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Scientists discover the first impact crater in Spain

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The impact crater, which was caused by an impact about 8 million years ago, is about 4 kilometers (2.5 miles) in diameter.

The crater was found in the province of Almeria.

The first probable impact crater in Spain has been discovered in the southern province of Almeria. The discovery was recently reported by Juan Antonio Sánchez Garrido of the University of Almeria at the Europlanet Scientific Congress (EPSC) 2022.

Although there are over 200 known impact structures, this study is the first to find evidence of an impact crater on the Iberian Peninsula. The discovery is the product of 15 years of research carried out by an international team of scientists from the University of Almeria, the Center for Astrobiology in Madrid, the University of Lund and the University of Copenhagen.

Alhabia Tabernas basin crater

Location of the center of the crater and radius of 20 kilometers from the area affected by the impact in the Alhabia-Tabernas basin. Credit: Sánchez-Garrido et al 2022. Basemap: Instituto Geográfico Nacional (IGN)

Professor Sánchez Garrido said: “We believe the impact event occurred around 8 million years ago. We have studied many aspects of the geology, mineralogy, geochemistry and geomorphology of the area. The Alhabia and Tabernas basins in the region are filled with sediments from 5 to 23 million years old and overlie older metamorphic rocks. Much of the impact structure is buried by more modern sediments, but erosion has exposed it and opened up the possibility of study.

The crater itself is estimated to be 4 kilometers (2.5 miles) in diameter, surrounded by a larger structure 20 kilometers (12.4 miles) in diameter, where the impact caused the sedimentary layers to collapse .

Impact Crater Spain Infographic

Much of the impact structure is buried by the most recent sediments. The crater itself is 4 kilometers in diameter and is buried at a depth of 1000 m. The edge of the structure reaches a diameter of 20 kilometers. Credit: Sánchez-Garrido et al 2022

Evidence from the impact crater includes several examples of “shocked” quartz grains in the breccia – a type of sedimentary rock with large fragments cemented into a finer-grained matrix. The grains show signs of deformation under the enormous pressures of the impact, which were between 10 and 30 gigapascals.

“If the discovery of the crater is confirmed, it would not only be exciting from a scientific point of view, but it would also be a wonderful addition to the scientific and tourist attractions of the province of Almeria,” said Professor Sánchez Garrido.

Evidence of the Spanish impact crater

Evidence from the impact crater includes several examples of “shocked” quartz grains in the breccia – a type of sedimentary rock with large fragments cemented into a finer-grained matrix. The grains show signs of deformation under the enormous pressures of the impact, which were between 10 and 30 gigapascals. Credit: Sánchez-Garrido et al 2022

EPSC2022, which took place last week in Granada, brought together nearly 1,200 planetary scientists from around the world, making it one of the largest planetary science meetings to take place in Europe.

Thin sections showing deformations in three grains of quartz

Thin sections showing deformations of three quartz grains, produced by shock effects, in an impact breccia at Tabernas. Credit: Sánchez-Garrido et al 2022

The president of the local organizing committee, Luisa Lara of the Instituto de Astrofisica de Andalucía-CSIC, said: “It was a lot of work to prepare for the meeting and we had to wait two years because of the pandemic. But the thrill of welcoming everyone to EPSC2022 in Granada has paid off – all the hard work is forgotten and the success of the meeting is a wonderful reward.

Reference: “A probable impact structure in Betic Cordillera, Almeria, SE Spain” by Juan Antonio Sánchez Garrido, Jens Olof Ormö, Carl Alwmark, Sanna Alwmark, Gabriel Zachen, Robert Lilljequist and Sebastián Tomás Sánchez Gómez, September 23, 2022, Europlanet Scientific Congress 2022.
DOI: 10.5194/epsc2022-217