NERC GW4+ DTP PhD studentship: Understanding the origin of alkaline igneous provinces and associated critical metal mineralisation: the Chilwa Alkaline Province, Malawi

University of Exeter - College of Life and Environmental Science

This project is one of a number that are in competition for funding from the NERC Great Western Four+ Doctoral Training Partnership (GW4+ DTP). At least 4 fully-funded studentships that encompass the breadth of earth and environmental sciences are being offered to start in September 2017 at Exeter. The studentships will provide funding for a stipend which is currently £14,296 per annum for 2016-2017, 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.

Main supervisor: Prof Frances Wall (Camborne School of Mines, University of Exeter)

The Chilwa Alkaline Province (CAP), in southern Malawi, is one of the classic areas of carbonatite and alkaline magmatism. It comprises large alkaline intrusions ranging from Mlanje, at approximately 640 km2 and rising to 3000 m, to smaller intrusions and minor plugs and dykes. These intrusive centres, mainly late Jurassic, are remarkable for their lithological diversity, including granites, quartz syenites, syenites and trachytes, nepheline syenites and phonolites, ijolites and nephelinites, and a plethora of dykes and carbonatites with associated fenites. They are characteristically associated with critical metals deposits, especially REE and Nb. Critical metals are essential for a range of essential environmental and digital technologies. They are difficult to substitute, and at risk of supply disruption because of their limited number of sources. Better exploration models will help diversity and secure critical metals supply.

The genesis of alkaline provinces such as the CAP is contentious, with two main controls advocated: a structural control, in the lithosphere (Woolley, 1987); and a mantle plume derived control (e.g. Bell, 2001). The CAP is an example of a province considered to be emplaced through structural control in the lithosphere, with up-doming, lithospheric focussing and rifting ascribed to an early stage of the East African Rift (Woolley, 1987). However, this hypothesis is supported by geochemical analyses from only a few intrusions in the north of the province, and limited Ar-Ar and fission track data. There is no holistic model for the critical metal mineralisation.

The project objective is to produce a model for the CAP that relates the processes that concentrate the resources, especially REE, P and Nb, in certain intrusions, to the fundamental petrogenesis. Project partner, Mkango Resources, operates in Malawi and can support fieldwork to obtain samples from the poorly-studied intrusions of the southern CAP (Fig 1). The Natural History Museum (NHM) project partner will facilitate access to collections of material from the northern CAP and aid whole-rock geochemical analyses. The project will use state of the art spatially-resolved geochemical techniques. The results will be an important step in the development of a mineral deposit model for this area, which can be applied to other alkaline igneous provinces globally.

The project will run alongside two large consortia research programmes: SoS RARE ( researching mobility and concentration of REE and HiTechAlkCarb ( a new European level project developing exploration geomodels for alkaline rocks and carbonatites.

See for full details and how to apply.

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South West England