Russian scientists have proved that fragments of the modern Arctic shelf have formed a single continental space at least twice in the history of the Earth. For the first time about a billion years ago, the ancient continent of Arctida was part of the supercontinent Rodinia. The second time - 250 million years ago - Arctida was part of Pangea. The study was carried out using the paleomagnetic method, which makes it possible to reconstruct the paleogeography and kinematics of the movements of individual blocks of the continental lithosphere.
Look into the past
Scientists of the Institute of Oil and Gas Geology and Geophysics named after A. A. Trofimuk SB RAS studied rock samples from the Arctic archipelagos, including Franz Josef Land, Novaya Zemlya, Severnaya Zemlya, Novosibirsk Islands, which made it possible not only to look into the past millions of years ago, but also to substantiate the block structure of the modern continental shelf of Russia and its boundaries.
- For the layman, the concept of “continent” corresponds to the concept of “land”, - explains Dmitry Metelkin, Professor of the Russian Academy of Sciences, Doctor of Geological and Mineralogical Sciences, Chief Researcher of the Laboratory of Geodynamics and Paleomagnetism of the Institute of Geophysics and Geology, SB RAS. - But for geologists, the concept of “continent” also includes its submerged edge - the shelf. The main thing in geology is what exactly the lithosphere (the upper solid shell of the Earth) of this particular area of the earth's surface consists of. We distinguish between the lithosphere of the continental and oceanic types - they are different in their composition, structure and characterize different parts of the continents and the ocean floor. The continental lithosphere is predominantly granite, contains many silicates or glass, and the composition of the oceanic crust primarily includes basalt.
In this 1570 map, Hyperborea is shown as an arctic continent and described as Terra Septemtrionalis Incognita (Unknown Northern Land).
The paleomagnetic method makes it possible to determine the location of lithospheric blocks and their movement in space millions of years ago. Thus, the analysis of numerous samples from the islands of the Arctic archipelagos made it possible to study the "biography" of ancient Arctida, a continent that supposedly existed in the distant geological past.
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Twice Arctida
It became clear that the continent really existed, and met twice. The lithospheric blocks that today form the continental shelf were brought together a billion years ago, when the Earth was inhabited mainly by microorganisms, which left almost no traces of their life. Arctida was then part of the supercontinent called Rodinia. About 750 million years ago, the continent completely disintegrated into separate fragments separated by oceanic space.
The second time Arctida was formed about 250 million years ago - then the first dinosaurs appeared on Earth. Arctida became part of the new supercontinent - Pangea. At the time of the collapse of Pangea and a little later, during the formation of the Arctic Ocean, fragments of the second Arctida were redistributed again, forming the modern shelf.
“The Arctida included at least five large lithospheric blocks,” says Dmitry Metelkin. - Now they are all part of the Arctic continental shelf. Our paleomagnetic method allows us to reconstruct the kinematics of their mutual movements in the past - the scales are very significant, since we study intervals of hundreds of millions of years. For example, our Eurasian continent also consists of two very large ancient lithospheric blocks: East European and Siberian. So the Siberian block was in the equatorial region about 500 million years ago. The speed of movement of the continents is negligible - only a few centimeters a year, but over hundreds of millions of years they cover really great distances.
The myth of Hyperborea
If we consider the ancient Greek myth about Hyperborea - the legendary northern country and the habitat of the Hyperboreans, about which the ancient Roman scientist Pliny the Elder wrote, then it remains a myth.
“The hypothesis that Hyperborea was located on the ancient Arctida does not stand up to criticism,” says Nikolai Matushkin, Ph. D. - We are talking about a geological body that existed hundreds of millions of years ago - it is clear that there could be no civilization at that time. Our research also refutes the well-known map of 1595 by the Flemish cartographer and geographer Gerard Mercator.
For their research, scientists from the Institute of Geological and Geological Exploration SB RAS use the methods of magnetotectonics (a specific section of paleomagnetology) - a science that studies the movements of blocks of the lithosphere on the basis of information about the direction of natural remanent magnetization of rocks, which they are composed of. The collection of samples, which now number in the thousands, has been going on for about 20 years.
- In their works, colleagues prove that some areas of the bottom of the Arctic Ocean, which are adjacent to the shelf of Eurasia and extend almost to the very North Pole, are of continental origin. They work in unexplored and extremely inaccessible areas with a harsh climate - this is a breakthrough research, - explains Doctor of Geological and Mineralogical Sciences, Professor of the Department of Dynamic Geology of the Geological Faculty of Moscow State University. M. V. Lomonosov Roman Veselovsky. - The result of this work may be the recognition of the belonging of a number of geological structures of the bottom of the northern seas to the shelf of our country. It is clear that this will be so or not - politicians will decide, but scientists can provide arguments in favor of this.
It is possible that it is the interest of politicians that pushes scientists around the world to study the continental margin of the Arctic Ocean.
Anna Urmantseva
