Growth and analysis of experimentally zoned crystals

Tuesday, 15 December 2020: 10:45
Alessandro Musu1, Luca Caricchi2, Diego Perugini3, Rosanna Corsaro4, Francesco P. Vetere3 and Maurizio Petrelli5, (1)University of Geneva, Geneva, Switzerland, (2)University of Geneve, Earth Sciences, Geneve, Switzerland, (3)University of Perugia, Department of Physics and Geology, Perugia, Italy, (4)Istituto Nazionale di Geofisica e Vulcanologia, Palermo, Italy, (5)University of Perugia, Perugia, Italy
Abstract:
Magma reservoirs are directly associated with volcanic activity and for the release of the magmatic fluids responsible for the development of ore deposits. Understanding the processes acting at inaccessible depths is of crucial importance to interpret monitoring signals and to estimate the potential of magmatic systems to be associated with strategic resources. Minerals are witnesses of the temporal evolution of the physico-chemical conditions within magma reservoir recording variations of intensive parameters as chemical signals.

We grow chemical zoned minerals at the Petro-Volcanology Research Group of the University of Perugia, using tephra from 2002-03 Mt. Etna eruption as starting material. The zonation in minerals is been forced inside a high-temperature furnace by oscillating the temperature under three different conditions: static conditions, using a controlled deformation gradient (concentric cylinder apparatus) and using a chaotic mixing regime (Chaotic Magma Mixing Device – CMMD).

We collect major and trace elements distribution maps on a large number of crystals using Electron Probe Micro Analyzer (EPMA) and Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS), respectively. The data will be analysed using a series of custom-built machine learning algorithms to disentangle patterns related to variations of the thermodynamic conditions of crystal growth from those produced by the competition between diffusion and growth. Backscattered Electron (BSE) images of the sample will be also analysed for Crystal Size Distribution (CSD) using a Radom Cut correction. The aim of this project is to provide experiments that will help deciphering the chemical signals recorded in magmatic minerals.

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