Making an accretionary prism Flashcards
What is an accretionary prism known as?
Accretionary prism is also known as the subduction complex (Barbados ridge
What forms a trench?
a clear subducting plate which forms a trench
What happens first?
Subduction: The convergence of tectonic plates results in one plate, typically an oceanic plate, being forced beneath the other plate, usually a continental plate. This process is known as subduction. The subducting plate descends into the mantle beneath the overriding plate.
What happens second?
Sediment Scrape-off: As the oceanic plate descends into the mantle, it encounters resistance from the overriding continental plate. This resistance causes the subducting plate to deform and undergo intense pressure. The leading edge of the subducting plate starts to crumple and break apart, causing the sediment and rock material that had accumulated on the subducting plate to be scraped off.
What happens third?
Accretion: The scraped-off sediment and rock material accumulate at the base of the overriding continental plate, forming an accretionary prism or wedge. The sediments are typically fine-grained and can include mud, sand, and various types of rocks. Over time, the accretionary wedge grows in thickness as more material is accreted.
What happens fourth?
Thrusting and Folding: The intense pressure and deformation associated with subduction can cause the sediments in the accretionary wedge to undergo folding and faulting. Thrust faults develop, with older sediment layers being thrust over younger layers. This folding and faulting contribute to the structural complexity of the wedge.
What happens fifth?
Deformation and Metamorphism: The sediments in the accretionary wedge experience increasing pressure and temperature as they are buried deeper within the Earth. This leads to metamorphism, a process where the minerals and textures of the sedimentary rocks are altered. The sediments may undergo transformation into metamorphic rocks such as schist or slate.
