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Such terranes were dubbed "accreted terranes" by geologists. Geologist J. N. Carney writes: It was soon determined that these exotic crustal slices had in fact originated as "suspect terranes" in regions at some considerable remove, frequently thousands of kilometers, from the orogenic belt where they had eventually
An older assumption that backstops of accretionary wedges dip back toward the arc, and that accreted material is emplaced below such backstops, is contradicted by observations from many active forearcs that indicate (1) backthrusting is common, (2) forearc basins are nearly ubiquitous associates of accretionary wedges, and (3) forearc basement ...
Most continents are composed of multiple accreted "terranes", pieces of low-density continental crust with different origins. For example, North America is made up of multiple accreted terranes that collided with the Laurentian proto-continent, such as the Proterozoic Yavapai, Mazatzal, and Grenville Province Terranes. [5]
Geologic map depicting the Smartville Complex (in brown) and other accreted terranes in California. [1]The Smartville Block, also called the Smartville Ophiolite, Smartville Complex, or Smartville Intrusive Complex, is a geologic terrane formed in the ocean from a volcanic island arc that was accreted onto the North American Plate during the late Jurassic (~160–150 million years ago).
The latter stages of orogenesis, in contrast, saw multiple oceanic arc terranes accreted onto the western margin of North America in a "Cordilleran type" accretionary orogen. [2] Deformation related to the accretion of these volcanic arc terranes is mostly limited to the western regions of the resulting mountain ranges ( Klamath Mountain range ...
[1] [2] The region's geologic border to the north is composed of the Rio de la Plata craton and several accreted terranes comprising the La Pampa province. [3] The underlying basement rocks of the Patagonian region can be subdivided into two large massifs: the North Patagonian Massif and the Deseado Massif.
These fragments from elsewhere are called terranes (sometimes, "exotic" terranes). During the subduction of the Farallon plate, it accreted these island arcs and terranes to the North American plate. Much of western North America is composed of these accreted terranes.
The Acadian orogeny resulted from oblique convergence or major transcurrent movement along a large strike-slip fault which represents the zone of convergence between Laurussia/Laurentia and Avalon terranes. [4] One or more of the Avalonian terranes accreted with the eastern margin of Laurentia, most likely beginning in the late Early Devonian. [9]