An international team of researchers believes they have located in the Alhabia-Tabernas basin (Almería) what appears to be the first impact crater discovered in Spain. It measures about 4 km in diameter and may have been created by a meteorite that crashed into Earth 8 million years ago. The finding was presented at the Europlanet Science Congress (EPSC) 2022, held last week in Granada. Coincidentally, a few days later, NASA carried out its first planetary defense test in space by impacting a spacecraft, DART, against the Dimorphos asteroid to find out how to prevent a large rock from falling on us in the future.
Although around 200 impact structures have been identified worldwide, no signs of them have ever been found on the Iberian Peninsula. ‘We have investigated numerous aspects of the region’s geology, mineralogy, geochemistry and geomorphology. The Alhabia and Tabernas basins in the area are filled with sediments dating between 5 and 23 million years, and overlying older metamorphic rocks,” explains Juan Antonio Sánchez Garrido, from the University of Almería.
“A large part of the impact structure is buried by more modern sediments, but erosion has exposed it and has opened the opportunity for studies,” explains Juan Antonio Sánchez Garrido, from the University of Almería. The crater itself is believed to be about 4 kilometers in diameter and buried at a depth of 1,000m. The edge of the structure reaches a diameter of 20 kilometers, where the impact caused the collapse of the sedimentary strata.
deformed by pressure
Evidence from the crater includes several examples of “shocked” quartz grains in breccias, a type of sedimentary rock with large fragments cemented in a finer-grained matrix. The grains show signs of deformation from the enormous impact pressures, which ranged from 10 to 30 gigapascals.
“If the discovery of the crater is confirmed, it would not only be exciting from a scientific perspective, but it would also be a wonderful addition to the scientific and tourist attractions of the province of Almería,” says Professor Sánchez Garrido.
The largest impact crater on Earth is the Vredefort crater in South Africa. It has a diameter of 160 kilometers and was caused 2,023 million years ago by an asteroid between 5 and 10 kilometers in diameter. The brutal blow caused an energy release of 100 million megatons. It is followed in size by Chicxulub, in the Yucatan peninsula. With a diameter of 150 kilometers, it was created 66 million years ago by the meteorite that killed the dinosaurs.