In recent days, the news has spread through the media of what could be the first impact shock of a meteorite in Spain. Currently, there are none confirmed in our country and, in fact, in the whole world there are only about 200 craters cataloged as such. That would make the news very exciting if confirmed. However, it is important to note that at the moment cannot be assured that the terrain being analyzed in the Almeria province contain this impact. Does that make it less exciting? Of course not.
This type of research is very interesting for all that it entails. That of this group of scientists, coming from the University of Almería, the Astrobiology Center of Madrid, the University of Lund and the University of Copenhagenis promising for several reasons, including the presence of a form of quartz that originates at pressure and temperature conditions that only match two phenomena: the impact of a meteorite or that of a nuclear bomb.
For now, the results have only been presented in the Europlanet Science Congress (EPSC) 2022, held in Granada. They need to gather more data to be able to publish the finding and confirm that it is a impact crater. In short, there is still much to study and caution is essential. However, what that wait can hold is exciting.
A possible impact crater in Almería
The discovery that has just been presented at the congress is the result of 15 years of research. It has not been easy, since the supposed crater is buried in more modern sediments. A part has been exposed as a result of erosion, but logically that makes investigation difficult.
Even so, at this time, and based on the results of previous investigations, they have been able to find evidence that leads them to think that it is an impact crater. The geophysical survey is still underway, but they already have two indicators that are normally associated with the meteor impact. On the one hand, the presence of shocked quartz. These are those in which, when taking a thin layer of quartz and observing it under a microscope, a displacement is observed along the crystallographic planes that can only be generated by a large and sudden increase in temperature and pressure.
The temperature reached in a volcanic eruption It might be enough, but the pressure isn’t. Therefore, this natural phenomenon is ruled out when these features are observed in the rock. Now, by convention, for a crater to be considered the result of a meteorite impact, 20 of these shocked quartz grains must be found. This allows establishing a statistical test in which it is ruled out that there may really have been confusion in the analysis. As explained to hypertextual the main author of the research, Juan Antonio Sanchez Garridoat the moment they already have confirmed the presence of 6.
On the other hand, another geological structure that is normally associated with the impact of meteorites or nuclear bombs are the chipped cones. These scientists have also been able to observe these structures in their possible impact crater. However, being in a private quarry, they are having certain access problems to be able to continue studying that second clue.
What would the crater be like?
In the absence of being able to confirm that it really is the result of the impact of a meteorite, these scientists consider that the crater must have some 4 kilometers in diameter, although it would be surrounded by a larger structure, about 20 kilometers long, where the impact would cause the collapse of the sedimentary strata. As for the age, it could be about a few 8 million years.
Why should the data be taken with caution?
At the moment in Spain there is no confirmed impact crater, not even this one. But there have been other proposals in the past. One of them, in the town of Azuarain Zaragoza, made dozens of headlines in 1997. It was even claimed that it was the result of an asteroid. However, after a long period of controversy with experts in the field, it was ruled out that it was such a thing.
Precisely for this reason, and for other similar cases ruled out around the world, there are many requirements to accept an impact crater as such. And it is that, in reality, there are many phenomena that can generate confusion.
On the one hand, as explained to hypertextual the geologist and astrobiologist expert in meteorites Jesus Martinez-Friasgaps and other apparent shock effects can be generated by purely tectonic causes. Furthermore, regarding shocked quartz, he notes that sometimes “minerals are deformed on a small scale and micro-tectonic textures are formed that can lead to confusion”. Precisely for this reason, statistical studies must be carried out with a minimum amount of shocked quartz grains.
In short, although, in the words of Martínez-Frías, it is “an interesting and novel hypothesis”, we must take it with great caution.
What if it really was a meteorite?
“The meteorite is the origin of life and may be the end of life, the main source of carbon that we have on Earth could have come from meteorites and the presence of many highly coveted noble metals also comes from them.”
With these words, Sánchez Garrido emphasizes the importance that could have at the scientific leveli will confirm that what they have found in Almería is an impact crater. In addition, one of his companions in the investigation, Sebastian Sanchez Gomezadds that it could be highly relevant in order to increase the options of scientific tourism in this province. “The prospect of not having to go to Mars for a walk is nice.”
Now it remains to wait. What they have presented at the congress must be taken to a scientific journal and, once analyzed by their reviewers, published. If it meets the necessary requirements, we could speak of an impact crater, with all that this entails. Meanwhile, the authors of the investigation themselves have insisted hypertextual in the importance of speak in the conditional
That is the magic of science. Sometimes, it is difficult to reach those fascinating milestones that we imagine in our heads. But precisely because of how difficult it is to reach them, when they are finally fulfilled, talking about fascination falls short. Let’s wait to see if this is also the case.