Asked by big gieger
what makes up the lithosphere
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The lithosphere is Earth’s rigid outer shell — the crust plus the uppermost solid part of the mantle — that behaves mechanically as a stiff, brittle layer and is broken into tectonic plates.
Key components and properties:
- Crust: the outermost rock layer. Continental crust is generally thick (≈30–70 km) and felsic to intermediate in composition (granite, granodiorite: rich in Si, O, Al, K, Na). Oceanic crust is thinner (≈5–10 km near ridges to ~7–10 km average) and mafic (basalt, gabbro: richer in Fe, Mg, Ca).
- Lithospheric mantle: the uppermost part of the mantle beneath the crust, composed mainly of peridotite (olivine and pyroxenes, rich in Mg and Fe).
- Thickness: total lithosphere thickness varies with tectonic setting and age — from a few tens of km (young oceanic lithosphere) to >200 km beneath old continental cratons.
- Mechanical behavior: rigid and brittle compared with the underlying asthenosphere, which is hotter and more ductile; the lithosphere–asthenosphere boundary is commonly defined by a temperature/viscosity change (often near ~1200–1400 °C in peridotite).
- Role: forms the tectonic plates that move, interact, and control earthquakes, mountain building, volcanism, and isostasy.
Main elements present: oxygen, silicon, aluminum, iron, magnesium, calcium, sodium, potassium (in varying proportions between crust and mantle).
Key components and properties:
- Crust: the outermost rock layer. Continental crust is generally thick (≈30–70 km) and felsic to intermediate in composition (granite, granodiorite: rich in Si, O, Al, K, Na). Oceanic crust is thinner (≈5–10 km near ridges to ~7–10 km average) and mafic (basalt, gabbro: richer in Fe, Mg, Ca).
- Lithospheric mantle: the uppermost part of the mantle beneath the crust, composed mainly of peridotite (olivine and pyroxenes, rich in Mg and Fe).
- Thickness: total lithosphere thickness varies with tectonic setting and age — from a few tens of km (young oceanic lithosphere) to >200 km beneath old continental cratons.
- Mechanical behavior: rigid and brittle compared with the underlying asthenosphere, which is hotter and more ductile; the lithosphere–asthenosphere boundary is commonly defined by a temperature/viscosity change (often near ~1200–1400 °C in peridotite).
- Role: forms the tectonic plates that move, interact, and control earthquakes, mountain building, volcanism, and isostasy.
Main elements present: oxygen, silicon, aluminum, iron, magnesium, calcium, sodium, potassium (in varying proportions between crust and mantle).
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