Clay minerals, which are a key component of the Earth’s surface, primarily exist in the sediments found in lakes, rivers, and oceans. The characteristics of clay and claystone are significantly influenced by the arrangement of their tiny sediment particles. A research team has recently achieved a groundbreaking observation of these processes.
Clay minerals are a key component of the Earth’s surface, primarily located in the sediments of lakes, rivers, and oceans. The features of clay and claystone are largely affected by the orientation of their minute sediment particles. Utilizing the advanced European Synchrotron particle accelerator in Grenoble, France, a research group from Martin Luther University Halle-Wittenberg (MLU) has for the first time closely examined how these processes function. Their findings were published in the journal Communications Earth & Environment, offering valuable insights into sediment structure and properties.
Studying the creation of clay-rich sediments poses challenges. “Sedimentation happens, for instance, on the challenging-to-access ocean floor over extended time periods. Moreover, clay particles are minute, measuring only a few micrometers or less. Commercial microscopy techniques are inadequate for observing these clay particles during sedimentation,” explains Dr. Rebecca Kühn, a geoscientist at MLU and the lead researcher of this study. To tackle these issues, the research team employed cutting-edge technology; the Synchrotron particle accelerator in Grenoble. “This device enabled us to watch sedimentation as it occurred,” states geologist Professor Michael Stipp from MLU. The researchers placed cylinders filled with water containing sinking clay particles into the high-energy x-ray beam from the accelerator, conducting experiments under various conditions such as fresh and saltwater. They measured the particles’ alignment over time for each scenario. Such measurements can yield vast amounts of data, but due to the lack of a rapid evaluation method, co-author Dr. Rüdiger Kilian from MLU developed one specifically for this new research.
Results indicated that clay particles begin to align within the first few millimeters of sediment. “The particles attain a certain orientation quite early, specifically at the interface between water and sediment. This alignment intensifies within the first few millimeters of sediment,” Kühn states. “This finding is unexpected because a common belief was that the alignment of clay particles is mainly influenced by the thick layers of sediment above, often meters deep,” remarks Stipp. The data from the Halle research group challenges or at least broadens this prevailing assumption.
Gaining insight into clay particle alignment is vital for various applications. “This alignment affects the diffusion and thermal characteristics of clays and claystones, which are critical for geothermal energy and for rock formations that host nuclear waste repositories,” Kühn adds.
