Understanding what the Earth’s outer shell is made of requires looking at the rigid, mobile fragments that define modern geology. 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.
Composition of Oceanic Crust: The Mafic Rocks Beneath the Tectonic Plates
As it ages and moves away from the ridge, it cools and thickens. Plate Type Primary Crustal Rock Primary Mantle Rock Key Minerals.
The composition remains largely basaltic and peridotitic, but the physical state changes from a flexible layer to a strong, rigid lid capable of supporting the weight of continents or resisting the pull of subduction. Oceanic plates are dominated by mafic rocks, which are rich in magnesium and iron.
Composition of Oceanic Crust: The Mafic Rocks Dominating Tectonic Plates
Below this rigid layer lies the asthenosphere, a zone in the upper mantle that behaves ductilely and allows the plates to move. Continental crust: This forms the landmasses and is composed predominantly of granite, a light, silica-rich rock.
More About What are tectonic plates composed of
Looking at What are tectonic plates composed of from another angle can help expand the discussion and give readers a second clear paragraph under the same section.
More perspective on What are tectonic plates composed of can make the topic easier to follow by connecting earlier points with a few simple takeaways.
