Tectonic plates consist of the lithosphere,or the crust and the upermost mantle?

Question

is this true or false?

Answer 1

From top on the earth

1.Crust where we live.The thickness is about 30 k/m at continent and as low as 5 k/m in deep ocean.

2.Next is lithosphere about 20 to 100 k/m thick.Made out of solid rock.Here we have broken parts called tectonic plates.

3.Asthenosphere .It is semi solid .

Next comes the other liquid and solid mandrels.

Answer 2

Tectonic plates = lithosphere, and the lithosphere = brittle crust and the uppermost brittle mantle.

The confusion arises because there are Seismologists and Geochemists. Lithosphere and Asthenosphere refer to changes in the mechanical properties of the Earth (seismology). Whereas, Crust and Mantle refer to the chemical changes within the Earth (geochemistry).

Mechanically speaking, Seismologists define the Lithosphere as the hard & ridged outer ~100 km of the Earth. The Lithosphere includes the Crust (more on it below) and the uppermost (<1300 Celsius) brittle Mantle. Below the brittle Lithosphere (Crust+upper brittle Mantle) is the Astenosphere, a weak plastic layer within the upper Mantle below, the Astenosphere is defined as having a temperature >1300 Celsius. The Astenosphere is plastic, it permits plate tectonics, the brittle Lithosphere (Crust+upper brittle Mantle) slides over the weak Astenosphere.

Compositional speaking, Geochemists defines the Crust as a chemically distinct layer of the Earth that is rich in Silicon, O, Al, Ca, K, Na, and it is divided into two types, the Continental Crust and the Oceanic Crust. The Oceanic Crust has less Silicon and more Magnesium then the Continental Crust. The Mantle has even less Silicon that Oceanic Crust and it is mainly made of Olivine and Pyroxene. The Crust and Mantle are separated by the MOHO, denoted by a sudden increase in the velocity of seismic waves (P-waves).

Answer 3

False, the plates sit on top of the mantle