Platinum-Group Element and Isotopic Geochemistry of Lamprophyric Dykes from the Bushveld Complex, South Africa: Implications for Mapping Precious Metals in the Mantle as a Mineral Exploration Tool - Environmental Science - NERC GW4+ DTP PhD studentship Ref: 2801

About the award

This project is one of a number that are in competition for funding from the NERC Great Western Four+ Doctoral Training Partnership (GW4+ DTP).  The GW4+ DTP consists of the Great Western Four alliance of the University of Bath, University of Bristol, Cardiff University and the University of Exeter plus six Research Organisation partners:  British Antarctic Survey, British Geological Survey, Centre for Ecology and Hydrology, the Met Office, the Natural History Museum and Plymouth Marine Laboratory.  The partnership aims to provide a broad training in earth and environmental sciences, designed to train tomorrow’s leaders in earth and environmental science. For further details about the programme please see http://nercgw4plus.ac.uk/

The studentships will provide funding for a stipend which is currently £14,553 per annum for 2017-2018, research costs and UK/EU tuition fees at Research Council UK rates for 42 months (3.5 years) for full-time students, pro rata for part-time students.

Supervisors:

Lead supervisor: Dr Hannah Hughes
Co-Supervisor: Dr Iain McDonald
Co-Supervisor: Prof Chris Jeffrey
Co-Supervisor: Prof Judith Kinnaird
Co-Supervisor: Dr Grant Bybee
Co-Supervisor: Prof Chris Hawkesworht
Co-Supervisor: Dr Simon Tapster (BGS)

Location: Penryn Campus, Cornwall

Project description:

A suite of lamprophyric dykes have recently been described cross-cutting the Bushveld Complex of South Africa (Hughes et al., 2016) – the world’s largest layered intrusion and storehouse of Cr, V and platinum-group elements (PGE) mineral deposits.  Despite the Bushveld Complex being one of the classic areas for igneous and economic geoscience research in the world, surprisingly little is known about the provenance of the magmas and metals from which it formed and mineralised.  The lamprophyre dykes cross-cutting the Bushveld are substantially younger than the Bushveld Complex itself (Hughes et al., in prep) and are thought to have been derived from very small degree partial melts of the subcontinental lithospheric mantle (SCLM). Via time-integrated radiogenic isotopic compositions of the lamprophyres, spatial and temporal changes in sub-Bushveld SCLM composition may be identified.

 

Image 1: Lamprophyre dykes in drill core. Image 2: View over the Western Limb of the Bushveld Complex

Project Aims and Methods

A significant aim of the PhD project is to ascertain the controls on PGE behaviour and geochemistry: a paradox of lamprophyric rocks (including kimberlites) is that their PGE (and Au) abundance is higher than would be expected given the very low degrees of partial melting required to form them (McDonald et al., 1995). This observation contradicts ‘traditional’ partial melting models thought to dictate the ‘fertility’ of mantle-derived magmas for PGE and Au. By contextualising PGE geochemical data with the petrography, mineral chemistry and isotopic compositions of lamprophyric dykes (and comparing these with appropriate mantle/mantle-derived lithologies), the PhD studentship will identify the processes governing the (re)distribution of these elements in the upper mantle.

The proposed PhD study will establish the radiogenic isotopic and PGE characteristics of the dykes (with some reference samples from kimberlites and other lamprophyres) and thereby couple these geochemical tools. Thus the objectives of the studentship are to:
1. Gain insights into the precious metal budget of the mantle through time.
2. Assess if this metal budget and it’s ‘fingerprints’ impact upon the location and characteristics of major mineralised metal deposits, e.g. the Bushveld Complex itself.
3. Develop PGE as a tool for understanding lamprophyric rock petrogenesis, possibly towards kimberlite (diamond) exploration.


Candidate

Candidates suited to this PhD will have an interest in mantle petrology, mantle processes, geochemistry (including isotope geochemistry and platinum-group element geochemistry), and economic geology. The candidate will be collaborative, and keen to travel and visit various labs across the UK and in South Africa (RSA).

 

CASE Award Description

This award has CASE support from British Geological Survey (BGS)  via BGS University Funding Initiative (BUFI) with a total budget of £10,000. More information can be found on the BGS website.


Training

The project will provide training in petrology (including SEM, EPMA and LA-ICP-MS), geochemistry and associated analytical techniques (for major and trace elements by ICP-OES, ICP-MS and XRF, and PGE by NiS fire assay with ICP-MS).  Isotopic analyses techniques relevant for Sm-Nd, Rb-Sr and/or Lu-Hf systems will be provided. The student will be encouraged to undertake specific additional training courses (through NERC Advanced Skill Training and external courses) as required by the needs of the project or their own specific interests (for example in ArcGIS/Datamine/Leapfrog/MVE Move exploration geographical information systems).


References:

Coe, N., Le Roex, A., Gurney, J., Pearson, D.G. and Nowell, G. 2008. Petrogenesis of the Swartruggens and Star Group II kimberlite dyke swarms, South Africa: constraints from whole rock geochemistry. Contributions to Mineralogy and Petrology, 156(5), 627-652.

Hughes, H.S.R., Kinnaird, J.A., McDonald, I., Nex, P.A.M., Bybee, G.M. 2016a. Lamprophyric dykes in the Bushveld Complex: the lithospheric mantle and its metallogenic bearing on the Bushveld large igneous province. Applied Earth Science, 125(2), 85-86.

Hughes, H.S.R., McDonald, I., Loocke, M., Butler, I.B., Upton, B.G.J., Faithfull, J.W. 2017. Paradoxical co-existing base metal sulphides in the mantle: The multi-event record preserved in Loch Roag peridotite xenoliths, North Atlantic Craton. Lithos, (Special Issue on European Mantle). DOI: 10.1016/j.lithos.2016.09.035

Janney, P.E., Shirey, S.B., Carlson, R.W., Pearson, D.G., Bell, D.R., Le Roex, A.P., Ishikawa, A., Nixon, P.H., Boyd, F.R. 2010. Age, composition and thermal characteristics of South African off-craton mantle lithosphere: Evidence for a multi-stage history. Journal of Petrology, 51(9), 1849.

McDonald, I., De Wit, M.J., Smith, C.B., Bizzi, L.A., Viljoen, K.S., 1995. The geochemistry of the platinum-group elements in Brazilian and southern African kimberlites. Geochimica et Cosmochimica Acta, 59(14), 2883-2903.


Entry requirements:        

Applicants should have obtained, or be about to obtain, a First or Upper Second Class UK Honours degree, or the equivalent qualifications gained outside the UK.   Applicants with a Lower Second Class degree will be considered if they also have Master’s degree.  Applicants with a minimum of Upper Second Class degree and significant relevant non-academic experience are encouraged to apply.

All applicants would need to meet our English language requirements by the start of the  project http://www.exeter.ac.uk/postgraduate/apply/english/.

Applicants who are classed as International for tuition fee purposes are not eligible for funding.

Summary

Application deadline:7th January 2018
Value:£14,553 per annum for 2017-18
Duration of award:per year
Contact: PGR Recruitment Officepgrenquiries@exeter.ac.uk

How to apply

In the application process you will be asked to upload several documents.  Please note our preferred format is PDF, each file named with your surname and the name of the document, eg. “Smith – CV.pdf”, “Smith – Cover Letter.pdf”, “Smith – Transcript.pdf”.

•       CV
•       Letter of application outlining your academic interests, prior research experience and reasons for wishing to
        undertake the project.
•       Transcript(s) giving full details of subjects studied and grades/marks obtained.  This should be an interim transcript
        if you are still studying.
•       If you are not a national of a majority English-speaking country you will need to submit evidence of your current
        proficiency in English.

You will be asked to name 2 referees as part of the application process however we will not contact these people until the shortlisting stage. Your referees should not be from the prospective supervisory team.

The closing date for applications is midnight on 7 January 2018.  Interviews will be held at the University of Exeter between 5 - 16 February 2018.

If you have any general enquiries about the application process please email pgrenquiries@exeter.ac.uk.  Project-specific queries should be directed to the supervisor.

During the application process, the University may need to make certain disclosures of your personal data to third parties to be able to administer your application, carry out interviews and select candidates.  These are not limited to, but may include disclosures to:

• the selection panel and/or management board or equivalent of the relevant programme, which is likely to include staff from one or more other HEIs;

• administrative staff at one or more other HEIs participating in the relevant programme.

Such disclosures will always be kept to the minimum amount of personal data required for the specific purpose. Your sensitive personal data (relating to disability and race/ethnicity) will not be disclosed without your explicit consent.