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The mechanism of arc subduction is well understood to be the location where new continental crust is formed and is presumably also the site of subcontinental mantle genesis. Firstly, hydrated oceanic crust slabs begin subducting which releases fluids (subduction zone metamorphism) to the mantle wedge above. Continued subduction of the slab ...
Cratons of South America and Africa during the Triassic Period when the two continents were joined as part of the Pangea supercontinent. A craton (/ ˈ k r eɪ t ɒ n / KRAYT-on, / ˈ k r æ t ɒ n / KRAT-on, or / ˈ k r eɪ t ən / KRAY-tən; [1] [2] [3] from Ancient Greek: κράτος kratos "strength") is an old and stable part of the continental lithosphere, which consists of Earth's two ...
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 a geological process in which the oceanic lithosphere and some continental lithosphere is recycled into the Earth's mantle at the convergent boundaries between tectonic plates. Where one tectonic plate converges with a second plate, the heavier plate dives beneath the other and sinks into the mantle.
Crustal growth rates can be used to calculate estimates for the age of the continental crust. This can be done through analysis of igneous rocks with the same isotopic composition as initial mantle rock. These igneous rocks are dated and assumed to be direct evidence of new continental crust formation. [22]
It is suggested that the regime of subduction under the Laurentian margin (currently in Texas, north of the accreted Mexican terrane) ended around 1230 Ma, and that subduction polarity reversed to bring the colliding continent north, since the Llano Uplift, which records the history of the Grenville in Texas, bears no evidence of arc magmatism ...
The earliest effort to relate plate tectonics specifically to the Antler orogeny was briefly outlined by E.M. Moores: A collision of this continental margin with a subduction zone dipping away from it in late Devonian-early Mississippian time ... resulted in deformation of the pre-existing continental marginal rocks in the Antler Orogeny. [14]
The western edge of the North American continent was later pushed against the oceanic plate under the adjacent ocean. An area of great compression called a subduction zone was formed in the early-to-mid Mesozoic, which replaced the quiet, sea-covered continental margin with erupting volcanoes and uplifting mountains. [13]