Australian National University archaeologist Andrew Glikson said seismic activity led experts to the Mount Ashmore 1B site, and a study of fragments showed a large meteorite hit just before the Earth’s temperatures plunged.
“The identification of microstructural and chemical features in drill fragments taken from the Mount Ashmore drill hole revealed evidence of a significant impact,” Glikson said, adding it was at least 50 kilometres (31 miles) wide and about 35 million years old.
A meteorite 100 kilometres wide hit Siberia at the same time, along with an 85 km one in Chesapeake Bay, off the US coast of Virginia, followed by a large field of molten rock fragments over northeast America, he said.
“This defined a major impact cluster across the planet,” said Glikson.
Glikson said the findings, published in the latest issue of the Australian Journal of Earth Sciences, could suggest a link between the impacts and a sharp fall in global temperatures which preceded the formation of the Antarctic ice sheet.