The Layered Structure: Lithosphere and Asthenosphere To address what tectonic plates are composed of, one must first distinguish between the plate itself and the boundary below it. This rigid outer layer is mechanically strong and includes both the crust and the uppermost mantle.
How Continental Plates Differ in Composition from Oceanic Plates
It is denser, thinner, and younger than continental crust, constantly being created at mid-ocean ridges and destroyed at subduction zones. Quartz, feldspar, and mica are the hallmarks of the continental crust, making these plates lighter and more chemically complex than their oceanic counterparts.
Continental crust: This forms the landmasses and is composed predominantly of granite, a light, silica-rich rock. Understanding what the Earth’s outer shell is made of requires looking at the rigid, mobile fragments that define modern geology.
How Continental Plates Differ in Composition from Oceanic Counterparts
The Role of Oceanic Mantle and Thermal Structure Not all oceanic plates are created equal, and their composition varies with age. Continental plates, conversely, are dominated by felsic rocks, rich in silicon and aluminum.
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