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The thickness of Earth's crust (km). The continental crust consists of various layers, with a bulk composition that is intermediate (SiO 2 wt% = 60.6). [5] The average density of the continental crust is about, 2.83 g/cm 3 (0.102 lb/cu in), [6] less dense than the ultramafic material that makes up the mantle, which has a density of around 3.3 g/cm 3 (0.12 lb/cu in).
Oceanic: 5 - 10 km (3 - 6 mi) thick [5] and composed primarily of denser, more mafic rocks, such as basalt, diabase, and gabbro. The average thickness of the crust is about 15 - 20 km (9 - 12 mi). [6] Because both the continental and oceanic crust are less dense than the mantle below, both types of crust "float" on the mantle.
In contrast, continental crust is thick (~45 km thick) and buoyant, composed mostly of granitic rocks (average density about 2.5 g/cm 3). Continental crust is subducted with difficulty, but it is subducted to depths of 90-150 km or more, as evidenced by ultra-high pressure (UHP) metamorphic suites. Normal subduction continues as long as the ...
The only known example of tertiary crust is the continental crust of the Earth. ... The thickness of the crust ranges between about 20 and 120 km. Crust on the far ...
Continental lithosphere has a range in thickness from about 40 kilometres (25 mi) to perhaps 280 kilometres (170 mi); [3] the upper approximately 30 to 50 kilometres (19 to 31 mi) of typical continental lithosphere is crust.
Continental crust is about 35 km (22 mi) thick, but the large crustal root under the Tibetan Plateau is approximately 70 km (43 mi) thick. [4] The thickness of the upper mantle is about 640 km (400 mi). The entire mantle is about 2,900 km (1,800 mi) thick, which means the upper mantle is only about 20% of the total mantle thickness. [4]
Tectonic plates are pieces of Earth's crust and uppermost mantle, together referred to as the lithosphere. The plates are around 100 km (62 mi) thick and consist of two principal types of material: oceanic crust (also called sima from silicon and magnesium) and continental crust (sial from silicon and aluminium).
Lithosphere underlying ocean crust has a thickness of around 100 km (62 mi), whereas lithosphere underlying continental crust generally has a thickness of 150–200 km (93–124 mi). [5] The lithosphere and overlying crust make up tectonic plates, which move over the asthenosphere. Below the asthenosphere, the mantle is again relatively rigid.