Wits scientists discover meteorite
A 25cm fossil meteorite has been discovered in the 145-million-year-old Morokweng crater, about 766m beneath the Kalahari Desert in the north-west province of South Africa, the University of the Witwatersrand announced on Wednesday.
Morokweng, formed by an asteroid at the Jurassic-Cretaceous boundary, is a crater about 70km in diameter and is home to the first complete fossil stony meteorites found in an impact melt. Large craters are formed when massive objects pass through the atmosphere with a minimal reduction in velocity.
Chemical and mineral data confirm that the meteorite boulder is a fragment of the original asteroid that first struck Marokweng. The chemical composition of this meteorite also differs from that of previous discoveries.
“This discovery is significant because it means that the original asteroid made it through the atmosphere and impacted with the surface of the Earth and survived the intense heat it created.
In most cases, meteorites simply vaporise when they reach the atmosphere,” says Professor Lew Ashwal, a researcher of the project, from the School of Geosciences at Wits University.
According to Ashwal, there are several major implications of this discovery.
“Firstly, it could suggest that previous models for the evolution of the projectile during impact are incomplete. Secondly, it supports the assumption that the identity of a large impactor can be inferred,” says Ashwal. “There is also no doubt that the discovery will help us to better understand meteorite impacts.”
Three Wits researchers, including Wits’ Dr Marco Andreoli, formed part of the international research group.
“We are excited about this discovery because it challenges the conventional wisdom about the nature of the meteorite impact process,” the researchers said. - I-Net Bridge