The region where oceanic plates sink down into the asthenosphere is called a subduction zone . Oceanic/Oceanic Collisions When two oceanic plates collide, one of the oceanic plates slides under the other, much as in a continental/oceanic collision.
What is it called when regions of Earth’s surface sink down?
A region where this process occurs is known as a subduction zone , and its surface expression is known as an arc-trench complex. The process of subduction has created most of the Earth’s continental crust. ... Once initiated, stable subduction is driven mostly by the negative buoyancy of the dense subducting lithosphere.
Why does the oceanic plate sink into the asthenosphere?
The oceanic lithosphere is normally floating on the asthenosphere. When the plate is subjected to compression, it subducts beneath the contacted continental plate . The plate tends to sink deeply down to 660 km depth.
Where do the plates sink down?
Old parts of a plate are likely to sink down into the mantle at subduction zones because they are colder and thicker than the warm mantle material underneath them. This is called slab pull.
Where is an oceanic plate destroyed at?
The trenches are sites where old oceanic lithosphere is being destroyed, or subducted, beneath younger lithosphere. For this reason, destructive boundaries are often referred to by their alternative name of subduction zones.
Are the continents sinking?
The continents, “floating” on the earth’s denser interior, have sunk as much as two miles below their “proper” height , according to a report in the February issue of Geophysical Research Letters. ... It has long been assumed that the continents float on the underlying rock, just as an iceberg floats in water.
What happens when two oceanic plates collide?
When an ocean plate collides with another ocean plate or with a plate carrying continents, one plate will bend and slide under the other . This process is called subduction. A deep ocean trench forms at this subduction boundary.
What is an example of oceanic oceanic convergence?
Examples of ocean-ocean convergent zones are subduction of the Pacific Plate south of Alaska (creating the Aleutian Islands) and under the Philippine Plate, where it creates the Marianas Trench, the deepest part of the ocean.
What is in the asthenosphere?
- It is a layer of solid rock that has so much pressure and heat the rocks can flow like a liquid.
- The rocks are also less dense than the rocks in the lithosphere.
- It is believed to be much hotter and more fluid than the lithospher.
Which is the first step in the seafloor spreading process?
1. A long crack in the oceanic crust forms at a mid ocean ridge . 2. Molten material rises and erupts along the ridge.
What are the 3 causes of plate movement?
Mantle dynamics, gravity, and Earth’s rotation taken altogether causes the plate movements. However, convectional currents are the general thought for the motion.
What drives the plate to move?
The heat from radioactive processes within the planet’s interior causes the plates to move, sometimes toward and sometimes away from each other. This movement is called plate motion, or tectonic shift.
Do plates shrink and grow in area?
Each of earth’s plates contain only one of the three types of plate boundaries. Plates shrink and grow in area . ... Tyoe of plate boundary that occurs when a plate of oceanic lithosphere plunges beneath an overriding plate of contniental crust.
What are the 4 types of plate tectonics?
There are four types of boundaries between tectonic plates that are defined by the movement of the plates: divergent and convergent boundaries, transform fault boundaries , and plate boundary zones.
How did you classify the three types of plate boundaries What was your basis?
The movement of the plates creates three types of tectonic boundaries: convergent, where plates move into one another; divergent, where plates move apart ; and transform, where plates move sideways in relation to each other.
What is the difference between oceanic plates and continental plates?
Oceanic plates are much thinner than the continental plates . ... At the convergent boundaries the continental plates are pushed upward and gain thickness. The rocks and geological layers are much older on continental plates than in the oceanic plates. The Continental plates are much less dense than the Oceanic plates.
