Prof Helen Williams

My research interests center around the application of non-traditional stable isotope systems to understanding the formation and evolution of planetary interiors. I'm interested in topics such as accretion, core formation and the evolution of mantle redox state, isotopic tracing of depleted and enriched mantle components, element cycling and the oxidation state of subduction zones and the secular evolution of the Earth’s mantle.

The research tools I use are the stable (naturally occurring) isotopes of the transition metals (elements such as iron, zinc, copper, nickel and platinum), geological samples of planetary mantles like volcanic rocks and meteorites, and high-pressure and/or high-temperature experiments that simulate the conditions inside planetary interiors.  I'm also interested in using isotope tools to unravel surface processes such biogeochemical cycles and weathering at high latitudes and the export of metals from subglacial meltwaters into rivers and oceans, something that will become increasing important in our warmining climate. In the future I hope that we can also use these novel stable isotope systems to increase our understanding of how metals critical to the green energy transition can become concentrated in deposits near the Earth's surface. My research is primarily funded by the ERC (most recently the Advanced Grant 'EarthMelt' but previously the ERC Consolidator Grant 'HabitablePlanet') and NERC and also the Leverhulme Centre for Life in the Universe (LCLU).

My ERC Advanced Grant 'EarthMelt' focuses on magma ocean crystallisation on Earth, likely taking place after the intense Moon-forming giant impact and the planetary-scale melting this produced, and how this may compare to magma ocean processes on other terrestrial planets.  Magma ocean cooling crystallisation exerts considerable influence on planetary evolution because compatible elements (e.g. Mg and many of the precious platinum-group elements) are concentrated in solid phases while relatively incompatible elements (e.g. Fe and many trace elements) partition into melts. This elemental redistribution would have set the physical properties, rheology and chemistry of the Earth’s mantle, controlling its melting behaviour and the loss of heat from the Earth’s core, with implications for the Earth’s magnetic field, atmosphere, plate tectonics, and ultimately our planet’s habitability. While the theory behind these processes has been extensively explored, what is currently lacking is the geological or geochemical evidence that they ever occurred. The goal of my ERC project is therefore to find and develop novel stable isotope tracers of magma ocean crystallisation processes and then apply these to rocks and meteorites that sample planetary interiors, and I am very fortunate to have a great team of researchers working with me towards this goal.

In addition to the researchers and PhD students working with me on EarthMelt and other projects I've also mentored a number of independent research fellows (IRFs) funding by programs such as the Humboldt Foundation and Marie Skłodowska-Curie Actions, working on projects ranging from the evolution of the Earth's earliest continental crust to isotope tracing of subglacial weathering processes in the Arctic.  I'm always happy to mentor and support folk with fellowship applications to come and work with me - so please get in touch if you are interested in doing so!

My analytical work and isotope analyses are carried out using multi-collector inductively-coupled plasma mass spectrometer (MC-ICP-MS) in the clean lab geochemistry suite in Department. Much of my group's research uses the two Thermo Neptune Plus MC-ICP-MS instruments in our clean laboratories.  More recently, as part of my 'EarthMelt' ERC project we installed a new Thermo Neoma MC-ICP-MS instrument with a MS/MS collision-reaction-cell and multiple amplifiers equipped
with 1013 Ω and 1010 Ω  feedback resistors, which will enable us to analyse a wide range of different isotope systems where the elements we are interested are present at vastly different concentrations. The MS/MS collision-reaction-cell on the Neoma will also enable us to carry out gas-phase reactions to remove interfering species on elements of interest to us in terms of tracing planetary processes and will form a new and exciting development in geochemistry.