The oceanic lithosphere forms at the summit of ocean ridges during seafloor spreading. Still, the formation of ocean basins is complex, influenced by smaller-scale convection, stagnated pieces of the lithosphere, and tectonic motion from nearby plates. These factors can produce a solid, outer layer of Earth with different structures at different depths.
Click here for original story, Small-scale convection shuffles the oceanic lithosphere, finds study
Source: Phys.org