QUT researchers used experimental x-ray techniques at the Australian synchrotron to gain fundamental insight into how gypsum dehydrates under pressure and the processes that create earthquakes.
In the study published in the journal Nature Research Communication media, QUT Researchers Dr Christoph Schrank, Dr Oliver Gaede, from School of Earth and Atmospheric Sciencesand MSc graduate Katherine Gioseffi joined forces with the Australian synchrotron and colleagues at the University of New South Wales and the University of Warsaw to study how gypsum dehydrates much faster under pressure.
“Dehydration is a process in which minerals release water bound in their crystal lattices due to heating,” said Dr. Schrank.
“The rocky shell of our planet, the lithosphere, contains many rocks rich in hydrated minerals. The water produced by the dehydration of the lithosphere has a huge impact on geological processes such as the formation of volcanoes, ore deposits and earthquakes. “
In the study, the researchers used a single high-pressure cell with synchrotron transmission x-ray scattering that uses extremely bright x-rays to reveal how rock samples transform under high temperatures and pressures across the body. nanometer (one billionth of a meter). .
Australia’s ANSTO synchrotron in Melbourne is located in a building the size of a football stadium and is capable of using electrons to produce intense beams of light more than a million times brighter than the sun.
In the research center, electron beams pass through tunnels at a speed slightly slower than the speed of light in a circular orbit that is “synchronized” by the application of strong magnetic fields.
Mineral dehydration, also called calcination, is important in industrial processes. For centuries, people have dehydrated gypsum (CaSO4 · 2H2O) to create hemihydrate (CaSO4 · 0.5H2O), better known as plaster of Paris.
The construction industry produces approximately 100 billion kg of plaster of paris each year for products including cement and mortars, and it is used in medical scenarios for casts for immobilization of fractured bones.
There is also an ongoing scientific debate about the origins of large deposits of gypsum and hemihydrate on Mars.
In this study, researchers tested whether the rate at which gypsum rock dehydrates is influenced by small stress changes, such as pressure changes in the functioning of plate tectonics.
“To our surprise, we found that if we clamped our samples with a vice slightly tightened, the rocks lost their water twice as fast as without clamping,” said Dr Gaede.
“This discovery has important implications for geological processes. When tectonic plates collide along their boundaries, the tectonic stresses inside the plates slowly build up over time. “
Dr Schrank said the new research suggests that a small growth in tectonic stress may speed up the release of water into the plates and therefore promote earthquakes and the formation of new minerals.
The research results could help engineers design more energy-efficient calcination processes.