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The tectonic plates of the lithosphere on Earth Earth cutaway from center to surface, the lithosphere comprising the crust and lithospheric mantle (detail not to scale). A lithosphere (from Ancient Greek λίθος (líthos) 'rocky' and σφαίρα (sphaíra) 'sphere') is the rigid, [1] outermost rocky shell of a terrestrial planet or natural satellite.
Plates in the crust of Earth. Earth's crust is its thick outer shell of rock, referring to less than one percent of the planet's radius and volume.It is the top component of the lithosphere, a solidified division of Earth's layers that includes the crust and the upper part of the mantle. [1]
Lithosphere – Outermost shell of a terrestrial-type planet or natural satellite; Ocean – Body of salt water covering most of Earth; Plate tectonics – Movement of Earth's lithosphere List of tectonic plate interactions – Types of plate boundaries; Supercontinent – Landmass comprising more than one continental core, or craton
The LAB is determined from the differences in the lithosphere and asthenosphere including, but not limited to, differences in grain size, chemical composition, thermal properties, and extent of partial melt; these are factors that affect the rheological differences in the lithosphere and asthenosphere.
The trace element composition of these xenoliths suggest mixing between the two different layers of subcontinental mantle. Particularly, the theory for the removal of Archean subcontinental lithosphere below Archean continental crust via delamination helps to explain mantle-peridotite xenoliths found in the extinct Sierra Nevada arc. [2]
Note: In chondrite model (1), the light element in the core is assumed to be Si. Chondrite model (2) is a model of chemical composition of the mantle corresponding to the model of core shown in chondrite model (1). [1] A photograph of Earth taken by the crew of Apollo 17 in 1972. A processed version became widely known as The Blue Marble. [2] [3]
The chemical composition of the mantle is difficult to determine with a high degree of certainty because it is largely inaccessible. Rare exposures of mantle rocks occur in ophiolites, where sections of oceanic lithosphere have been obducted onto a continent. Mantle rocks are also sampled as xenoliths within basalts or kimberlites.
The composition of the Earth changed after its formation due to loss of volatile compounds, melting and recrystalization, selective loss of some elements to the deep interior, and erosion by water. [ 3 ] : 55 The lanthanides are especially difficult to measure accurately.