About 66 million years ago, a fireball about 10 kilometers in diameter collided with Earth near what is now the Yucatan Peninsula. The crash led to the Chicxulub crater, over 180 kilometers long, and precipitated the extinction of numerous species, including dinosaurs. The impact also gave rise to a mountainous ring, a peculiar chain of elevations that only the great cosmic carambola are capable of originating . However, until now it had not been possible to recover samples that would allow us to know with certainty how they are formed or the depth at which they arise. The Chicxulub crater is the only known crater on Earth that has this type of ring, but it is located underground and can only be accessed by drilling the rock that covers it.
Well, an international team of scientists from different disciplines and institutions has managed to extract nuclei of pink granite from this structure for the first time. In fact, David Kring, a geologist at the Houston Planetary and Lunar Institute in Texas, who has participated in this initiative, says that the samples are much better than they had expected.
The project has been extremely complex and has taken almost a decade to plan . When everything was ready, the machines penetrated 1,335 meters through the seabed off the coast of the city of Progreso, in Mexico, between April and May 2016. When they were at 618 meters, the augers reached the first rocks of those elevations. The recovered granite contains large crystals, which, in the opinion of geologists, suggests that it was originally between 8 and 10 kilometers deep. The crash knocked it out of its place and placed it on top of other rocks, thus mixing those near the surface with material below them.
The investigation seems to rule out in this way one of the hypotheses that the experts had been considering. This assumed that, after one of these impacts, almost all of the pulverized rock remained in place. Instead, the samples suggest that the object that hit the Earth made a deep hole in the crust and that the rock flowed like a liquid and rose upwards . Then it fell and spread around, forming the aforementioned ring.
In an essay published in the journal Science , the scientists, who hope that their study will shed some light on how other large cosmic carambola have contributed to shaping other stars, such as Venus or the Moon, indicate that the collision increased. porosity in the crust. This helped create new underground habitats in which certain microorganisms that could survive without sunlight thrived.
Image: Donald E. Davis / NASA
