Fig. 6: The evolutionary history of the detachment faulting system with hydrothermal activity based on profiles L2 and L3.

Only upper crustal section is shown with corresponding spreading rate along profiles and projected polarity zones. a Profile L2 evolution shown from 1.48 Myr bp to present and b Profile L3 evolution shown from 0.74 Myr bp to present. Also shown are the breakaway B1 and termination T1 of OCC1 and the breakaway B2 and termination T2 of OCC2. Red lines represent the OCC slip surfaces, other lines are accretionary terrain, and gray area represents the stranded block on OCC2. LC refers to lower crust exhumed by OCC1 and OCC2 and presumed to be less magnetic than the upper crustal extrusive section. Slip is assumed to be continuous along the OCC fault surfaces when they are formed until they terminate (i.e. no stop and start behavior). OCCs are assumed to nucleate off-axis approx. 3–6 km from the axis of spreading (NVZ). Topography is only approximate and may not reflect past topographic nature.