Structural controls on gold mineralization in the Palaeoproterozoic Mako Volcanic Belt, Senegal

Project Background
Orogenic gold deposits have strong structural controls on their location and geometry at all scales. However, it is unclear how structures link across different scales to control mineralization, what time scales are involved, or whether multiple deformation/mineralization events are necessary to create a large deposit. This project aims to improve our understanding of structural controls on gold deposits in four dimensions. The Paleoproterozoic of West Africa is a world-class Au province, with resources of c. 9896 tons. The Mako Volcanic Belt is located in the Kédougou-Kéniéba inlier in eastern Senegal. The belt comprises a package of volcanic and volcaniclastic rocks intruded by 2.2 to 2.0 Ga plutonic complexes. Two significant subparallel lineaments, the Main Transcurrent Shear Zone (MTZ) and the Sabodala-Sofia Structure (SSS) host economic gold mineralisation. The MTZ hosts the 2.6 Moz Massawa Au deposit. The SSS hosts 2.3 Moz Sabodala deposit and the Sofia satellite ore body.

Project Aims and Methods
The overall aim is to generate a spatially constrained metamorphic, structural and hydrothermal history of the MVB. This will be addressed through the following research questions (RQs):

1. How do key structural geometries in orogenic deposits vary and link across scales?
2. Is a change in stress regime associated with mineralization?
3. If so, what is the spatial and temporal scale of this change?
4. Can the above be used to predict the location and quality of future resources?

RQs1 and 2 will be addressed through detailed structural, lithological and alteration mapping of exposure and drill core at the m to 100 m scale. This will be extended to the μm-scale using petrography, SEM-EDS, EBSD, XRF and LA-ICP-MS analyses, and to the km-scale with geophysical interpretation. The spatial aspect of RQ3 will be addressed by integrating results from RQs1 and 2 with published work from the wider region, while the temporal aspect will be addressed by attempting to date mineralisation and deformation. Lastly, RQ4 will be addressed through a prospectivity analysis of the belt, incorporating fractal methods of assessing the structural controls on spacing and distribution of mineralization. This broad approach will allow the candidate flexibility to focus on the aspects they find most engaging over the course of the project.

Candidate Requirements
This project would suite a self-motivated candidate with an enthusiasm for fieldwork, especially in remote areas. A strong grounding in field mapping, structural geology, and mineralogy would be of great benefit. In addition, any prior experience of mineral exploration would be viewed positively.

CASE or Collaborative Partner
The CASE partner for this project is Randgold Resources. Randgold is a FTSE100 listed company whose activity is focused on exploring for, developing and mining economic gold deposits in Africa. Randgold own the permit area surrounding the Sofia and Massawa Au deposits, and will provide access, logistical support, and mentoring/supervision. As part of the CASE award, the successful student will spend at least 3 months with the CASE partner; this will largely be spent in the field in West Africa.

Training
The student will receive training in structural analysis on microscopic to regional scales, petrographic and mineralogical analysis via light microscope and state-of–the-art SEM-EDS and EBSD, and geochemical analysis via LA-ICP-MS. Cardiff and Randgold will provide joint training on the visualisation and analysis of industrial exploration data, and the application of fractal techniques to these data. The Randgold exploration team will support the student through on-the-job training in structural field mapping and diamond core logging, design, implementation and interpretation of geophysical and geochemical surveys, GIS, and applied mineralogy and metallurgy.