The origin of layering and platinum ores in the Flatreef of the Bushveld Complex: reactive porous flow in a sill complex?

Project Background
The Flatreef is a world-class platinum-group element (PGE) deposit recently discovered down-dip from existing mining and exploration operations on the northern limb of the Bushveld Complex. Current indicated resources stand at 42 Moz PGE, making it one of the largest PGE deposits on earth. The petrogenesis of the Flatreef mineralisation, and of PGE reefs in general, remains controversial; Some authors proposed that the ore layers formed at the base of large magma chambers, by gravitative crystal fractionation, density currents, or in situ phase saturation (Naldrett et al. 2009; Maier et al. 2013). Others suggested that the reefs formed through internal reorganisation of cumulate piles in response to percolating late magmatic melts and fluids (i.e. reactive percolative flow; Boudreau 2016). Moreover, reconnaissance studies on the Flatreef have recently identified out-of-sequence ages of certain ore layers, raising the possibility that the layering is due to injection of sills into largely consolidated cumulates.

Project Aims and Methods
The project is conducted in collaboration with CASE partner Ivanhoe Mines, as well as the British Geological Survey (BGS, co-supervisor) and the Commonwealth Scientific and Industrial Research Organisation (CSIRO, Australia, providing access to microXRF instruments). At the beginning of the project the student will collect a representative suite of samples at Ivanhoe Mines’ Flatreef mine, to be analysed geochemically and petrographically, using the analytical facilities at Cardiff University (element maps and mineral chemistry by FESEM, major and trace element concentrations by ICP-MS, Sr and Nd isotopes by mass spectrometry). A suite of approximately 10 samples will be mapped by desk-top XRF at CSIRO in Perth, Australia and then analysed by state-of-the-art CA-ID-TIMS at BGS to determine the age of the rocks. A similar number of samples from analogous horizons of the western Bushveld Complex will also be analysed, to facilitate correlation of marker layers. It is anticipated that the data generated will lead to an improved understanding of PGE reef formation and the origin of igneous layering in mafic-ultramafic intrusions, thereby producing more efficient exploration guidelines for PGE reefs in the Bushveld Complex and globally.


Candidate Requirements
The candidate needs to be willing to travel extensively. A passion for economic geology and igneous petrology is also essential, but other than standard undergraduate courses, no additional previous expertise in these fields is required.

CASE or Collaborative Partner
Ivanhoe Mines will make available for study > 700km of drill core in their facilities in Mokopane, northern Bushveld. CSIRO in Perth, Australia will provide access to their microXRF instruments to allow the generation of element maps. These are crucial to interpret petrological processes such as sulphide melt and silicate melt percolation, to select samples for geochronology, and to interpret the geochronological data.

Training
Through interaction with the partner company in South Africa and the supervisors, the PhD student will be trained in research methodology, mineral exploration techniques, and a variety of analytical and modelling techniques (e.g., ICP-MS, FESEM, microXRF, CA-ID-TIMS, Laser ablation ICP-MS, MELTS software). He/she will spend 5% of his/her time demonstrating in the School and thereby gain teaching experience, which is essential when planning an academic career. Further training will be provided through attendance of international conferences, notably the 2022 International Platinum Symposium. In addition, the PhD student will be involved in training of BSc students. The student will be a member of the SOLID research grouping within the school. The group holds regular meetings in which postgraduates participate. The SOLID group in turn interacts with the remainder of the School through joint seminars.

How to apply:

You should apply to the Doctor of Philosophy in Earth and Ocean Sciences with a start date of October 2020, including:

an upload of your CV
a personal statement/covering letter
two references (applicants are recommended to have a third academic referee, if the two academic referees are within the same department/school)
current academic transcripts.

In the research proposal section of your application, please specify the project title and supervisors of this project and copy the project description in the text box provided. In the funding section, please select ’I will be applying for a scholarship/grant’ and specify that you are applying for advertised funding from NERC GW4+ DTP.

If you wish to apply for more than one project please email [Email Address Removed].

The deadline for applications is 16:00 on 6 January 2020.

Shortlisting for interview will be conducted by 31 January 2020.

Shortlisted candidates will then be invited to an institutional interview. Interviews will be held in Cardiff University between 10 February and 21 February 2020