Deep plate serpentinization triggers skinning of subducting slabs

Tectonic slicing of subducting oceanic crust along plate interfaces: Numerical modeling

“…In nature, blueschists and eclogites of oceanic crust are exhumed along different compressional settings related to subduction all over the world [ Agard et al ., ; Maruyama et al ., ]. Such crustal slivers can be detached and underplated during arc‐continent collision [ Boutelier et al ., ], orogenic collision [ Yamato et al ., ], but also during ongoing oceanic subduction, as indicated be seismic reflectors [ Vogt and Gerya , , and references therein]. The timing of exhumation of these metamorphic rocks can be early, intermediate or late, with respect to the subduction cycle [ Agard et al ., ].…”

“…Of the above mentioned factors, only little work has been done on investigating the role of a serpentinized lithospheric slab mantle in decoupling the oceanic crust from the descending slab and detaching oceanic slivers in a physically consistent framework [Vogt and Gerya, 2014], thus justifying a numerical modelling study. Vogt and Gerya [2014] have shown that increased thickness and increased serpentine content below the oceanic crust enhance slicing but pointed out as well the importance of plate coupling during process. However, the role of slab mantle serpentinites appears to be very important because many observations such as ocean drilling suggest that seafloor peridotites can be extensively serpentinized (50-100%) [Fruh-Green et al, 1996] as a result of (i) sea water hydrothermal alteration [Janecky and Seyfried, 1986;Martin and Fyfe, 1970] along large-scale detachment faults [McCaig et al, 2007;Tucholke et al, 1998] and transform faults off-axis mid-ocean ridges [Cann et al, 1997;Kelley et al, 2001] or in increased fluid-flux areas at midplate regions [Hutnak et al, 2008], and (ii) infiltration of seawater into deep bending normal faults at the outer rise prior to subduction [Ivandic et al, 2010;Ranero et al, 2003].…”

Obduction triggered by regional heating during plate reorganization

“…Establishing the processes responsible for the emplacement of ophiolites, dense sections of oceanic lithosphere atop lighter continental plates, is a long‐standing unsolved scientific question (Coleman, , ; Dewey, ; Moores, ; Vaughan and Scarrow, ). Modelling obduction has proven difficult, as the processes involved are numerous, and include changes in plate kinematics (Agard et al ., ), the subduction dynamics of the underthusted lithosphere (Yamato et al ., ; Duretz et al ., ), weakening of the oceanic plate rheology due to serpentinization (Vogt and Gerya, ), gravity‐driven propagation of the ophiolite over its foreland basin following flexure of underthrusted lithosphere (Lagabrielle et al ., ), negative buoyancy (Cloos, ) of the obducted oceanic crust and overall mantle dynamics (Vaughan and Scarrow, ).…”

The Hydrocarbon Potential of Paleo- And Modern Suprasubduction Zones: Tectonic, Geodynamic, Mineralogical-Geochemical, and Biochemical Aspects

“…Эти процессы повышали пластичность мантийных масс и способствовали их выведению в кору: пластичные оливин-антигоритовые сланцы служили «рельсами» для выведения мантийных глубинных масс в верхние горизонты коры. В численной модели расслоения океанической коры в надсубдукционной области ведущая роль отводится ослабленному серпентинитовому горизонту [60]. Рассматриваемый нами случай принципиально отличается от этой модели тем, что процесс детачмента на границе кора-мантия происходит не в субдуцируемом слэбе, а в мантийном клине над зоной субдукции.…”