Growth and dissolution
Photo: Sebastian Cionoiu
Spontaneous mineral growth and dissolution in the rock of the Earth’s crust, until now observed only by chance and never described or systematically studied, are the focus of a new research project at Heidelberg University. The aim of the project at the Institute of Earth Sciences is to reproduce conditions similar to natural rock rupture processes in a controlled laboratory environment. “The outcome of our experiments is unknown,” states Dr Sebastian Cionoiu, who heads up the project together with Prof. Dr Lucie Tajcmanova. “If we succeed, however, they could lead to important new information in earthquake and materials research.” The experimental work is being funded by the Volkswagen Foundation. For the 18-month preparation phase to investigate the project’s viability, funding in the amount of approx. 120,000 euros is available.
Prof. Tajcmanova’s working group is studying mineralogical and petrological processes that occur in the Earth’s interior. Of significant interest is the lithosphere – the layer that makes up the outermost one hundred or so kilometres of the Earth’s interior. With their project, entitled “Fluid-Mineral Interaction during Instantaneous De-/Compression in Rupture Processes” (FIND RUPTURE), the researchers hope to find out how the sudden compression and expansion of so-called supercritical fluids affect mineral dissolution and precipitation in rocks. Another interesting aspect is how these processes relate to seismic activity and whether similar effects are seen in other materials such as high-performance ceramics.
“We know that mineral processes releasing water play a significant role in plate boundary regions, also called subduction zones. The fluids are known to contribute to earthquake mechanics, but the effect of the decompressing fluid on the surrounding minerals at the moment of an occurring rupture is still unclear,” explains Dr Cionoiu. The researchers believe that mineral growth during this time window could play a key role in subsequent processes of deformation and rupture.
Underlying their innovative approach to studying these phenomena is a modified high-pressure experimental technique which – in contrast to conventional methods – induces instantaneous pressure jumps in the rock sample. By carrying out experiments based on this technique, the Heidelberg researchers are looking to identify starting points to test their theory. “Until now, scientists have assumed that such mineral growth processes in rock occur only very slowly,” states Prof. Tajcmanova. “If our pressure jump experiments are successful, we may need to alter our thinking in this regard and hence widen our understanding of the relevant processes behind the earthquake cycle.” At the same time, the geoscientists are hoping for new momentum to diversify the manufacturing techniques for especially robust materials.
FIND RUPTURE, whose work began in the autumn, is one of 18 projects awarded funding through the “Experiment!” call for proposals from the Volkswagen Foundation. With this initiative, the foundation is supporting explorative research projects in the natural, engineering, and life sciences devoted to fundamentally new or risky questions. Research projects and ideas receiving support are those whose outcome is uncertain and need viability testing.
