Viscous EffeCTs On Raman-based elasto-thermobarometry (VECTOR): a field, mechanical and diffusion study of mineral inclusions entrapped under a wide range of metamorphic conditions

• Applicant: Professor Dr. Evangelos Moulas, Ph.D.
• Subject Area: Mineralogy, Petrology and Geochemistry
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 524829125

Many geological processes in the interior of the Earth undergo at a slow rate and high pressures and temperatures. Experimental work carried out so far contributes significantly to our knowledge of parameters controlling physical, chemical and mechanical properties of rocks and minerals. Despite this, understanding the complexity of geological processes that take place over millions of years remains challenging. This is due to the slow rate as well as the high pressure and temperature at which these processes occur, making it difficult to reproduce in a laboratory. Despite the difficulties that arise when studying the processes taking place in the interior of the Earth, the application of the principles of thermodynamics makes it possible to describe and interpret the record of pressure and temperature changes preserved in metamorphic rocks. In recent years, a method of estimating the pressure and temperature conditions experienced by rocks during their history has also been developed on the basis of measurements made using the Raman spectroscope. The described method (elasto-thermobarometry) uses the residual pressure, which can be preserved in mineral inclusions entrapped in minerals behaving in an elastic manner. However, recent studies have shown that minerals which usually behave in an elastic manner may be affected by processes leading to weakening of their elastic properties and making them unable to maintain the residual pressure of inclusions. These processes, collectively termed as viscous creep, hinder the deciphering of the pressure and temperature conditions of the metamorphism. The aim of our project is to develop a novel method that will allow the quantification of the impact of viscous creep on the ability to maintain residual pressures in mineral inclusions. The influence of viscous creep on the ability to maintain the residual pressure by mineral inclusions entrapped in the host mineral has been recognized relatively recently. Therefore, there are no systematic studies describing this phenomenon in the available literature. In the course of the project, we are going to create a coherent database including field observations, analytical measurements and we will perform numerical modelling of the various mechanical and chemical processes responsible for the re-equilibration of rocks at the mineral scale. The integration of these data will make it possible to describe quantitatively the effects caused by viscous creep and to determine the pressure and temperature of a metamorphism using Raman thermobarometry.

• DFG Programme: Research Grants
• International Connection: Poland
• Cooperation Partner: Professor Jacek Szczepanski, Ph.D.