How did the coal resources in Shanxi come into being?

Shanxi province used to have a warm and humid climate and dense forests. Later, the crust moved and the vegetation was buried underground. After a long evolution, rich coal resources have been formed.

Causes of coal formation

Coal is a very thick layer of black humus, which has been accumulated on the ground by the branches and roots of plants for millions of years. Due to the change of the earth's crust, it has been buried underground for a long time and isolated from the air. After a series of complex physical and chemical changes at high temperature and high pressure, a black combustible sedimentary rock is formed, which is the formation process of coal.

The thickness of coal seam in coal mine is related to the speed of crustal decline and the accumulation of plant residues in this area. The earth's crust is falling rapidly and the plant remains are piled thick, so the coal seam in this coal mine is thick. On the contrary, the earth's crust is slowly falling, and the plant remains are piled very thin, so the coal seam of this coal mine is very thin. Due to the tectonic movement of the earth's crust, the original horizontal coal seam was folded and fractured. Some coal seams are buried deep underground, while others are pushed out of the surface or even exposed to the ground, which is easy to be found. There are also some coal seams that are relatively thin and small in area and have no mining value. So far, there is no updated statement about the formation of coal.

Is coal formed in this way? Whether some expositions should be further studied and discussed. Large coal mines have thick coal seams and excellent coal quality, but the area is generally not very large. If the leaves and roots of plants have accumulated naturally for millions of years, their area should be very large. Because the earth was full of forests and grasslands in ancient times, there should be traces of coal storage everywhere underground; The coal seam is not necessarily very thick, because the leaves and roots of plants rot into humus, which will be absorbed by plants. If it is repeated, it will not be so concentrated when buried underground, and the boundary between soil layer and coal seam will not be so clear.

However, the undeniable fact and basis is that coal is indeed formed by the systematic evolution of plant residues, which is an unbreakable truth. As long as you look at the coal carefully, you can see the traces of leaves and roots of plants; If you slice coal and observe it under a microscope, you can find a very clear plant tissue structure. Sometimes things like tree trunks are still preserved in coal seams, and some coal seams are still wrapped with complete insect fossils. Under the normal temperature and pressure of the surface, the plant residues accumulated in stagnant water are transformed from peat or sapropelic mud into peat or sapropelic mud; After peat or sapropelic mud is buried,

Due to the depression of the basin basement, it sank deep underground and was transformed into lignite by diagenesis. When the temperature and pressure gradually increase, it is transformed into bituminous coal to anthracite by metamorphism. Peatization refers to the process that the remains of higher plants accumulate in swamps and are transformed into peat through biochemical changes. Sapropargization refers to the process of transforming the remains of lower organisms into sapropelic mud through biochemical changes in swamps. Asphaltene is a kind of argillaceous material rich in water and asphaltene. Glaciation may contribute to the collection and preservation of coal-forming plant remains.