S-CH PERTURBATION

Stress and chemical perturbation around mineral inclusions

 Partecipanti

Mappa

 Word cloud

Esplora la "nuvola delle parole (Word Cloud) per avere un'idea di massima del progetto.

 Obiettivo del progetto (Objective)

'The proposed project provide a comprehensive study of the chemical response of a host grain on volumetric changes connected with phase transition of inclusions in ultra-high-pressure rocks. The main goal is to investigate the effects of stress induced diffusion in a solid of uniform composition by means of an integrated approach including combination of conventional petrology methods with material science analytical techniques and numerical approaches. Though the interplay between stress and diffusion has been described in material science, the chemical response on stress induced during the solid phase transition has not been studied in geo-materials so far. The proposed hierarchic structure of observations on a wide range of length scales, from the thin section scale down to the nanometer scale will thus give a new and profound insight into the interplay of the kinetic processes, which control the microstructure and chemical evolution during solid phase transformation. The detailed analysis of these small scale processes in ultra high pressure natural samples will also offer valuable data for modeling larger scale processes in Earth interior. Moreover, as the diffusional relaxation modifies elastic state of the material which affects the mechanical properties of the phase, explicit formulation of relaxation kinetics and mass transport for natural, complex chemical system on small scale will provide insights relevant to problems in material science, ceramic industry as well as to radioactive waste disposal programs.'

Introduzione (Teaser)

Geological processes ranging from microscopic to global shape the Earth's surface. EU-funded researchers attempted to answer the question: 'What can we learn about metamorphism through the study of minerals in mountain belts?'

Descrizione progetto (Article)

Most of what is seen on the surface of the Earth and at shallow depth is related in some way to tectonic plates. Where tectonic plates collide, material is forced upward to form mountains or one plate is subducted below the other, resulting in volcanic mountains. Volcanoes, earthquakes and mountain building are the most spectacular processes.

Geologists working on the 'Stress and chemical perturbation around mineral inclusions' (S-CH PERTURBATION) project focused on metamorphism, a process that is not directly observable. For this reason, they examined the products of metamorphic events: rock-forming minerals. Tectonic plates squeeze the rocks at their borders with such a force that the structure of rocks changes to yield new minerals.

Numerous factors determine the type of metamorphic rock that will result from a pre-existing rock. These include the chemical composition of the original rock and the temperature at which metamorphosis occurs. Project geologists analysed high-resolution observations revealing the microstructural features in metamorphic rocks and significant pressure variations maintained on microscale.

Metamorphism is obviously not a static process. However, before the S-CH PERTURBATION project, pressure variations were not considered in conventional approaches to petrographic observations. They proved a necessary parameter for correct description of the recrystallisation of the original rock-forming minerals and changes in the structure and texture of rocks.

As metamorphic processes have operated throughout Earth's history, they have affected most crustal rocks. These rocks become exposed at the surface by the uplift and erosion of overlying rocks during the later stages of mountain building. The findings of S-CH PERTURBATION at mountain belts should further our understanding of the deformation of Earth's crust, as this repeatedly occurred throughout its geological history.