LITHOSPHERE

What is it basically?

1. The solid shell of a rocky planet called earth. That means the crust and the upper part of the mantle which is joined to the crust.
2. Approximately 100 km (62 mi.) thick.
3. Under the lithosphere there is the asthenosphere, the weaker, hotter, and deeper part of the upper mantle.

Earth's crust : Lithosphere

Types of lithosphere.

1. Oceanic lithosphere, which is associated with Oceanic crust:

• Typically about 50-100 km thick (but beneath the mid-ocean ridges is no thicker than the crust).
  
• Consists mainly of mafic crust and ultramafic mantle and is denser than continental lithosphere, for which the mantle is associated with crust made of felsic rocks.
  
• Thickens as it ages and moves away from the mid-ocean ridge.
  
• Constantly being produced at mid-ocean ridges and is recycled back to the mantle at subduction zones.
  
• Much younger than continental lithosphere: the oldest oceanic lithosphere is about 170 million years old, while parts of the continental lithosphere are billions of years old.
  

2. Continental lithosphere, which is associated with Continental crust:

• Is thicker (about 150 km).
• It consists of about 50 km of crust and 100 km or more of uppermost mantle.
  
• The layer of granitic, sedimentary, and metamorphic rocks which form the continents and the areas of shallow seabed close to their shores, known as continental shelves.
  
• Also less dense than oceanic crust, though it is considerably thicker; mostly 35 to 40 km versus the average oceanic thickness of around 7-10 km. About 40% of the Earth's surface is now underlain by continental crust.
  

How about Chemical lithosphere?

Defined as a chemical boundary layer between the surface of the Earth and the asthenosphere that cools by conduction and contains both the material differentiated or extracted from the mantle (for example, oceanic and continental crust) and mantle material modified by various degrees of depletion.