Fossil meteorite a 'challenge'
2006-05-17 15:10
Johannesburg - A fossil meteorite has been discovered in the Kalahari Desert announced scientists from the University of the Witwatersrand (Wits) on Wednesday.
"We are excited about this discovery because it challenges the conventional wisdom about the nature of the meteorite impact process," said Wits School of Geosciences researcher, Professor Lew Ashwal.
The 25cm meteorite was found in a the 145 million-year-old Morokweng crater, 766m beneath the Kalahari Desert in North-West, he said.
A scientific research paper confirming the find was published in the international science journal Nature this week.
Chemical and mineral data confirmed the meteorite was a fragment of the original five-to-ten-kilometre asteroid that formed Morokweng's 70km-diameter crater at the Jurassic-Cretaceous boundary.
The boundary is home to the first complete fossil stony meteorites found in an impact melt.
Ashwal said the chemical composition of the latest find differed from that of previous discoveries: "This discovery is significant because it means the original asteroid made it through the atmosphere, 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."
The discovery could suggest that previous evolution models of the projectile during impact were incomplete, and it supported the assumption that the identity of a large impactor could be inferred, said Ashwal.
"There is also no doubt that the discovery will help us to better understand meteorite impacts," he said.
- SAPA