School of Earth & Ocean Sciences

Research Interests

Mineralogy, petrology, geochemistry and field geology with special emphasis on:-

The origin of mineral deposits including the platinum-group elements (PGE), gold, base metals - especially in volcanogenic massive sulphides and chromite,

The location, identification and paragenesis of PGE minerals using high resolution scanning electron microscopy and laser detection of trace precious metals in host minerals using an ICP-MS,

The study of magmatic and hydrothermal processes in rock formation,

Secondary reconcentration of PGE through weathering, soil and laterite formation and artificially in road dust and the urban environment,

Characterisation of different types of ophiolites and oceanic crust.

Research Achievements to Date

Platinum-group element mineralisation I discovered extraordinarily enriched Pt and Pd values in the Shetland ophiolite complex. This was of major importance because ancient oceanic crust, represented by ophiolites, was not previously thought to contain significant platinum-group element (PGE) concentrations. As a result I obtained a Royal Society Fellowship and MIRO industrially sponsored, EU, NERC and Open University grants which allowed me to explore the significance of this discovery. Some ophiolites are PGE-rich and others are barren and from a study of a number of ophiolites I deduced that the PGE-rich ophiolites result from greater degrees of mantle melting during the early stages of subduction of oceanic crust. I joined an ocean drilling cruise to the Hess Deep, discovered the first PGE minerals in the lower oceanic crust of the Pacific and showed that modern day oceanic mantle is still fertile in PGE. This is important because this mantle, formed at mid-ocean ridges, provides a potential source of PGE for extraction during greater degrees of melting at subduction zones. PGE were long thought to be immobile and I showed that during weathering mineralogical changes make the PGE more soluble. Weathering-related enrichments of PGE may be important sources of these metals in many environments. PGE are being introduced artificially into our cities through catalytic converters and I showed that Pt and Pd are accumulating in Cardiff road dusts.

Gold mineralisation I discovered a new low temperature hydrothermal gold mineralisation event in the Troodos ophiolite of Cyprus. This process could be widespread in the world's oceans and ancient oceanic crust. It may also act to generate gold deposits in rifting continental crust.

Ophiolites and oceanic crust. For my PhD thesis I dated the opening of the Atlantic at the latitude of Iberia at 135 Ma using K/Ar dating of brown hornblendes from oceanic gabbros. I showed that lizardite forms before chrysotile asbestos during serpentinisation. During a post doctoral fellowship I confirmed that the igneous complex in the Shetland Islands is an ophiolite complex on the basis of dyke and chromite geochemistry.

Current and Recent Research

This includes investigations of:-

• Research for the Royal Society Senior Brian Mercer Award for innovation for 2004 held jointly with Professor L Macaskie at Birmingham University for a project entitled:- Conversion of precious metals from road and urban waste into clean energy for transport and the built environment: ‘wastes into clean energy’ demonstration process.
• Development of exploration techniques for precious metals as part of my Royal Society Industrial Fellowship (2000-2004).
• Study of the processes of extraction of platinum-group elements (PGE) from the mantle and concentration of these elements in igneous complexes, including platinum-group mineral (PGM) studies of the PGE-bearing Ni-Cu sulphides of Jinchuan, China, PGE in layered intrusions eg the Freetown complex, Alaskan complexes and podiform chromitites.
• The effects of metamorphism and secondary remobilisation of precious metals with Professor H Sa at Salvador University and Professor M Suita at Ouro Preto and Dr W Wildner of CPRM all in Brazil, as part of the CYTED project on precious metals in ophiolites in Latin America and with C Blake in gossans at Las Cruces, Spain.