Diamond knows when the movement of the Earth continent continues

BySteven Depolo

Assuming that the earth's crust is moving on the mantle of the soft layerPlate tectonicsIs widely accepted as a theory to explain the formation of each continent and the mechanism of earthquake occurrence. However, I did not know when the plate tectonics began, and it was where there was debate. Meanwhile, research results that use "diamond" to infer the origin of plate tectonics have been announced and attracting attention.

Early Archaean tectonics and mantle redox recorded in Witwatersrand diamonds: Nature Geoscience: Nature Publishing Group
http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo2628.html

Diamonds used to "probe" ancient Earth - Wits University
https://www.wits.ac.za/news/latest-news/research-news/2016/2016-01/diamonds-used-to-probe-ancient-earth.html

Once there is one supercontinent "Pangea" on Earth, it is said that it has split and became the current continentContinental movement theory"Alfred WegenerAt the time that was advocated, I could not explain exactly what the dynamics the continent moved and it was not supported at all. However, in the latter part of the 20th century, after the idea of ​​plate tectonics that the interior of the earth has a different layered structure and the hard and thin crust is sliding on a relatively soft mantle is devised, It became widely accepted as being able to explain the mechanism of the earthquake as well as its origins. After that, it became confirmed that the continent is moving when it becomes possible to observe the datum accurately by the artificial satellite, and the continental movement theory and the plate tectonics are now common as the theory to explain the mechanism of the earth.


The existence of plate tectonics itself was accepted, but as to when it began,ArcheanAlthough it was mainstream that it was somewhere in the world (4 billion years ago to 2.5 billion years ago), it was not clearly understood. Meanwhile, a research group centered on Dr. Katie Smart of South Africa's University of Witwatersland said that the paper "estimated at least 3.5 billion years ago"Nature GeoscienceIt is announced in.

Dr. Smart focused on diamonds which are known as physically and chemically stable substances. Since diamonds exist stably, it is known that they function as a so-called "time capsule" that records the events occurred in the ground, and the state of the past using such diamonds It seems that research that presumes is not unusual.

Research group, South AfricaKarp Bar KrathongI borrowed three specimens of the oldest diamond in the world, mined from the African Museum in Johannesburg. And by measuring radioactive dating, we found that rocks containing diamonds (host rock) were born 3.1 billion years ago from 3.5 billion years ago.

After that, Dr. Smart replied the isotopic composition ratios of nitrogen 15 / nitrogen 14, carbon 13 / carbon 12 among the components inside the diamond, so that the crust in the crust near the surface of the earth, rather than inside the mantle crystallized with diamond, We found out that 15 isotopes were doped (added). In other words, this means that diamond was drawn into the ground by movement of plate tectonics, "Plate tectonics started as early as 3.5 billion years ago" on the origin of plate tectonics I have concluded.