Oceanic crust being so thin is a very small fraction of the earth about 0 1 percent but its life cycle serves to separate the contents of the upper mantle into a heavy residue and a lighter set of basaltic rocks.
Why didnt granite sink down into eaths mantel.
The mantle extends down to 2 890 km into the earth s surface temperatures that range from 500 to 900 degrees celsius in the upper portion to over 4 000 degrees celsius near the core boundary.
It also extracts the so called incompatible elements which don t fit into mantle minerals and move into the liquid melt.
Unexpectedly helium hydrogen nitrogen and even carbon dioxide from microbes were found all along the borehole.
At the bottom of the mantle the material travels horizontally and is heated by the core.
The earth has gas.
It reaches the location where warm mantle material rises and the mantle convection cell is complete.
The mantle is about 2 900 kilometers 1 802 miles thick and makes up a whopping 84 of earth s total volume.
The mantle lies between earth s dense super heated core and its thin outer layer the crust.
This process also hinges on the presence of water which forms a necessary ingredient in an important early crystallizing mineral called amphibole campbell says.
It eventually becomes cool and dense enough to sink back down into the mantle.
They separate and sink down into the mantle leaving behind silica rich magma that has the right composition to form granite.