Skip to main content
John Wheeler

Professor John Wheeler
Ph.D.

Research

I have a varied research interests and expertise involving field and microstructural studies, analysis and modelling of microstructural and chemical data, and collaborating with experimentalists, all to better understand physical and chemical processes in the Earth. In the last ten years my research has focussed on three themes (more information here).

- Electron Backscatter Diffraction
Crystal orientation data allow the investigation of many geoscience problems. We can now gather vast datasets using Electron Backscatter Diffraction, so we need new techniques to automate analysis of them. Liverpool Earth Science began applying EBSD to rocks in the 1990s when the technique was quite new to geoscience, and I have been involved in general technique development and many case studies of deformed and/or metamorphosed rocks since then. I have devised new numerical analysis methods including one to analyse intracrystalline distortion. In 2021 this method was incorporated into Oxford Instruments’ Aztec Crystal software. This will provide further stimulus for use and development of the method, and I will continue to enhance my own code for EBSD analysis.

- Interactions between stress and chemical processes
I am interested in the fundamental interactions between stress and chemical processes in rocks, which influence a vast range of Earth processes. These processes include solid-state reactions under stress, reactive fluid flow in a deforming medium, and diffusion creep. Nature provides countless examples of structures where deformation is linked somehow to metamorphism; my aim is to provide a theoretical foundation to understand those links, and to test that theory in experiments. This is one theme in my NERC grant “Feedbacks between mineral reactions and mantle convection”, started in 2022.

- 4D visualisations of metamorphic reactions
I am working with a team based in Edinburgh on analysis of X-ray tomography data gathered during synchrotron experiments, thus enabling full 4D visualisations of metamorphic reactions (such as dehydration) and deformation. These huge datasets are full of novel insights; I assist with methods to extract relevant aspects of evolution and to model that evolution.

Research Interest 1

My research interests include small and large-scale aspects of Earth dynamics, and also the behaviour of metals and ceramics.

* Modelling of diffusion creep (pressure solution, Coble creep, Nabarro-Herring creep) in single and multiphase systems (rocks, metals and ceramics)
* Observation and modelling of dislocation creep, recovery and recrystallisation in single and multiphase systems (rocks, metals and ceramics)
* Observation and modelling of solid state phase transformations in single and multiphase systems (rocks, metals and ceramics)
* Applications of Electron Backscatter Diffraction in Earth sciences, metallurgy and materials science
* Fluid flow and chemical reaction in deforming systems
* Orogenic evolution and the significance of high pressure metamorphic rocks

Research grants

Feedbacks between mineral reactions and mantle convection

NATURAL ENVIRONMENT RESEARCH COUNCIL

March 2022 - February 2028

4D micro-scale quantification of coupled mineral dehydration and rock deformation processes

NATURAL ENVIRONMENT RESEARCH COUNCIL

January 2020 - December 2022

Calibration of a new model for mantle viscosity: the role of grain boundaries from bicrystal experiments

NATURAL ENVIRONMENT RESEARCH COUNCIL

November 2018 - June 2023

Fluid flow in the Earth: the influence of dehydration reactions and stress

NATURAL ENVIRONMENT RESEARCH COUNCIL

September 2012 - June 2017

The Feedback Between Volatiles and Mantle Dynamics

NATURAL ENVIRONMENT RESEARCH COUNCIL

September 2014 - March 2021

The Strength of the Lower Mantle

NATURAL ENVIRONMENT RESEARCH COUNCIL

June 2014 - December 2017

Feedback between physical and chemical processes during dehydration reactions.

NATURAL ENVIRONMENT RESEARCH COUNCIL

September 2005 - June 2009