What is the composition and approximate thickness of the mantle? (site 1)
The mantle is composed mainly of silicate rocks rich in iron and magnesium. Its approximate thickness is about 2,900 kilometers.
Step 1: The mantle is the layer of Earth located between the crust and the outer core. It constitutes about 84% of the Earth's total volume.
Step 2: The mantle is primarily composed of silicate rocks rich in magnesium and iron. The main minerals found in the mantle include olivine, pyroxene, and garnet.
Step 3: The mantle can be further divided into two main regions: the upper mantle and the lower mantle.
Step 4: The upper mantle, which extends from the crust to a depth of about 410 kilometers (250 miles), is mainly composed of peridotite. Peridotite is a dense rock consisting primarily of olivine and pyroxene minerals.
Step 5: The lower mantle starts below the upper mantle and extends down to the core-mantle boundary at a depth of about 2,900 kilometers (1,800 miles). It is composed mainly of a different form of peridotite called bridgmanite, which is stable at higher pressures found in the lower mantle.
Step 6: The average thickness of the mantle is approximately 2,900 kilometers (1,800 miles), but this thickness can vary based on the location and geological activity in different regions of the Earth.