Distribution characteristics of crustal thickness

The characteristics of crustal thickness distribution are introduced as follows:

There are significant differences in the distribution characteristics of crustal thickness in different regions. Generally speaking, the continental crust is thicker and the oceanic crust is thinner. The continental crust is usually 30-70km thick, while the marine crust is only about 5 5- 10/0km thick. ?

The main feature of crustal structure: discontinuous distribution of silicon and aluminum layers.

The crust is the outermost layer of the earth's solid surface structure, and the average thickness of the whole crust is about 17 km, of which the continental crust is relatively thick, with an average thickness of about 39-4 1 km. The crust of mountains and plateaus is thick, up to 70 kilometers; The crust of plains and basins is relatively thin. The ocean crust is much thinner than the continental crust, only a few kilometers thick. The Qinghai-Tibet Plateau is the thickest part of the earth's crust, with a thickness of over 70 kilometers. The thickness of the middle crust of the submarine valley near the equator in the middle of the Atlantic Ocean is only 1.6 km. The deep trench crust in the eastern part of the Mariana Islands in the Pacific Ocean is the thinnest place on earth.

Archean crustal movement and magmatic activity are both extensive and intense, and frequent volcanic eruptions have led to the formation of the atmosphere and hydrosphere. The area of primitive ocean may be larger than we know, but the average water depth is much shallower. During this period, metamorphic iron-manganese deposits rich in marine layered deposits and gold deposits formed by magmatic activities were formed all over the world. The atmosphere at that time may be rich in carbonic acid gas, water vapor and volcanic ash, with only a small amount of nitrogen and abiotic oxygen. Seawater is also acidic mineralized water, and the land is hot and barren.

Since its formation, the earth's crust has been moving, which leads to the continuous change of its structure. Earthquakes are the reflection of the crustal movement that people directly feel. Generally, the crustal movement lasts for a long time and is slow, so it is difficult for people to detect it. It can only be detected by long-term observation of instruments. For example, geodetic data prove that the Himalayas are still rising at a rate of 0.33~ 1.27 cm per year.