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The Mesoarchean era is thought to be the birthplace of modern-style plate subduction, based on geologic evidence from the Pilbara Craton in western Australia. [ 3 ] [ 4 ] A convergent margin with a modern-style oceanic arc existed at the boundary between West and East Pilbara approximately 3.12 Ga.
retreating subduction: caused by weak coupling between the lower and upper plate which leads to the opening of a back arc basin and the subduction zone being moved by slab rollback. stable subduction: caused by intermediate coupling between the lower and upper plate. The subduction zone generally stays in the same place and the subduction plate ...
The earliest record of subhorizontal subduction of the Farallon slab is the extinguishing of magmatism in the Sierra Nevada batholith of California roughly 85 Ma. [7] As the Farallon Plate subducted below the California continental margin an accretionary wedge was formed in the trench, which yielded unique rock types as a result of regional ...
Subduction is the density-driven process by which one tectonic plate moves under another and sinks into the mantle at a convergent boundary.Gravitational pull from dense slabs provides approximately 90% of the driving force for plate tectonics, [2] and consequently subduction is crucial in changing the Earth's layout, guiding its thermal evolution [3] and building its compositional structure. [1]
Evidence for this increased subduction activity comes from the abundance of old granites originating mostly after 2.6 Ga. [14] The occurrence of eclogite (a type of metamorphic rock created by high pressure, > 1 GPa), is explained using a model that incorporates subduction. The lack of eclogites that date to the Archean Eon suggests that ...
[18] [19] The bottom of the trench marks the boundary between the subducting and overriding plates, known as the basal plate boundary shear [20] or the subduction décollement. [2] The depth of the trench depends on the starting depth of the oceanic lithosphere as it begins its plunge into the trench, the angle at which the slab plunges, and ...
The figure is a schematic diagram depicting a subduction zone. The subduction slab on the right enters the mantle with a varying temperature gradient while importing water in a downward motion. A model of the subducting Farallon slab under North America. In geology, the slab is a significant constituent of subduction zones. [1]
Instead, a model of "flake tectonics" has been proposed for this era of geologic time. According to this model, instead of normal subduction of oceanic plates, extensively silicified upper oceanic crust delaminated from lower oceanic crust and was deposited in a manner similar to ophiolites from the later Proterozoic and Phanerozoic eons. [10]