Until now, the likelihood of the Martian origin of the Tunguska meteorite has been swept away due to the presence of quartz in its alleged fragments. The new study highlights that traces of quartz have been found on Mars in recent years.
When in the spring of last year, Andrei Zlobin, then working at the State Geological Museum. V. I. Vernadsky of the Russian Academy of Sciences, said that he had found three fragments of the Tunguska meteorite, this caused … rather sharp criticism - both here and abroad. Vitreous crust, which is not found on meteorites; the fact that all three stones were found on the surface, close to the riverbed and without any stratigraphic reference; Finally, in the 25 years that have elapsed between the discovery and the appearance of the preprint of Mr. Zlobin on arXiv, no one bothered to conduct a chemical analysis of the stones - all this, as they say, was a little embarrassing. Among other things, the Zlobin samples contained quartz - to put it mildly, a very rare occurrence for meteorites known today.
Until the recent Chelyabinsk event, many tended to the cometary version due to the absence of an impact crater and meteorite debris under Tunguska. After it became clear that an impact crater and a sea of debris in such cases are not at all necessary, the supporters of the Tunguska meteorite version revived. (Photo by Wikimedia Commons.)
Now Yana Anfinogenova, representing Tomsk State University, together with her colleagues tried to find an approach to the so-called John's stone - a strange fragment found in 1972, precisely in terms of its chemical composition. At the same time, scientists noted the similarity of its composition with the wreckage examined by Andrei Zlobin.
As a result, the authors of the new study come to the following conclusion: the stone - mostly sandstone with a grain size of about 0.5-1.5 cm - is structurally similar to those found on Mars, including in recent years. The presence of quartz, although at odds with the data characteristic of known Martian meteorites, is quite compatible with the data of the rovers, which showed that there are traces of quartz on this planet.
This is a rather strong and not put forward by the same Andrei Zlobin argument, which somewhat levels out earlier criticism of his work. We will remind, last year Natalia Artemyeva from the Institute of Dynamics of Geospheres of the Russian Academy of Sciences said that on meteorites "there is no glassy crust, they do not contain quartz, as Zlobin says." Obviously, the lack of reliable information about the presence of quartz in meteorites of Martian origin does not in any way negate the fact that if there is quartz on Mars itself, then sooner or later it may also be included in the local meteorites falling to the Earth.
However, in the work of Ms. Anfinogenova and her colleagues, alas, there is no attempt to investigate the "John's stone" by analyzing the isotopic composition of its inclusions. But this could just greatly advance the matter: the isotopic composition of the gas inclusions of the meteorite would give an atypical ratio of argon isotopes, because in the Martian atmosphere, due to low gravity, its light isotopes are almost absent (unlike on the earth), and for solid rocks the situation is could have cleared up considerably.
Map of locations searched for wreckage (illustration by Yana Anfinogenova et al.)
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Already now, with a significant degree of probability, it can be argued that the work will cause sharp criticism: among other things, many meteorites of clearly Martian origin are known on Earth, but among them, in fact, there are no such, the composition of which would coincide with the described composition of the supposedly Martian “stone John."
Obviously, this is a problem for the hypothesis, but not completely unsolvable: three quarters of the Martian origin of meteorites consists of rocks, which, on the contrary, can hardly be found on Mars - relatively young (much younger than the known parts of the Martian surface), and, given the small the fourth planet, it is completely unclear where to take on it such a site that would be covered with young rocks and at the same time would remain completely unexplored by terrestrial vehicles. In a word, recalling the so-called Shergotite problem, it is difficult to reject the likelihood of a truly Martian origin of the debris found in the area of the fall of the Tunguska meteorite …