Seafloor spreading

Mid-Atlantic Ridge on the globe (Photo: Sina Löschke)

It wasn’t until the mid-1960s, around third years after Wegener’s death, that his ideas received recognition in science. Seismological investigations showed that the Earth merely has a thin solid crust that floats on a plastic mantle. Deep inside our planet there’s a very hot core. The Earth’s crust, which contains the continents and seafloor, is geologically divided into seven large and numerous small plates. The plates move, driven by the heat convection in the Earth’s mantle, at a speed of several millimetres to centimetres per year (plate tectonics).

So-called mid-oceanic ridges run through the oceans. In these zones magma rises from the Earth’s interior to the surface, cools down there and constantly forms new seafloor. At the same time the existing seafloor spreads (seafloor spreading) and presses the Earth’s surface, including the continents, apart. In so-called subduction zones old seafloor is, in turn, pressed down, melts and in this way becomes magma again. A region in which new seafloor continuously forms is, for instance, Gakkel Ridge in the Arctic. This is a submarine mountain range whose northern foothills extend from the northeast tip of Greenland to Laptev Sea in Siberia. At this point the Eurasian and the North American plate drift apart by a few millimetres every year.

Using the research icebreaker “POLARSTERN” scientists study this system of ridges and investigate the effects of the mechanisms involved in the spreading process: volcanism, Black Smokers and lava flow.