Quantifying Microstructural Evolution in Moving Magma

Abstract

Many of the grand challenges in volcanic and magmatic research are focused on understanding the dynamics of highly heterogeneous systems and the critical conditions that enable magmas to move or eruptions to initiate. From the formation and development of magma reservoirs, through propagation and arrest of magma, to the conditions in the conduit, gas escape, eruption dynamics, and beyond into the environmental impacts of that eruption, we are trying to define how processes occur, their rates and timings, and their causes and consequences. However, we are usually unable to observe the processes directly. Here we give a short synopsis of the new capabilities and highlight the potential insights that in situ observation can provide. We present the XRheo and Pele furnace experimental apparatus and analytical toolkit for the in situ X-ray tomography-based quantification of magmatic microstructural evolution during rheological testing. We present the first 3D data showing the evolving textural heterogeneity within a shearing magma, highlighting the dynamic changes to microstructure that occur from the initiation of shear, and the variability of the microstructural response to that shear as deformation progresses. The particular shear experiments highlighted here focus on the effect of shear on bubble coalescence with a view to shedding light on both magma transport and fragmentation processes. The XRheo system is intended to help us understand the microstructural controls on the complex and non-Newtonian evolution of magma rheology, and is therefore

An Extended Rheological Map of Pāhoehoe—‘A‘ā Transition

“…and further investigation using methods to track the textural evolution of samples during flow (Dobson et al, 2020) will help to delineate more clearly this threshold.…”

PyPore3D: An Open Source Software Tool for Imaging Data Processing and Analysis of Porous and Multiphase Media

“…An example is discussed by Voltolini et al [ 35 ]. The evaluation of changes in number, volume and shape of crystals and vesicles deepens our comprehension of their nucleation and growth from silicate melts (Kudrna Prašek et al, 2018 [ 36 ]; Arzilli et al, 2019 [ 37 ]; Dobson et al, 2020 [ 38 ]; LeGall et al, 2021 [ 39 ]).…”

High‐Speed 3D Imaging of Multiphase Systems: Applying SCAPE Microscopy to Analog Experiments in Volcanology and Earth Sciences

“…While this technique allows imaging of samples of any size (with a decrease in resolution with increasing size), it has a limited imaging rate, on the order of minutes per volume, limiting its ability to capture fast processes. High-speed processes such as bubble formation, growth, and motion can be imaged using higher power X-rays such as those generated in a synchrotron, which can achieve up to ∼20 volumes per second (vps) on mm-to-cm-sized samples (e.g., Dobson et al, 2016Dobson et al, , 2020. For instance, in application to volcanology, synchrotron X-ray tomography has been successfully applied to high temperature experiments with synthetic magmas and has improved the understanding of small-scale 4D phenomena (Dobson et al, 2016(Dobson et al, , 2020Pankhurst et al, 2014).…”

“…High-speed processes such as bubble formation, growth, and motion can be imaged using higher power X-rays such as those generated in a synchrotron, which can achieve up to ∼20 volumes per second (vps) on mm-to-cm-sized samples (e.g., Dobson et al, 2016Dobson et al, , 2020. For instance, in application to volcanology, synchrotron X-ray tomography has been successfully applied to high temperature experiments with synthetic magmas and has improved the understanding of small-scale 4D phenomena (Dobson et al, 2016(Dobson et al, , 2020Pankhurst et al, 2014). However, access to synchrotron facilities is often competitive and associated with technical challenges, limiting the number of experiments that can be achieved.…”