The celestial body, from a fragment of which the Buddha statue was made, was again subjected to unearthly tests in the laboratory
The Chinge iron meteorite, which, according to one version, fell to Earth about 15 thousand years ago, was again forced to “fly by” through the «solar system» Russian scientists from the Institute of Geochemistry and Analytical Chemistry named after. V.I. Vernadsky RAS with colleagues from Snezhinsk. They conducted an impact-explosive experiment, recreating possible collisions that the celestial body experienced before falling on our planet. In fact, for the first time, scientists have assessed the extent of impact changes in an ancient meteorite. About how the experiment went, «MK» said one of the authors of the work, Doctor of Physical and Mathematical Sciences Natalya Bezaeva.
Chinge meteorite
The story goes that Chinge — an iron ataxite meteorite (a rare type of iron meteorite) weighing 250 kilograms was found on the Urgailyk-Chinga River, on the territory of the modern Republic of Tyva in 1912. Since then, more than a hundred fragments of this meteorite with a total mass of 184 kilograms have been collected, some reaching tens of centimeters in size. It was from this meteorite that the statue of Buddha-Vaishravan “Iron Man” was made at one time. weighing about 10 kilograms.
Iron meteorites coming to us from the asteroid belt are their fragments. Colliding with other bodies during travel, experiencing strong impacts and associated high-temperature effects, asteroid fragments change their structure and properties. By studying this metamorphism, scientists are essentially studying the prehistory of the evolution of solid matter in our solar system.
Slip stripes discovered in Ching after an experiment on earthly testing ground. Provided by GEOKHI.
In GEOKHI we went further – decided simulate cosmic collisions and changes in the physicochemical properties of meteorite iron using a small fragment of the Chinge meteorite available in the GEOKHI collection.
– A ball with a diameter of 57 millimeters was made, which was exposed to a shock wave converging towards the center – explains Leading researcher at the Laboratory of Meteoritics and Cosmochemistry, Deputy Director of the Geochemical Institute of the Russian Academy of Sciences Natalya Bezaeva.
– Colleagues from the Russian Federal Nuclear Center VNIITF in Snezhinsk helped us recreate tests that bordered on space tests. They placed the spherical sample in a sealed case in which a vacuum was created. Then the hermetic cover was lined with explosives on all sides and detonated. In this way, a shock wave was generated, converging from all points of the ball towards the center. Having reached a maximum in the center, it also began to diverge symmetrically towards the periphery. And when our colleagues returned our sample, we discovered that it had formed a cavity with a torn edge. This happened due to the special geometry of the shock waves. It turns out that we gave them a whole ball, and returned to us a ball with a hole (the interlocutor smiles). In addition, the sphere diverged slightly in diameter.
Chinge meteorite plate after an explosion at the test site. As a result of the shock-explosive experiment, a cavity with torn edges appeared in the center. Courtesy of GEOKHI.
– This is true. But in laboratory conditions we could not otherwise obtain the maximum temperatures and pressures during an impact that can only occur in outer space. High-speed collisions between solid bodies in the Solar System generate pressures and temperatures exceeding 100 gigapascals and thousands of degrees Celsius.
– We cut this sphere in half and sawed off a thin layer of material (several millimeters) from one of the parts for study.
It turned out, firstly, that the meteorite reset its magnetic memory during its journey to us, – lost information about the magnetic fields of his parent body. This was due to the fact that its composition was initially magnetically soft.
Slip stripes discovered in Ching after an experiment on the earth's test site. Courtesy of GEOKHI.
The second conclusion turned out to be much more interesting. Before our study, the extent of the Chinge shock changes was unknown to anyone. It was difficult to understand this, since its composition is outwardly very homogeneous and does not have a clear structure in the form of grains, like other meteorites. We studied its shock metamorphism, which in natural material turned out to be quite moderate. But in a laboratory experiment, for the first time for an iron meteorite, we reproduced the so-called slip bands – an artificially obtained marker of an experienced conflict. These are defects in a material that occur when one layer of it shifts relative to another (a characteristic marker of impact changes in iron meteorites). There were no such bands in the Ching control sample. They appeared only in the sample we struck.
Before us, scientists observed slip bands only in natural samples of iron meteorites, but did not know at what pressure they were formed. In our work, we were able to record this pressure – it turned out to be above 30 gigapascals. The absence of such stripes in the natural specimen of Ching suggests that it did not experience impacts of such force in space.
The third result we obtained concerns the temperature estimate of the impact metamorphism of Chinge. Having examined its composition, we came to the conclusion that under natural conditions it did not heat above 550 degrees Celsius. This again only happened in our experiment.
– As part of a natural fragment, we discovered the mineral tetrataenite – an alloy of iron and nickel. This mineral becomes disordered and turns into taenite at 550 degrees Celsius. If the natural sample had been heated higher, tetrataenite could not have been there. It was in these conditions that the Chinge experimental sample found itself in Snezhinsk, – after the explosion in the center of the ball, where the temperature reached almost several thousand degrees Celsius, all tetrataenite turned into taenite.
Thus, we actually for the first time assessed the degree of impact metamorphism of Chinge, and also obtained artificially created slip bands for the first time in the structure of the iron meteorite, which will allow us in the future to better understand the conditions of formation and change of celestial bodies.