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The history of the earth is long and fascinating, and scientists uncover many hidden pasts by exploring the magnetism in sediments.Through the study of paleomagnetics, geophysicists can read the wisdom in ancient strata and reveal major events such as continental drift and earth's magnetic field flip.This article will take us deep into the magnetism hidden in the soil and explore how sediments become recorders of the earth's transformation.
The core concept of paleomagnetics
Paleomagnetism studies prehistoric earth magnetic fields recorded in rocks, sediments or archaeological materials.Certain magnetic minerals, such as magnetite, are able to record the direction and intensity of the Earth's magnetic field when they form.This record not only provides information on the past behavior of the geomagnetic field, but also reveals the history of the tectonic plate.
The development of paleomagnetics not only revived the continental drift hypothesis, but also promoted the formation of modern plate tectonic theory.
The historical origins of paleomagnetics
As early as the 18th century, people noticed that the compass was shifted near the strongly magnetized formation.Over time, scientists gradually uncovered the changes in Earth's magnetic field and found that some of the recent lava flows parallel to Earth's magnetic field.Soon after, more research showed that many rocks magnetize opposite to Earth's magnetic field.In the 1930s, Japanese geophysicist Kiy Matsuyama proved for the first time that the Earth's magnetic field had flipped in the Mesoquaternary period, which is now called the "Brenhes-Matsuyama Reversal."
As Het invented the sensitive shadowless magnetometer, paleomagnetics has developed importantly and contributed to the recovery of continental drift theory.
The main principles of paleomagnetics
The study of paleomagnetics relies on some specific principles, especially iron minerals such as chromium magnets that can record the polarity of the Earth's magnetic field in the past.When the rocks cool, these iron minerals may retain the direction of the Earth's magnetic field.Among them, several important magnetization mechanisms have been widely studied:
Thermal residual magnetization: When the rock cools to a certain temperature, the direction of the earth's magnetic field at that time will be retained in the mineral.Deposition residual magnetization: Shortly after the deposition process or deposition, magnetic particles will alignate with the direction of the earth's magnetic field to form magnetization.Chemical residual magnetization: Magnetic particles grown in chemical reactions record the direction of the magnetic field at that time.
Application of paleomagnetics
The discovery of paleomagnetics is crucial to understanding the history of the earth.Paleomagnetic evidence not only helped verify the theories of continental drift and plate tectonics, but was also used to reconstruct the deformation history of the Earth's crust.The researchers used paleomagnetic data and chronological methods to determine the absolute age of the rocks that retained magnetic records, which provided important information for studying the changes in the ancient environment and climate.
By understanding the paleolatitude of fossils, scientists can obtain valuable information about the geological environment during sedimentation.
Conclusion
Paleomagnetics allows us to see the past and interpret stories buried deep in the soil.With in-depth research on paleomagnetic forces, scientists have gradually pieced together puzzles of the history of the earth.In the future, how will scientists use paleomagnetics to uncover the mysteries of more Earth and other solar system objects?
