Table of Contents
What is accretion in tectonic plates?
Accretion, in geology, is a process by which material is added to a tectonic plate at a subduction zone, frequently on the edge of existing continental landmasses. The added material may be sediment, volcanic arcs, seamounts, oceanic crust or other igneous features.
What is the difference between terrain and terrane?
What is the difference between terrane and terrain? “Terrane” describes a crustal fragment consisting of a distinct and recognizable series of rock formations that has been transported by plate tectonic processes, whereas “terrain” describes the shape of the surface topography.
What is continental accretion and how does it happen?
Accretion is a process by which material is added to a tectonic plate or a landmass. This material may be sediment, volcanic arcs, seamounts or other igneous features, or blocks or pieces of continental crust split from other continental plates.
How do exotic terranes become part of a continent?
Plate tectonics explains how terranes can be moved across an ocean and added to a continent. Because terranes come from a distant location they are often referred to as exotic terranes. Part of the continent can then drift away on a moving plate to become an accreted terrane on another continent.
What is a terrane in geology?
A terrane is a fault-bounded package of rock sequence of regional extent with distinctive geologic history (Coney, Jones, & Monger, 1980). It is well recognized that the present spatial juxtaposition of terranes in any orogen does not necessarily reflect their relative position prior to their assembly.
Where do accreted terranes form?
Continents Grow Outward by Terrane Accretion In the digram below, an oceanic island or continental fragment (incoming terrane) approaches a subduction zone, where it will eventually attach (accrete) to the edge of the continent.
What is continental Assimilation Hypothesis?
The “continental assimilation” hypothesis stated that oceans accumulated the denser elements, then subsided to form basins. Fossils and lithologies on several continents now separated by wide oceans show striking similarities.
What is terranes geography?
In geology, a terrane (in full, a tectonostratigraphic terrane) is a crust fragment formed on a tectonic plate (or broken off from it) and accreted or “sutured” to crust lying on another plate. …
Where are terranes found?
Unmetamorphosed sedimentary and volcanic accreted terrane rocks are widespread across the western part of the Cordillera with metamorphosed rocks present primarily in the northern California Coast Ranges, the northern Sierra Nevada, the Blue Mountain region of Oregon, the Klamath Mountains, and the North Cascades.
What are examples of accretion?
An example of an accretion is the garage someone may build on his home. (geology) The gradual extension of land by natural forces, as in the addition of sand to a beach by ocean currents, or the extension of a floodplain through the deposition of sediments by repeated flooding.
What are accreting terranes and how are they formed?
Typically, accreting terranes are portions of continental crust which have rifted off another continental mass and been transported surrounded by oceanic crust, or they are old island arcs formed at some distant subduction zone.
A terrane in geology, in full a tectonostratigraphic terrane, is a fragment of crustal material formed on, or broken off from, one tectonic plate and accreted or ” sutured ” to crust lying on another plate.
What are the characteristics of accreted terrain?
Accreted terrain when young, is very rugged due to the force that pushed the rock together. The terrain will be folded in some places where deformation was deep. Thrust faulting will be present at the surface where the rock was brittle.
Is terrane accretion possible at convergent plate boundaries?
Terrane accretion is most common at convergent plate boundaries, but it may be possible for a terrane to be brought from an exotic location along a transform plate boundary. It is also possible for a new divergent plate boundaryto develop that rifts a continent apart.