Mapping the Earth Below the Oceans
Some 55 million years ago the continental crust between Norway and Greenland had thinned to such an extent that it broke up. Since then Norway and Greenland have been drifting apart, and new oceanic crust have been created in between the continents. Large quantities of sediments have been collected in this constantly growing rift which today is known as the North Atlantic. This makes the area particularly interesting to the scientists in the marine geology and geophysics group at the University in Bergen.
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The research group has a special focus on so called passive continental margins that are created when continents drift apart. The scientists study among other things the structural and volcanic processes on such margins and collect samples of the sediments. Most of the activities are concentrated on the continental margin outside Norway, but the group also focuses on fjord environments, the development of margins in higher latitudes and conducts research in both the Arctic and Antarctic.
Some of the scientific data are provided through the petroleum industry. The scientists also gather data through research expeditions on the vessels “G.O. Sars” and “Håkon Mosby”. These data includes core samples of sediments and seismic information. The core samples are analyzed to determine the age, chemical composition and origin of the depositions. The samples are also used to study slides and tsunami events. The most studied underwater slide on the Norwegian continental margin is the Storegga Slide that caused a large tsunami some 8200 years ago. Knowledge about this slide was of great importance to the petroleum industry prior to the development of the Ormen Lange gas field which is located just below the area of the slide.
Core samples need to be correlated to results from other methods in order to provide a larger picture. The marine geology and geophysics group conducts seismic analysis to map the earth crust and the sediments deposited in the ocean areas that are studied. Using an air gun – a low frequency echo sounding device - the researchers collect seismic profiles. These profiles provide a three dimensional picture of the geometry of the sediments. Another purpose of the seismic profiles is to help understand how the continental crust is thinned through the ages. Research has shown that the creation of this type of oceanic crust is more complicated than what has been hitherto assumed, with altering periods of volcanic activity and continental extension. Volcanism along the outer rims of the Norwegian continental margin has had an important influence on the maturation of hydrocarbons such as oil and gas, making research on this field highly valued to petroleum exploration.