Earth and Environmental Sciences

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Dr Hannah Hughes

Senior Lecturer in Exploration and Mining Geology

 H.Hughes@exeter.ac.uk

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Overview

Overview

I am an economic geologist and geochemist at the Camborne School of Mines, University of Exeter. My research interests include the metal budget of the mantle, the underlying controls (in space and time) for mineralisation in the crust, the ‘fingerprints’ of metallic mineralisation and the ancient histories of the oldest portions of the Earth’s lithosphere (cratons). I have further research pursuits in the generation and mitigation of gases in igneous rocks, particularly hazardous in some underground mines.


Research overview

Topics:

  • platinum-group elements (PGE) and highly siderophile elements
  • orthomagmatic Ni-Cu-PGE mineralisation
  • mantle xenoliths and diamond inclusions
  • lamprophyres and kimberlites
  • sulphide minerals
  • precious and critical metals
  • craton-specific exploration
  • gas outbursts and mines / generation of gases from igneous rocks


Geographic areas:

  • Bushveld Complex
  • Kaapvaal and Kalahari Cratons
  • North Atlantic Craton (NAC)
  • North Atlantic Igneous Province (NAIP)
  • British Palaeogene Igneous Province (BPIP)
  • Caledonides
  • Geology of Scotland and Northern Ireland  
  • Cornish Geology


Biography

  • 2017 - present: Lecturer in Geology, CSM, University of Exeter
  • 2015 - 2016: Postdoctoral Fellow, University of the Witwatersrand, Johannesburg, South Africa (Claude Leon Foundation and Centre of Excellence, CIMERA)
  • 2011 - 2015: PhD studentship, Cardiff University, UK
  • 2010 - 2011: MSc in Mining Geology, Camborne School of Mines, University of Exeter, UK
  • 2006 - 2010: MESc in Earth Science, University of Oxford, UK


Publications

See link


Professional Bodies

  • Applied Mineralogy Group (Committee Chair)
  • Mineralogical Society of Great Britain and Ireland
  • Society of Economic Geologists
  • Geological Society of South Africa
  • Women in Mining
  • Mineral Deposits Studies Group


Opportunities

If you’re interested in research collaboration, a PhD or an MSc, please get in touch. Similarly, if you’re interested in getting involved with the Applied Mineralogy Group of the Mineralogical Society of Great Britain and Ireland, I’d love to hear from you.


Links

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Publications

Copyright Notice: Any articles made available for download are for personal use only. Any other use requires prior permission of the author and the copyright holder.

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Further information

Research

 

Metals in the mantle

My research aims to understand the sources and budget of metals and sulphur spatially and through time to assess if/how this influences mineralisation in the crust. I do this by studying the controls on platinum-group element (PGE), chalcophile element and semi-metal (often classed as ‘critical’ and/or precious metals) mobility in the mantle, particularly the lithospheric (upper) mantle. These elements are intimately linked with the mobility of sulphur, often present as sulphide minerals, through the processes of partial melting and metasomatism. Mantle xenoliths and sulphide inclusions in diamonds can be used as direct insights into the abundance of these elements at depth. Lamprophyric rocks (produced by very small degrees of partial melting) can also provide useful insights into the composition of the upper mantle. By linking these xenolith, diamond inclusion and lamprophyre-based observations with the regional metallic fingerprints of large igneous provinces (LIP) and other magmatic rocks at the Earth’s surface, my co-workers and I assess how the metal basket of some ore deposits, such as Ni-Cu-PGE mineralisation, may be controlled by previous tectonic events (or ‘preconditioned’). This preconditioning may have the ability to change precious metal ratios (e.g., Pt vs. Pd) in mantle-derived magmas, and thereby change the metal basket of subsequent mineral deposits. The melting conditions and even source depth of mantle plumes may similarly have a significant effect on their PGE geochemistry and ultimately their fertility for precious metals - as investigated in an ongoing study with Jordan Lindsay.
 

Craton-specific exploration

Ultramafic rocks (comprising dunite, harzburgite, wherlite or serpentinite) are an important but poorly understood component of ancient crust (Archaean cratons) in greenstone belts and tonalite-tronjhemite-granodiorite (TTG) basement terranes. While many ultramafic units have been mapped and undergone limited petrographic studies, modern geochemical methods have not been widely applied to these rocks, in such a way as to constrain their origin(s) and the implications regarding Archaean geodynamic settings. Through a study by George Guice, we aim to generate a series of geochemical tools that will constrain the origin(s) of suites of Archaean ultramafic bodies from two contrasting cratonic regions – the Kaapvaal Craton and the North Atlantic Craton. This will reveal the extent to which ultramafic units of apparently different origin(s) became dismembered and juxtaposed against one another – in essence, the processes governing ‘cratonisation’ itself. An associated aim of the project will be to examine the relationship between Archaean igneous ultramafic processes and mineralisation potential (i.e., craton-specific mineralization).


Underground mine gas outbursts and lamprophyres

Lamprophyre dykes represent a serious hazard to mining excavations and developments in some areas of the Bushveld Complex. Falls of ground, catastrophic blow-outs and wall rock failures caused by explosive gas pockets are known to occur where lamprophyres have been exposed during mining. In collaboration with Bushveld mines and funded by the Royal Academy of Engineering, we investigate the  mineralogy and composition of these lamprophyre dykes and their gases, we can contribute pragmatic feedback to the mining industry with applied mineralogical and geotechnical advice on how to mitigate these dangers.

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