A zone of tectonic enlargement, and substantial, and strongly asymmetric, sedimentation. A back-arc basin forms when an island arc is split along the line of its magmatic axis, forming a remnant arc, which then glides away. Well-developed back-arc basins widen by back-arc spreading, which is thought to resemble normal oceanic crust formation, but in conjunction with a subducting plate. See Ohara (2006) Island Arc 15, 1 for a general view of the mantle process beneath a back-arc basin spreading ridge.
Subjects: Earth Sciences and Geography.