What Happens To Old Oceanic Crust As New Molten Material Rises From The Mantle?

What is the oceanic crust made of?

Oceanic crust is generally composed of dark-colored rocks called basalt and gabbro.

It is thinner and denser than continental crust, which is made of light-colored rocks called andesite and granite.

The low density of continental crust causes it to “float” high atop the viscous mantle, forming dry land..

What happens to old oceanic crust as new oceanic crust forms?

At subduction zones, the edge of the denser plate subducts, or slides, beneath the less-dense one. The denser lithospheric material then melts back into the Earth’s mantle. Seafloor spreading creates new crust. Subduction destroys old crust.

What is the force that causes the plates to move?

gravityHeat and gravity are fundamental to the process The energy source for plate tectonics is Earth’s internal heat while the forces moving the plates are the “ridge push” and “slab pull” gravity forces. It was once thought that mantle convection could drive plate motions.

What are the three types of seafloor spreading?

There are three types of plate-plate interactions based upon relative motion: convergent, where plates collide, divergent, where plates separate, and transform motion, where plates simply slide past each other.

What happens if 2 oceanic plates collide?

When two oceanic plates converge, the denser plate will end up sinking below the less dense plate, leading to the formation of an oceanic subduction zone. … Whenever a subduction zone is formed, the subducted plate will end up being partially melted by the earth’s internal magma and molten.

Which crust sinks to the mantle because of its high density?

oceanic crustBecause it is thick and has relatively low density, continental crust rises higher on the mantle than oceanic crust, which sinks into the mantle to form basins.

Is seafloor created from and then recycled back into the mantle?

Mid-ocean ridges are structurally weak zones in the ocean floor, and where magma rises to form new oceanic crust. This process, called seafloor spreading, has built the present system of mid-ocean ridges. … Subduction zones are plate boundaries where old oceanic crust is recycled back into the mantle.

What is between the mantle and crust?

The boundary between the crust and mantle is called the Mohorovicic discontinuity (or Moho); it is named in honor of the man who discovered it, the Croatian scientist Andrija Mohorovicic. No one has ever seen this boundary, but it can be detected by a sharp increase downward in the speed of earthquake waves there.

How can you tell how old the oceanic crust is?

Scientists can determine the age of the seafloor by examining the changing magnetic field of our planet. Every once in a while, the currents in the liquid core, which create the Earth’s magnetic field, reverse themselves: it is called a geomagnetic reversal. This has happened many times throughout Earth’s history.

What is the process where the ocean floor sinks below the deep ocean trench and back into the mantle?

At some points, the oceanic crust bends downward and forms a deep-ocean trench. Then the oceanic crust sinks back into the mantle through a process called subduction. Where oceanic crust and continental crust meet and form a trench, the oceanic crust bends and sinks beneath the continent and into the mantle.

Where is the youngest oceanic crust found?

The youngest crust (shown in red) is near mid ocean ridges and spreading zones.

Is it true that a deep ocean trench is an underwater mountain?

A deep-ocean trench is an underwater MOUNTAIN. Molten material erupts INSIDE the central valley of mid-ocean ridges. The farther from a mid-ocean ridge a rock sample is taken, the YOUNGER the rock is. Sea-floor spreading occurs at MID-OCEAN RIDGES.

What are the 2 types of crust?

Earth’s crust is divided into two types: oceanic crust and continental crust. The transition zone between these two types of crust is sometimes called the Conrad discontinuity. Silicates (mostly compounds made of silicon and oxygen) are the most abundant rocks and minerals in both oceanic and continental crust.

Where is oceanic crust pulled down into the mantle?

subduction zoneTectonic plates can transport both continental crust and oceanic crust, or they may be made of only one kind of crust. Oceanic crust is denser than continental crust. At a subduction zone, the oceanic crust usually sinks into the mantle beneath lighter continental crust.

Why does the oceanic crust get pulled back down into the mantle?

Subduction zones, usually associated with deep ocean trenches, are found around the world. … As it moves down into the subduction zone, our crust is pushed down under another plate. It bends down and starts to sink into the mantle – the older the crust, the steeper the angle.

Where is the oldest oceanic crust located?

Mediterranean SeaThe world’s oldest oceanic crust – around 340 million years old – lies at the bottom of the eastern Mediterranean Sea, according to a geologist in Israel.

What is it called when the ocean floor sinks into the mantle?

The process by which the ocean floor sinks into the mantle is called Subduction ..

Which crust is thicker but with less density?

The continental crust is also less dense than oceanic crust, although it is considerably thicker. As a consequence of the density difference, when active margins of continental crust meet oceanic crust in subduction zones, the oceanic crust is typically subducted back into the mantle.