upper mantle

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Part of the mantle

mantle Part of Level B ( Moho surface ~400 km) and Layer C (400~670km), once called Eclogite sphere 。

Chinese name: upper mantle

Foreign name: Upper Mantle
Name used before: Eclogite sphere

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Basic Introduction

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upper mantle ； outer mantle

In addition to silicon and oxygen, iron and magnesium increased significantly, and aluminum took the second place Peridotite Of Ultrabasic rock Composition, average density 3.8 g/cm ^ 3, pressure about 1.2~1.35 GPa, temperature 400~3000 ℃, solid state Crystalline , but with greater plasticity; seismic wave Of P-wave The speed is about 8.10 km/s, S-wave The speed is about 4.7 km/s.

Solid Earth Structure Table

Earth sphere name				depth (km)	earthquake Longitudinal wave velocity (km/s)	earthquake Shear wave velocity (km/s)	Density (g/cm3)	material state
class a layered	second level layered		tradition layered	depth (km)	earthquake Longitudinal wave velocity (km/s)	earthquake Shear wave velocity (km/s)	Density (g/cm3)	material state
Outside The Ball	Crust		Crust	0—33	5.6—7.0	3.4—4.2	2.6—2.9	Solid matter
	Outside too Ferry layer	Outer transition layer (I)	upper mantle	33—980	8.1—10.1	4.4—5.4	3.2—3.6	part Molten material
	Outside too Ferry layer	Outer transition layer (B)	Lower mantle	980—2900	12.8—13.5	6.9—7.2	5.1—5.6	Solid liquid substance
liquid state layer	Liquid layer		Field nuclear	2900—4700	8.0—8.2	Unable to pass	10.0—11.4	Liquid substance
within The Ball	Introgression Degree layer		Transition layer	4700—5100	9.5—10.3	Unable to pass	twelve point three	Liquid solid substance
within The Ball	earth 's core		Inland nuclear	5100—6371	10.9—11.2	Unable to pass	twelve point five	Solid matter

Substance composition

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upper mantle

whole mantle Material composition, generally considered to be related to Chondrite Similar, that is, iron, magnesium silicate Mainly. According to high temperature High pressure test Data infer that the upper mantle Level B with olivine The structure is dominated by iron magnesium silicate, Silica tetrahedron Distributed in islands metal ion It is also called island silicate. to Layer C , iron magnesium silicate becomes Spinel structure Is a feature. Below 670km Perovskite structure It is characterized by iron magnesium silicate. In the mantle silicate There may be a small amount of fluid (i.e. nitrogen halogen 、 alkali metal , carbon, oxygen, helium, sulfur), which is called mantle juice, causes mantle thermal convection mantle The internal temperature changes slightly, and the average temperature increases by only about 1 ℃ for every 1 km downward.

Relevant information

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according to geophysical And geological research results show that there is a Discontinuity Low velocity zone ， seismic velocity (vP) At a depth of 60 km, it drops from 8.2 km/s to 7.7 km/s at a depth of 150 km, and then rises to 8.2 km/s at a depth of 250 km, belonging to Asthenosphere , the rock may have local melting. transverse wave VS dropped from the corresponding 4.6 km/s to 4.0 km/s. The heat is about (1.1~1.5) × 10 ^ 31 coke, which is higher than the melting point of the material at this depth, and the local part is in melting or softening state. It is generally believed that this may be Basicity or Hyperbasicity Magma It is called asthenosphere because of its origin. Deep focus earthquake It also occurs in the upper mantle, up to 720km deep. Therefore, the research on the upper mantle has been paid more and more attention and has made great progress.

The thickness is 20-400km. seismic wave The gradient of velocity increases with depth in its interior is small, between 60 and 150 kilometers, many Oceanic region And late stage Orogenic belt There is a low speed layer inside, which may be caused by mantle material partial melting Caused by.

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