page_title: Fracture zone
section_title: Structure and formation
hierarchical_section_title: Fracture zone / Structure and formation
caption_attribution_description: Fracture Zone - bstern3
context_page_description: A fracture zone is a linear oceanic feature—often hundreds, even thousands of kilometers long—resulting from the action of offset mid-ocean ridge axis segments. They are a consequence of plate tectonics. Lithospheric plates on either side of an active transform fault move in opposite directions; here, strike-slip activity occurs. Fracture zones extend past the transform faults, away from the ridge axis; seismically inactive, they display evidence of past transform fault activity, primarily in the different ages of the crust on opposite sides of the zone.
  In actual usage, many transform faults aligned with fracture zones are often loosely referred to as "fracture zones" although technically, they are not.
context_section_description: Mid-ocean ridges are divergent plate boundaries. As the plates on either side of an offset mid-ocean ridge move, a transform fault forms at the offset between the two ridges.
  Fracture zones and the transform faults that form them are separate but related features. Transform faults are plate boundaries, meaning that on either side of the fault is a different plate. In contrast, outside of the ridge-ridge transform fault, the crust on both sides belongs to the same plate, and there is no relative motion along the junction.  The fracture zone is thus the junction between oceanic crustal regions of different ages.  Because younger crust is generally higher due to increased thermal buoyancy, the fracture zone is characterized by an offset in elevation with an intervening canyon that may be topographically distinct for hundreds or thousands of kilometers on the sea floor.
caption: Oceanic crust age differences and ridge-ridge transform faulting associated with offset mid-ocean ridge segments lead to the formation of fracture zones.
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