The Yermak Plateau forms the northernmost plateau of the Eurasian plate. It is believedto be formed as a consequence of relative motions between Greenland andSvalbard. Large parts of the plateau might consist of heavily intruded continental crustand/or are of oceanic origin. The intruded material are most likely erupted during thefinal formation of the western Gakkel Ridge some 35 Ma. As a consequence of thecontinuous separation of Greenland and Svalbard an active spreading system, the LenaTrough, in the Fram Strait developed.This general scenario is well accepted, but details on the crustal structure, sedimentdistribution and basement origin of the Yermak Plateau and the Lena Troughare unknown. Recent bathymetric, petrological and geophysical investigations haveincreased the first order information for this region significantly. E.g. the newbathymetry shows that in contrary to older models, no complex geometry of thespreading system is present. The Lena Trough system is only to a minor amount disruptedby transforms.The problem in detailed dating the spreading history of the Lena Trough, and in reversethe opening of the Fram Strait is the absence of good spreading anomalies. Newaeromagnetic data confirm this observation from regional surveys. The magnetic fieldis extremely smooth south of 82°N. However, linking this information with the latestresults from RV Polarstern expeditions in 2004 explains at least these observations. Itseems that most of the oceanic crust in the Lena Trough is build up by peridotites.In addition to the investigation across the Lena Trough new seismic data were acquiredin 2004 across the Yermak Plateau to map the shape of the basement. The seismicdata show that the basement is very rough in the oceanic part of the plateau, and thattowards the east a major tectonic boundary exists. This boundary is visible also in thegravity and to minor amount in the magnetic data. The seismic data suggest that thisboundary might represent an area of different stress directions.In summary the latest results of the geoscientific investigations in this area will bepresented.
Helmholtz Research Programs > MARCOPOLI (2004-2008) > MAR2-Palaeo Climate Mechanisms and Variability