Deep Impact

Scientists now understand the importance of large asteroid impacts on the Earth and other planets in the solar system.  Not only are asteroid impacts implicated in mass extinctions, they form traps for oil and gas, and in the early history of the Earth and Mars, they may have been important habitats for life.

In the last 25 years, scientists have come to understand the potential importance of asteroid impacts on the Earth and other planets in the solar system.  They are implicated in mass extinctions, in the formation of traps for oil and gas, and in the early history of the Earth and Mars they may have been important habitats for life.  This project, which  involves Open University CEPSAR scientists Simon Kelley, Iain Gilmour, Jon Watson, and David Jolley  of the University of Aberdeen, launched in 2006 to investigate in detail the Boltysh meteorite impact crater in the Ukraine.

The crater was formed in a very shallow sea on a flat continental shelf sixty five million years ago, at the same time as the Chicxulub crater in Mexico, though it has not been possible to determine whether the two happened at exactly the same time.  After the impact, the crater was quickly filled with a freshwater lake. Over the next fifteen million years the lake filled with fine sediment and the organic remains of the flora and fauna which lived in the lake, or were washed in by rivers.  The fact that Boltysh remained a hole in the ground on the flat continental shelf means that it holds a unique and near continuous record of the Cretaceous-Tertiary (KT) boundary (between the age of dinosaurs and the age of mammals) and early Paleogene period.  This project has drilled two holes and recovered cored sediments from the crater floor up to the point when the sea invaded the crater around 50 million years ago. These samples arrived for analysis in October 2008.

What can we learn from these sediments?

First, the team should be able to establish the age of the crater more precisely, and perhaps whether it formed at the KT boundary, predates or indeed post-dates it.  The team’s previous work shows that the crater formed within about half a million years of the boundary, but at least one crater of this size (24 km diameter) forms on Earth every 1 million years so it might be coincidence.  If it did form at the same time, it would be convincing evidence that several meteorites fell at the KT boundary, and this could change ideas about what happened at the end of the Cretaceous period. Even if the two impacts were not simultaneous, the team will be able to use signals in the sediments to constrain the KT events.

Second, sediments deposited soon after impact will tell the team how long the crater lake remained hot.  This will be an important result because impact craters may have provided an important habitat for life on the early Mars and also possibly on Earth.  There were more impacts when the planets were young and warm crater lakes may have been places where early forms of life could survive.  A similar study being undertaken in a crater in Africa (Bosumtwi in Ghana) will be combined with this work to model crater lakes on early Earth and Mars.

Early life is also related to the team’s final aim, which is to use pollen, spores and algae preserved in the sediments to uncover evidence about the processes of devastation and biotic recovery after a significant meteorite impact event.  Studying the Boltysh crater will allow us to produce a detailed model for ecosystem recovery following the impact event.

Latest news on the project can be found here:  http://www.open.ac.uk/science/pssri/about-the-department/news/news.php?article_id=14660

For further information contact: Dr Iain Gilmour

Back to top