Huge meteorite did not play a part in demise of dinosaurs, study says

The meteorite that caused the 15-mile-wide Boltysh impact crater in central Ukraine did not play a part in the demise of the dinosaurs, a new study argues. 

A team of geologists led by the University of Glasgow applied dating techniques to samples of melted rock created during the fiery landing of the meteorite, in Ukraine’s Kivorohad Oblast region. 

Analysis narrowed down the precise age of the impact to just over 65 million years ago – ruling out the chance that it contributed to the extinction of the dinosaurs.  

It’s already well known that the dinosaurs were wiped out by the Chicxulub impact event – a plummeting asteroid or comet that slammed into a shallow sea in what is now the Gulf of Mexico around 66 million years ago. 

The collision released a huge dust and soot cloud that triggered global climate change, wiping out 75 per cent of all animal and plant species.  

Researchers from the universities of Glasgow, St Andrews, Leeds, and Aberdeen, contributed to the new research, which is published today in the journal Science Advances.  

According to the team, Boltysh was created during one of the ‘most volatile periods in Earth’s geological history’. 

Following the impact, the Boltysh impact crater filled over time with water and formed a lake, although today it is empty and surrounded by sedimentary rock. 

Previous analysis of samples from the Boltysh crater, undertaken decades ago, suggested that the meteorite may have struck the Earth between 2,000 and 5,000 years before the Chicxulub meteorite impact in Mexico’s Yucatán Peninsula.

The Chicxulub impact is widely believed to have caused the mass extinction event that made non-avian dinosaurs extinct, and the climate event that created the geological signature known as the Cretaceous–Paleogene boundary. 

However, questions still remained over whether the Boltysh impact might have occurred close enough in time to have had an effect on both.

According to 2017 research, Chicxulub and Boltysh were formed ‘at almost exactly the same time’. But the new study shows this is not true. 

To determine the date of the Boltysh impact more precisely than ever before, the researchers selected four samples from two rock cores taken from Boltysh.

The samples consisted of rocks generated during the impact event and lake sediments that accumulated over time after the crater was formed. 

They determined the age of the samples using the argon-argon dating facility run by Professor Darren Mark at the Scottish Universities Environmental Research Centre in East Kilbride.     

Argon-argon dating measures the radioactive decay of potassium to argon. The level of decay acts as a ‘rock clock’, which ticks down over geological time and allows researchers to determine when the rocks were created.

‘Thanks to the efforts of researchers around the world, argon-argon dating has become increasingly accurate over the last few years,’ said study author Dr Annemarie Pickersgill at the University of Glasgow. 

‘That gives us a much sharper lens to examine the details of events like the Boltysh impact, and be able to determine with much more confidence exactly when they happened.’ 

The new analysis suggests that, in fact, the impact that caused the Boltysh impact crater happened ‘very close to 65.39 million years ago’.

‘That puts it firmly after the Chicxulub impact and the formation of the Cretaceous-Paleogene boundary, evidence for which is found in geological records around the world,’ said Dr Pickersgill. 

It was 650,000 years after Chicxulub – not between 2,000 and 5,000 years before at all.

‘The results allow us to place the Boltysh impact more accurately in our timeline of what happened to the Earth in the period after this mass extinction event, and better understand our deep geological history,’ said Dr Pickersgill.

In the paper, the researchers draw links for the first time between their new dating of the Boltysh impact and evidence for a known ‘hyperthermal’ event found in the Earth’s sediment record.

This period of extreme global heating is something scientists call the lower C29N hyperthermal.

At that time in Earth’s history, volcanoes in India known as the Deccan Traps were releasing vast amounts of greenhouse gases into the atmosphere, accelerating a period of global climate change. 

Evidence of the Deccan Traps’ contribution to climate change has been found in sediment records around the world.

‘Paleoclimatology aims to help us understand and adapt to today’s changing climate by studying how our atmosphere responded to environmental stresses in the past,’ said Dr Pickersgill.

‘Being able to link the Boltysh lake sediments to the lower C29N hyperthermal is another piece of the jigsaw which will form a clearer picture of how our planet has responded to climate change in the past.’