2022-10-25 10:21·Science and Technology Daily
Intern Reporter Zhang Jiaxin
A study on the oldest rock fragments on the earth provides some of the most powerful evidence to date, indicating that at least 3.25 billion years ago, the Earth's crust was pushing and pulling in a way similar to modern plate tectonics. This study also provides the earliest evidence of when the Earth's north-south magnetic poles interchange positions. The clues provided by these two results give people an understanding of how these geological changes lead to more favorable environments for life development on Earth.
Internal profile of the early Earth highlights its main geodynamic process. Source: Harvard University geologist Alec Brenner
This study was led by Harvard University geologists Alec Brenner and Roger Fu, and the research results were published in the Proceedings of the National Academy of Sciences . Using new technologies and equipment, researchers show that some of the earliest crusts on Earth move at a rate of 6.1 cm per year and 0.55 degrees per million years.
This speed is more than twice the speed of ancient crust movement shown in a previous study. The velocity and direction of this zonal drift make the plate structure the most reasonable and powerful explanation of it.
In this paper, scientists also describe what is believed to be the oldest evidence of when the Earth reverses the geomagnetic field , which means that the positions of magnetic north pole and magnetic south pole have been flipped. This type of flip is common in the history of geogeology, with geomagnetic fields flipped 183 times in the past 83 million years; in the past 160 million years, the geomagnetic fields may have flipped hundreds. This flip of
reveals a lot of information about the geomagnetic field 3.2 billion years ago. The key point is that the magnetic field may be stable and powerful enough to prevent solar wind from eroding the atmosphere. This discovery, combined with plate tectonic results, provides clues to understanding the conditions for the development of the earliest life forms.
"It depicts a picture of the early Earth, which is already very mature in geodynamics," Brenner said. "It has many of the same dynamic processes that lead to the Earth having more stable environmental and surface conditions, making life more feasible to evolve and develop."
Overall, this study complements a growing number of studies that tectonic motion occurred in relatively early times of the Earth's 4.5 billion years of history, with early life forms appearing in more milder environments.
[Editor General Circle]
On the scale of geological time, the history of human civilization seems insignificant. But it was humans who appeared in such a short period of time that they had been trying to explore what happened on the original earth. We know that the magnetic poles of the earth have been flipped hundreds of times in the past, and research on the magnetic fields of rocks in different eras can prove this. plate tectonic theory is well known, but how the earth's crust moved many years ago and what results these movements have produced remains to be explored. As the text says, the oldest fragments of the earth's crust are hard to detect, and humans can only search for the past from the available ancient rocks as much as possible and form a puzzle of earth's dynamics from billions of years ago.
Editor: Zhang Qiqi
Review: Yue Liang
