The DanSeis Centre at the University of Copenhagen has just received a grant of more than €3 million from the Danish Ministry of Science, Innovation and Higher Education to investigate and tackle one of geoscience's great mysteries: do mantle plumes, hypothetically buoyant regions of heated mantle material rising towards the earth's surface, actually exist?
"It is believed that there are roughly 30 mantle plumes scattered about the planet. From them, heated mantle material rises from the Earth's liquid core, into the lithosphere and towards the crust. Some of the most impressive plumes are presumed to be located beneath Iceland, Hawaii and Yellowstone National Park in the US state of Wyoming - all areas with significant volcanic activity and hot spots. Until now, the sciences have been unable to prove their existence. With the DanSeis Centre and its research staff, we will be equipped to provide new data and settle the question," says Professor Hans Thybo of the University of Copenhagen's Department of Geography and Geology (ICG). The Department is behind the DanSeis national instrument centre.
Hundreds of kilometers within the Earth
To solve the mantle plume mystery, Hans Thybo and colleagues will lower advanced seismographic equipment onto the Atlantic seabed in a 1000 km radius surrounding Iceland - well into the zone of Greenland's bedrock and around the Faroe Islands.
"Using new methods and instruments, we can take geologic measurements much deeper within the Earth than before. Now, down to 500 and 1000 kilometers! Methods in current use, by the oil industry among others, provide information for areas down to between 6 and 10 kilometers," explains Professor Thybo.
The mantle plume mystery
Determining the existence of mantle plumes has been a fundamental question since the development of plate tectonics in the 1960's and 70's. Plate tectonics is a geophysics-geologic theory built upon the premise that Earth's exterior is divided into plates which shift in relation to one another. Science, the world's leading scientific journal, regards the mantle plume mystery as the today's most important geoscientific question. Are mantle plumes a means of transporting heat from the Earth's core to its surface? Or, is heat from the center of the Earth diffused more evenly throughout the planet's oceans and continents?
Future oil exploration
Professor Hans Thybo has previously attracted international attention with his examination of Lake Baikal, the planet's deepest lake, found in Siberia. At the time, tons of dynamite were bored underground and set off at a depth of 70 metres to investigate the unique Baikal Rift Zone, upon which the 1700 metre deep Lake Bailkal is saddled. Rift Zones are elongated geologic depressions, also known as crustal fractures. They can plunge up to ten kilometres into the Earth's crust and contribute to the fracturing of tectonic plates upon which continents rest.
"The Baikal project allowed us to follow sound waves, produced by explosions, into the Earth's interior. The same method will be deployed up in Iceland. Using the recordings of earthquake waves and so called 'air canons' loaded with compressed air, we will be able to examine the composition of rock deep within the Earth," explains Thybo, who adds that the technique might also be adapted for oil exploration.
Terrestrial conditions below a depth of 50 kilometres will be investigated by recording the shock waves of distant earthquakes. This monitoring requires that the instruments be stationed on the Atlantic seabed for two years. Beyond their work shedding a vigorous and much anticipated new light upon the mantle plume mystery, DanSeis will also address other basic research challenges, such as investigating the origin of mountains found in the North Atlantic area - Norway and Greenland included.
DanSeis has been awarded €3.35 million by the Danish Ministry of Science, Innovation and Higher Education. DanSeis is headquartered at the University of Copenhagen's Department of Geography and Geology and will begin operations from Spring 2012.
Professor Hans Thybo
Department of Geography and Geology