Better insights into the Earth’s interior

LMU geophysicist Max Moorkamp has developed a method that allows us to study the composition of the Earth with better results.

Knowledge of the structure and composition of the Earth’s crust is important for understanding the dynamics of the Earth. For example, the presence or absence of melting or fluids plays a major role in plate tectonic processes. Most of our knowledge in this area comes from geophysical surveys. However, the relationship between measurable geophysical parameters and actual conditions inside the Earth is often ambiguous. To improve on this, LMU geophysicist Max Moorkamp has developed a new method of combining and processing data on the distribution of electrical conductivity and density in the Earth’s crust using a method derived from medical imaging. “The advantage is that the relationships between the two parameters are part of the analysis,” says Moorkamp. “For geophysical applications, this is completely new.”

Using the new method, Moorkamp was able to show that previous assumptions about the spatial distribution of magma and fluids in the western United States may be oversimplified. Based on electrical conductivity measurements, researchers had previously assumed that molten rock (magma) and fluids are prevalent in geologically young and active regions, while older, stable regions are virtually free of fluids. “However, the new results show a more complicated picture,” says Moorkamp. The electrical conductivity of molten rock and fluids is very similar to that of solid graphite and sulphides – unlike melts and fluids, however, these are a sign of ancient geologic activity.

Using his method, Moorkamp was able to distinguish between the two for the first time and thus demonstrate that even in the highly active region around Yellowstone there are fluid-dominated structures directly adjacent to fluid-free zones with graphite and sulphides. From these findings, the geophysicist concludes that compared to current geologic activity, geologic history – that is, past plate tectonic processes – has a much greater influence on the location of fluids. than previously assumed. This may require a revision of past results not just in the United States but around the world. Moreover, the technique could be very useful in the search for geothermal energy or mineral deposits.

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Betty K. Park