The moon is the earth's satellite . According to the large collision hypothesis, the moon was formed in a large collision event, and the high-energy substance ejected remained in orbit around the earth, and finally accretion formed the moon. The lunar core mantle quickly separated in the early stage, and global magma melted, forming a magma sphere (magma ocean). The crystallization and solidification of the magma ocean lead to the formation of the lunar crust. In the evolutionary history of the late moon, impact action is the most important geological effect, forming multi-scale and multi-period impact basins and impact craters, while large impact basins are mostly formed in the early stages of lunar evolution.
Figure 1, the moon surface is potholes
1. Overview of the moon
The moon is the Earth's satellite, orbiting the earth. In type of earth planet , the moon is the best object to study multi-ring basins. On the one hand, many early features are preserved due to their relative primitiveness. On the other hand, the moon's exploration data and samples are much richer than other planets. Among them, the image data can clearly identify morphological features related to basin sedimentation and structure.
Figure 2, Minerals, geochemical , and geophysical data obtained from the interpretation of remote sensing data of moon
can be used to infer the regional chemical composition and rock characteristics of basin sputters, and provide clues about the temperature and pressure conditions of the impact process.
Figure 3, lunar surface
lunar research has obtained massive data, and more and more accurate data is still accumulating. How to summarize and summarize the obtained data and obtain information on the formation and evolution process of the moon based on these data is a scientific issue worthy of in-depth research.
Figure 4, astronauts in outer space
2. Moon evolution
For the history of lunar evolution, the large collision event that formed the moon, the evolution of the lunar magma ocean, and the large-scale impact event that excavates the surface of the moon to form the moon sea basin are the three most important geological events.
Figure 5, meteorite impact
First of all, the moon is likely to be formed in a large collision event, which is the starting point and basis of the moon's evolution. There are various hypotheses about the formation of the moon, such as homology, division theory, capture theory, and large collision, among which the large collision hypothesis is widely accepted.
Figure 6, meteorite
According to this hypothesis, the composition of the initial material of the moon has undergone great changes in this event, including the high-temperature silicate melt and gas may undergo strong evaporation, causing a large amount of water and volatile components to be lost, a considerable part of the material comes from the original earth, and most of the metals are added to the earth, etc.
Figure 7, asteroid
At the same time, the energy of the large collision makes the moon form a very deep global magma ocean, and the latter's differentiation crystals largely determine the internal structure of the moon and the lunar surface binary structure.
3. Rocks and minerals of the moon
According to the large impact hypothesis of the origin of the moon, the nuclear mantle formed by the impact quickly separated the nuclear mantle in the early stage, and global magma melted, forming a magma ocean of about 400km or even deeper. According to the characteristics of the returned samples, the Apollo era proposed the idea that the plagiarite lunar crust is differentiated from magma and floats on the moon's surface. These views then perfected the now popular "lunar magma ocean hypothesis".
Figure 8, astronauts collected samples
magma ocean crystallization and solidification led to the formation of html January mantle . A classic model of magma ocean evolution believes that the earliest crystallizations were peridot and pyroxene , which were accumulated in the lower part of the moon mantle due to gravity, and were composed of pure peridotite and square peridotite.
Figure 9, basalt
When the crystallization degree of the magma ocean reaches about 80%, that is, the composition of the magma ocean reaches the solid phase line of plagioclase , the plagioclase begins to crystallize. Due to its small density, the feldspar floats up during the magma differentiation process, forming a 40-45km thick plagioclase lunar crust on the surface of the moon.
Figure 10, plagiarite
When the crystallization degree of magma ocean reaches about 95%, ilmenite begins to crystallize.As the magma ocean continues to solidify, the lunar crust and the lunar mantle continue to differentiate, and the content of incompatible elements in the residual magma gradually increases, and finally, krip rock (KREEP) enriched between the lunar mantle and the lunar crust is formed.
Figure 11, ilmenite
Since the density of ilmenite is greater than that of silicate minerals, in the late magma oceanic differentiation, the crystal layer formed on the upper part of the lunar mantle has gravity instability, and it sinks to the lower part of the lunar mantle through material convection, mixing with the previously accumulated silicates, thus forming an uneven lunar mantle.
Figure 12, sodium silicate
4. The impact of the moon on humans
On the earth, through the study of geological structure, we can master the occurrence, development and termination process of tectonic movements at different scales, and understand the impact of this process on the earth's morphology, mineral resources, environment and life evolution.
Figure 13, Moon
In the research on planetary geology represented by moon research, although there are great differences in research methods and means, the study of the geological structure phenomena on the surface of planets also helps us understand the structure, formation and evolution of planets and their relationship with the earth. In particular, the evolution of the moon has basically ended 3 billion years ago, and the first 800 million years of the moon's formation has been well preserved, and the records of this evolutionary history on the earth have been wiped out.
Figure 14, solar system
. On the other hand, it is precisely because the moon retains records of early geological evolution that the moon also retains the entire history of the occurrence and development of solar system impact events. Therefore, the study of the lunar geological tectonic lattice and its evolutionary history can demonstrate two dynamic processes of solar system evolution, namely, the impact events of the moon can reflect the process of external dynamic geological action.
Figure 15, meteorite impact
, and the lunar magma ocean evolution and lunar crust formation and later magma and volcanic action can reflect the process of internal dynamic geological action. These important geological processes are not only the main process of forming the moon, but also the process of the formation of other terrestrial planets in the solar system, which plays an important role in restricting the evolution of the moon and the later planets.
Figure 16, Magma
To sum up: The origin and evolution of the moon are a major scientific issue that is interdisciplinary and cross-field. Solving this problem requires the collaborative completion of many disciplines using advanced means. It is impossible for any individual discipline or researcher to have all the knowledge and skills, so that they can be competent and completed independently.
