Department 4: Geomaterials

For many decades we have known that neither the interior nor the surface of the Earth behave as rigid and immobile bodies. However, many details of the dynamic behavior and interactions between the lithosphere and mantle remain a mystery. This lack of understanding has several causes. We cannot directly observe the deep interior of the Earth; these movements proceed so slowly that the span of a human life is often too short to measure any of the changes; and, finally, the chemical processes are extremely complex, especially at the Earth's surface. In Department 4, our goal is to investigate this aspect of the dynamics of our planet in detail.

To investigate these processes and interactions, we survey tectonically active regions in close collaboration with other GFZ departments. In these regions, we combine geological field studies with the geophysical measurements of independently and automatically operating Plate Boundary Observatories. These instruments measure the drift and deformation of the lithospheric plates in detail. Alone, such field measurements are not enough to understand the processes behind the movements. Using selected rock samples, we investigate in our laboratories how they deform under pressure and under which conditions they break. Thus, we replicate on a small scale what happens during an earthquake in nature. With diamond anvil chambers and other tools, we simulate the high temperatures and pressures in the Earth's lower crust and mantle. In this way, we experimentally verify how rocks really behave in the Earth’s interior.

Even the causes for rapid, measurable changes which take place at the Earth's surface are veiled in mystery. Throughout the world, every year enormous quantities of sediment are delivered from the mountains to the seas by rivers and glaciers. At the Earth's surface, where this material is eroded, so many forces are at work simultaneously that we often cannot decipher how these complex processes interact. These processes range from wind and weather, to the weathering of rocks through soil bacteria. With chemical methods, we measure the speed at which the surface processes act and search for the geochemical fingerprints which act as clues to understanding what causes these processes and how they interact.