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A model of the subducting Farallon slab under North America. In geology, the slab is a significant constituent of subduction zones. [1] Subduction slabs drive plate tectonics by pulling along the lithosphere to which they attach in a process known as slab pull and by inducing currents in the mantle via slab suction. [2]
Subducting slabs are composed of basaltic crust topped with pelagic sediments; [61] however, the pelagic sediments may be accreted onto the forearc-hanging wall and not subducted. [62] Most metamorphic phase transitions that occur within the subducting slab are prompted by the dehydration of hydrous mineral phases.
A slab refers to the subducting lower plate. A broader definition of flat slab subduction includes any shallowly dipping lower plate, as in western Mexico. Flat slab subduction is associated with the pinching out of the asthenosphere, an inland migration of arc magmatism (magmatic sweep), and an eventual cessation of arc magmatism. [2]
Subducting slabs are composed of basaltic crust topped with pelagic sediments; [9] however, the pelagic sediments may be accreted onto the forearc-hanging wall and not subducted. [10] Most metamorphic phase transitions that occur within the subducting slab are prompted by the dehydration of hydrous mineral phases.
The direction of the subduction system changes since the break-off of slab creates the space, which is the major parameter of this model. [4] The evolution diagram showing how the subduction reversal initiated by a break-off slab at subducting plate: Brown colour is the less dense continental crusts; White colour is the oceanic crust; 1. Two ...
Slab suction is weaker than slab pull, which is the strongest of the driving forces. When measuring the forces of these two mechanisms, slab pull in subducting plate boundaries for upper mantle slabs is 1.9 × 10^21 N. [clarification needed] In comparison slab suction in the upper and lower mantle totaled 1.6 × 10^21 N. [3]
The subducting slabs carry volatile compounds and water into the mantle, as well as crustal material with an isotopic signature different from that of primitive mantle. Identification of this crustal signature in mantle-derived rocks (such as mid-ocean ridge basalts or kimberlites) is proof of crustal recycling.
Slab (geology), that portion of a tectonic plate that is subducting Slab pull force, the tectonic plate force due to subduction; Slab suction, one of the major plate tectonic driving forces; Slab window, a gap that forms in a subducted oceanic plate; Slab (fossil) and counter slab, the two counterparts of a fossil impression