Crustal structural characteristics

Features of crustal structure: The main features of crustal structure are uneven crustal thickness, thick continental crust and thin marine crust. The marine crust lacks the Si-Al layer of the upper crust and the Si-Mg layer of the lower crust is intact.

From the earth's surface to the core, it can be divided into three levels, namely, crust, mantle and core. The crust is mainly composed of silicon and silicate rocks rich in aluminum, so it is also called lithosphere. It is a hard solid shell on the earth's surface, which provides a place for terrestrial plants to survive and move.

The crust is the outermost circle of the solid earth, which is mainly composed of silicate rocks rich in silicon and aluminum, ranging from the surface to Moho. The thickness varies greatly, and the ocean shell is thin, with an average thickness of 6 kilometers and the thinnest part less than 5 kilometers; The continental crust is thick, with an average thickness of 35 kilometers, and the thickest part can reach 70 kilometers. The average thickness of the whole crust is 17 kilometers.

The Qinghai-Tibet Plateau is the thickest part of the earth's crust, with a thickness of over 70 kilometers. The middle crust of the submarine valley in the middle of the Atlantic Ocean near the equator is only 1.6 km thick. The deep trench crust of the East Mariana Islands in the Pacific Ocean is the thinnest place on earth.

Elements in the earth's crust:

There are 1 12 elements in the periodic table of chemical elements, of which 92 elements and more than 300 isotopes exist in the crust.

Oxygen is the most chemical element in the crust, accounting for 48.6% of the total weight; Followed by silicon, accounting for 26.3%; The following are aluminum, iron, calcium, sodium, potassium and magnesium. The lowest abundance is astatine and francium, accounting for about one third of 1023. The above eight elements account for 98.04% of the total weight of the crust, and the other 80 elements account for 1.96%.

The atomic percentage of the average content of various chemical elements in the crust is called atomic Clark value, and the chemical element with the largest number of atoms in the crust is still oxygen, followed by silicon and hydrogen.

The most abundant element in the earth's crust is oxygen, but the most abundant metal element is aluminum.

Aluminum occupies 8.3% of the total crust, twice as much as iron, and about one third of the total crust metal elements.