Meteor impact in the Barents Sea

Christina B. Claussen
Illustrations: IKU and SINTEF Graphic Centre

Armageddon, the earth's meeting with a giant meteor, has been Hollywood's latest terror scenario and big money earner. But the phenomenon is real. During the summer, geologists from IKU Petroleum Research drilled into the center of a gigantic meteor crater in the Barents Sea. The "hole" is 40km in diameter and is evidence that a giant from the asteroid belt entered the earth's atmosphere and struck right off Norway's northern coast.

The seismic registrations shows the form and size of the crater. The diameter is 40 km and precise situation is 73^O40´N, 20^O40´E.

The severe collision with a meteorite occurred about 150 million years ago and may have led to an extensive environmental catastrophe. Hollywood movies have certainly amply nourished our fantasies, but temperatures of around 10 000 degrees Celsius and flood waves which spread from Canada to Russia are hard to relate to. Mud, rock and materials from the sea floor were flung into the atmosphere in a violent inferno. When the enormous forces finally settled, it became cold and calm. Dust and particles created a carpet that blocked out the sunlight, and what followed is known as an atomic winter. The event had great effect on life on earth. Large parts of the organic life were affected. And the Mjølnir Crater was created.

Rare discovery

The discovery of the crater in the Barents Sea was a coincidence. Norway's sea area is systematically mapped, using seismic registration in a continuous search for potential oil and gas reservoirs. It was in this way that the enormous formation, north of Hammerfest, was noticed. In the beginning, geologists thought it was an ordinary salt formation or submarine volcano. But certain indications meant that Steinar Gudlauggson, from the Department of Geology at the University of Oslo, had suspicions that this could be a very rare case. Geologists from IKU and the University of Oslo then put their heads together. Could it be a parallel to the often-mentioned Chicxulub Crater in Mexico, by many scientists regarded as responsible for the final extinction of the dinosaurs?

A detailed and time-consuming project was implemented. IKU already operated in this very region and could loan a series of core samples from close to the crater to be analysed. After an extensive study of 400 000 quartz grains from the actual area, the work provided the answers. Some of the grains contained traces of shock deformation, a characteristic crackle in the species of rock that evidence that enormous forces had worked their way in. Traces of iridium were found, a rare element in the platina group that is far more common in objects from space than on the earth's surface. With two such clear indicators, the researchers could establish that they had found one of the world's seven marine meteor craters.

Geological gem

"If we take a look at the moon, all of the holes on the surface are craters of meteor impacts," says project leader Henning Dypvik of the University of Oslo. "That's actually how it is with the earth too, but rivers, mountains and vegetation gradually wipe out traces.

"The Mjølnir Crater is extremely well preserved because, to a large extent, the environment in the sea takes care of the layer of sedimentary rock on the sea floor. All the geological layers in and under a submarine meteor crater function as solid documentation on the earth's development over millions of years."

At the end of August, the crater was drilled by a team from IKU. The 121m long core sample is described within the subject as a "geological gem". The Mjølnir Crater is one of the few instances where both the crater and the displaced material were found and described. The crater and the sediment, therefore, carry unique information about the process and consequences of such an impact.

Researchers from the project team of University of Olso, Vitenskapsmuseet (NTNU) and IKU will continue to uncover the crater's inner most secrets and will hopefully be able to tell us how life on earth survived being hit by a meteor 2km wide at a speed of 30 000 km/per hour.

Contact at IKU: Atle Mørk
Tel.: +47 73 59 11 63
E-mail: Atle.Mork@iku.sintef.no

Gemini fakta

A meteor is a relatively large fragment from the asteroid belt. A meteor consists of minerals and metals and are different from comets which come from outer space and mainly consist of ice.

Meteorites fall on the earth daily. According to statistics, a meteorite 250m wide will hit earth creating a crater 5km wide about once every 10 000 years.

In all, man knows of 160 craters on the globe, but just seven of these are submarine.

The drilling of the Mjølnir Crater was supported by Norsk Hydro, the Norwegian Petroleum Directorate, Philips Petroleum Company (Norway), Saga Petroleum, Seateam and Statoil.