OC) in that it is more elevated, thinner, and faulted into a blockier fabric. This asymmetry is thought to be caused by consistent dip of faults from inside corners to beneath outside corners, so that lower crust and upper mantle are commonly exhumed in the IC footwalls of the faults. Near a segment center on the front face of the diagram, hot, upwelling mantle decompresses and partially melts, supplying magma that is intruded and extruded to form the ocean crust[back]
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