Mapping the Alps: Investigating How Deep Rocks Come to the Surface

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Earth and Environmental Sciences
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PhD student Jennifer Spalding is sitting at a lab bench in front of a computer and Professor David Schneider is standing to her right.
Tens of millions of years ago, the African and Eurasian tectonic plates collided, giving rise to the Alps – a mountain belt stretching across much of southern Europe and reaching heights in excess of 4 km. Tectonic collision pushed rocks to >75 km depths, and a short time later the rocks returned to the surface. In the Austrian Alps, large-scale stretching of the plates led to the formation of the Tauern Window, a window-like geological structure that exposes these once-deep rocks.

PhD candidate Jennifer Spalding and her supervisor Professor David Schneider partnered with GeoSphere Austria and the University of Vienna to map the northern part of the Tauern Window. This will allow them to identify the geological structures that were responsible for bringing deep rocks through the crust — the outer layer of the Earth — to the surface. With the partners, Jennifer conducted fieldwork in the Alps over two summers to map the complex network of faults and other subtle tectonic structures. She is also using low-temperature geochronology to track the timing and the rate at which these rocks returned to the surface and cooled. According to Prof. Schneider, “Most people think about geochronology with regard to the birthdate of the rock, but we are actually determining the thermal history of the rock.” Various isotopic methods are employed, including 40Ar/39Ar geochronology on mica minerals, and fission-track geochronology on apatite minerals.

This partnership is a key step towards understanding the pattern of deformation of the Earth’s tectonic plates. This research will lead to the improvement of exploration models of metallic ore deposits, which are required for finding critical metals for battery technology and alternative fuel sources for a greener environment. Another byproduct of this collaborative research is a better understanding of long-term climate change caused by uplift of the Alps. In Prof. Schneider’s words, “If you put a massive barrier – the Alps – in the jet stream, then you should expect the climate to start changing.”

Both Jennifer and Prof. Schneider recognize the significant contributions of their collaborators Dr. Benjamin Huet (GeoSphere Austria) and Dr. Bernhard Grasemann (University of Vienna) in the success of their project. Prof. Schneider emphasizes the importance of international partnerships as they provide contrasting and complementary perspectives which are useful, not only for training students, but also for discovery-based science.

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