Geoscientists back from expedition to Labrador Sea

Jul 22, 2009
Members of the geophysical working group deploy the streamer, the 3,000-meter-long hydrophone cable used to receive the seismic signals. Credit: Ronald Freibothe, Alfred Wegener Institute

Scientists from the Alfred Wegener Institute have researched the geology of the seabed in the Labrador Sea on board of the research vessel Maria S. Merian. They have studied the so-called Eirik Drift at the southern tip of Greenland, a structure of several hundred kilometres length formed like a ridge. They discovered a submarine mountain (seamount) at the south-western fringe of their area of investigation that indicates volcanic eruptions during the past few million years.

The Eirik Drift rises 2,500 m above the surrounding at the southern tip of Greenland. Sediments have been depositing there for the last ten million years, forming a ridge-like structure. These sediments are ablated by ocean currents in the Greenland Sea and deposited in the Labrador Sea. This is also known to be the case with sand displacements caused by ocean currents, for example on Sylt. Caused by changing climate - the transition from warmer times to our current climate - the current drifted and changed its strength. Additionally, icebergs transport rock material from Greenland onto the seabed. Glaciers planed it off the island, and on breaking apart into icebergs, deposited it all over the ocean. Caused by the constantly expanding and surface during the geological cycles of glacials and interglacials, this material finds its way into the Eirik Drift, too.

Therefore, the Eirik Drift is an archive for the activity of Greenland's western boundary current and the dynamics of ice cover. Climate changes and current shifts of the last ten million years can be examined here. First results show that the drift shifted strongly to the North and the West. This event took place about 5.6 million years ago. A sediment drift can be observed for the period prior to that, but velocity and path of the current changed strongly. Researchers will be able to further analyse these data by means of computer models in order to describe these changes in more detail.

This is the seismic profile through the Erik Drift. The deepest horizon to be observed is the magmatic basement. On top the sedimentary sequences have been deposited. The sediment drift comprises a wedge-like sediment body, which has been relocated from the east to the west and eastwards again. This is a result of a relocation of the generating current. Modifications in paths of oceanic currents can be attributed to climate changes. Credit: Gabriele Uenzelmann-Neben, Alfred Wegener Institute

The researchers discovered something unexpected during the seismic investigation using a recording cable of 3.000 m length: "Surprisingly, an unknown elevation appeared on the images of the subsurface in the western area of the Eirik Drift, which almost breaks through the sediments to the top of the seabed at two places", reports chief scientist Dr. Gabriele Uenzelmann-Neben from the Alfred Wegener Institute for Polar and Marine Research in the Helmholtz Association. "The sedimentary layers are disturbed", the geophysicist continues. This elevation at the seabed, called Mount Maria S. Merian by the researchers, is about 1.500 m high - approximately as high as the Feldberg in the Black Forest. The seamount was formed by volcanism which pushed sediments upwards. Even the youngest sediment packages are affected by this movement.

It can therefore be concluded that this is a young event have occurred during the last few million years. This result changes the picture of the geological development of the outer part of the Labrador Sea. So far it was assumed that the formation of the seafloor in the Labrador Sea (tectonic activity) ended about 45 million years ago. The discovery of the seamount indicates that the seabed at the exit of the Labrador Sea changed in more recent times. A distinct changing seabed has an enormous impact on the circulation paths of deepwater, which maintains ocean currents like the Gulf Stream.

The expedition of RV Maria S. Merian, operated by the Leitstelle Merian/Meteor of the University of Hamburg, began June 17th 2009 in Reykjavik where it also ended July 13th.

Source: Helmholtz Association of German Research Centres (news : web)

Explore further: Carbon injection initiative supported by new research

add to favorites email to friend print save as pdf

Related Stories

RV Polarstern on its way to East Siberian Sea

Aug 21, 2008

Bremerhaven, August 19th 2008. German research vessel Polarstern, operated by the Alfred Wegener Institute for Polar and Marine Research in the Helmholtz Association, transits the Northwest Passage for the ...

Research around the North Pole

Oct 20, 2008

The German research vessel Polarstern has returned today to Bremerhaven from the Arctic Sea. It has cruised as the first research vessel ever both the Northeast and the Northwest Passages and thereby circled ...

Iceberg Scour Affects Biodiversity

Jul 17, 2008

Antarctic worms, sea spiders, urchins and other marine creatures living in near-shore shallow habitats are regularly pounded by icebergs. New data suggests this environment along the Antarctic Peninsula is ...

The sea ice is getting thinner

Sep 13, 2007

Large areas of the Arctic sea-ice are only one metre thick this year, equating to an approximate 50 percent thinning as compared to the year 2001. These are the initial results from the latest Alfred-Wegener-Institute ...

Less ice in the Arctic Ocean 6000-7000 years ago

Oct 20, 2008

Recent mapping of a number of raised beach ridges on the north coast of Greenland suggests that the ice cover in the Arctic Ocean was greatly reduced some 6000-7000 years ago. The Arctic Ocean may have been periodically ice ...

Successful series of measurements in Arctic sea ice

Aug 11, 2008

The German Research Vessel Polarstern had to prove its ice breaking capabilities in Arctic waters to gain data on two series of long-term research measurements. After working in regions up to latitude 82° ...

Recommended for you

NASA HS3 instrument views two dimensions of clouds

15 hours ago

NASA's Cloud Physics Lidar (CPL) instrument, flying aboard an unmanned Global Hawk aircraft in this summer's Hurricane and Severe Storm Sentinel, or HS3, mission, is studying the changing profile of the atmosphere ...

Research drones launched into Hurricane Edouard

17 hours ago

U.S. government scientists are launching winged drones into Hurricane Edouard, hoping to collect data that could help forecasters understand what makes some storms strengthen into monsters while others fade away.

User comments : 0