[LUM#6] At the heart of the crater

[LUM Magazine] - Published on July 3, 2017 in Science and Society

How was the giant Chicxulub crater formed by an asteroid impact 66 million years ago—an event believed to have likely caused the extinction of the dinosaurs? That is the focus of an expedition in which Johanna Lofi, a geophysicist at Géosciences Montpellier, participated.

This was the most recent global catastrophe. Some 66 million years ago, a giant asteroid struck the Earth, causing the extinction of most Cretaceous species and likely bringing an end to the reign of the dinosaurs. The Chicxulub impact crater formed in a matter of minutes, reaching 180 km in diameter. 

For the first time, an international team of researchers has drilled into the central rim of this crater, which is now buried under 600 meters of sediment in the Gulf of Mexico. Scientists and drillers spent two months at sea in 2016 (as part of the scientific drilling programs International Ocean Discovery Program and International Continental Drilling Program), drilling day and night through the famous central ring to extract rock samples… down to 1.3 km below the seafloor.

 “Of the three largest craters on Earth, this is the only one associated with a mass extinction, ”explains Johanna Lofi, a geophysicist at the Montpellier Geosciences Laboratory who took part in the expedition. “It is also the only one whose central ring has been preserved by the marine sediments that covered it.” The study of the samples will provide a better understanding of how giant craters form and allow for a detailed reconstruction of the history of this asteroid impact and the mass extinction that followed. The initial results were published in the journal Science in 2016 (The formation of peak rings in large impact craters).

Keywords: Geosciences, LUM#6, LUM Magazine, Research, Science