Decades-long scientific debate over the origins of the Silverpit Crater in the southern North Sea has been resolved.
A decades-long scientific debate over the origins of the Silverpit Crater in the southern North Sea has been resolved thanks to a new study.
New evidence published in Nature Communications confirms that the crater around 80 miles off the coast of Yorkshire was caused by an asteroid or comet impact. Dr Tom Dunkley Jones from the School of Geography, Earth and Environmental Sciences at the University of Birmingham has dated the impact age to between 43 and 46 million years ago.
Dr Dunkley Jones said: “Studying the fossil remains of microscopic plankton now preserved in sub-sea sediments at the same level as the crater has shown that this catastrophic event had happened in a narrow time window in the middle Eocene epoch.”
The team of researchers led by Dr Uisdean Nicholson from Heriot-Watt University in Edinburgh, funded by the Natural Environment Research Council (NERC), used seismic imaging, microscopic analysis of rock cuttings and numerical models to provide the strongest evidence yet that Silverpit is one of Earth’s rare impact craters.
Studying the fossil remains of microscopic plankton .... has shown that this catastrophic event had happened in a narrow time window in the middle Eocene epoch
The Silverpit Crater sits 700 metres below the seabed in the North Sea, around 80 miles off the coast of Yorkshire.
Since its discovery in 2002, the three-kilometre-wide crater, which is surrounded by a 20 km-wide zone of circular faults, has been at the centre of a heated debate among geologists.
Initial studies suggested it was an impact crater. The scientists who found it pointed to its central peak, circular shape and concentric faults, characteristics often associated with hypervelocity impacts.
However, alternative theories argued that the crater structure was caused by salt moving deep below the crater floor or the collapse of the seabed because of volcanic activity.
The new research team used newly available seismic imaging data and evidence from below the seabed to prove the impact theory.
Dr Uisdean Nicholson, a sedimentologist in Heriot-Watt University’s School of Energy, Geoscience, Infrastructure and Society, said: “New seismic imaging has given us an unprecedented look at the crater.
“Samples from an oil well in the area also revealed rare ‘shocked’ quartz and feldspar crystals at the same depth as the crater floor.
“We were exceptionally lucky to find these - a real ‘needle-in-a-haystack’ effort. These prove the impact crater hypothesis beyond doubt, because they have a fabric that can only be created by extreme shock pressures.”
Dr Nicholson said: “Our evidence shows that a 160-metre-wide asteroid hit the seabed at a low angle from the west.
“Within minutes, it created a 1.5-kilometre high curtain of rock and water that then collapsed into the sea, creating a tsunami over 100 metres high.”
Professor Gareth Collins from Imperial College London was at the Silverpit Crater debate in 2009 and also provided the numerical models for the new study.
Professor Collins said: “I always thought that the impact hypothesis was the simplest explanation and most consistent with the observations.
“It is very rewarding to have finally found the silver bullet. We can now get on with the exciting job of using the amazing new data to learn more about how impacts shape planets below the surface, which is really hard to do on other planets. ”
The research was funded by the Natural Environment Research Council (NERC), full project details are available online.
Birmingham Fellow
Tom is a micropalaeontologist specializing in the study of fossil coccolithophore algae.
