Overview

Project Highlights:

  • Defining an exploration model for IOCGs in central Zambia
  • Development of a broad tectono-magmatic history during craton break up.
  • Fieldwork in southern Africa with industry partners

Iron-Oxide-Copper-Gold (IOCG) deposits are a diverse and complex type of hydrothermal ore systems that are the focus of much current scientific research in economic geology. They are major resources of Cu, Au, and other metals including rare earth elements (REE) and U. Zambia is one of the world’s major copper producers, hosting major resources in the Central African Copperbelt in the north of the country. However, copper was first discovered and mined in Zambia near Mumbwa in the central part of the country. These deposits, including Kitumba, comprise carbonate-sulfide-magnetite breccias associated with a suite of syenitic rocks.

Zambia straddles the margin between the Congo and Kalahari cratons, and during the Neoproterozoic, was the site of continental break up, which formed extentional rift systems of the Zambezi and Katangan belts from ~880 Ma, with a major compressional event, the Pan African Orogen, occurring at ~550-520 Ma. Magmatism ranging from ultramafic to syenitic was associated with the extensional regime, followed by granitoid intrusion during the collision. Recent work from the Leicester group has focussed on the ultramafic and mafic magmatism in the region, which is prospective for Ni sulfide mineralisation, and contains the unusual Munali Ni sulfide deposit (a carbonatite-associated sulfide-carbonate-magnetite-apatite system). However, it is clear that the Zambezi belt makes up a much broader magmatic province with a broad range of compositions. This project will focus on the synetic bodies that are intruded into a NW-SE trending belt that follow the Zambezi belt, but also cross into the Lufilian belt in central Zambia.

Research questions to tackled by this project:

  1. Where do the syenitic intrusions temporally sit in relation to the broader magmatic evolution of the rest of the Zambezi and Lufilian belts? For example, are the sulfide-carbonate-magnetite breccias of the IOCG deposits genetically linked to the unusual carbonatitic event at Munali?
  2. Does the magmatism in the Zambezi and Lufilian belts constitute a major Large Igneous Province in the NeoProterozoic?
  3. What control on IOCG mineralisation do the syenites have?
  4. How well do the Cu-Au deposits fit an ‘IOCG’ classification and thus what are the implications for mineral explorers and miners in the region?
Figure 1: The Zambezi Belt in southern Zambia hosts the Munali Ni mine (left of picture), which is hosted by mafic-carbonatitic intrusions with associated ultramafic-mafic-alkaline syenitic magmatism. The latter hare associated with Cu-Au mineralisation. Does the entire magmatic spectrum and range of ore deposit types constitute a Neoproterozoic large igneous-metallogenic province?

Methodology

The student will carry out fieldwork in Zambia to collect material of the IOCG mineralisation and associated syenitic and other intrusions from outcrop and drillcore, and integrate the following approaches to tackle the research questions above:

  1. Petrological, mineralogical (SEM and LA-ICP-MS) and geochemical (XRF) analysis to provide the key data for (3) and (4), including metallurgical implications.
  2. Fluid inclusion analysis from the ores will determine the key temperature and compositional contraints of the fluids to provide supporting evidence for (3)
  3. High precision U-Pb geochron on zircons from syenites and hematite from the IOCGs will carried out (through an application to NIGFSC) at NIGL to provide the temporal framework for (1-3).
  4. Integration of the results of this study, plus information from ongoing CENTA and industry-funded projects at Leicester will be able to build up a database to address (1) and (2).
  5. Interrogate the temporal, spatial and compositional data of the syenites and related IOCGs to provide key criteria for the exploration industry for deposits of this kind.

Training and Skills

The student will receive training in all analytical techniques required for the project including SEM, XRF and fluid inclusions analysis at Leicester, and U-Pb geochronology by CA-TIMS at NIGL. Industrial experience will be gained during fieldwork in Zambia, with the opportunity to spend time with the end users of the research. The student will be expected to attend one UK-based and one international conference each year and is encouraged to partake in field trips and workshops associated with these meetings.

 

Timeline

Year 1: Fieldwork in Zambia to collect initial set of samples from the Mumbwa distict including Kitumba deposit and spatially related syenites. Follow up work at Leicester to classify the petrology of the syenites and the mineralogy of the ores. Proposal to NIGL for U-Pb geochronology on syenites.

Year 2: SEM and Laser ablation work on the sulfide mineralogy to contrain the metal deportment within the deposits to provide metallurgical implications for industry. U-Pb geochronology. Further fieldwork in Zambia to collect specific samples for follow up mineralogical work.

Year 3: Synthesis of geochronological and geochemical data to develop a temporal framework for the magmatic evolution of the region. Preparation of industry-facing reports on implications for exploration, and mineral processing.

 

Partners and collaboration (including CASE)

The geochronology part of the project will be performed at NIGL under the supervision of Dr Simon Tapster, a research scientist with expertise in high-precision U-Pb dating, and who is involved in a project dating the mafic parts of the Zambezi belt. Julian Green is a Consulting Geologist at Geoquest in Zambia who has a wealth of experience and access to data and samples in Zambia. Simon Purkiss is the CEO of CASE partner Consolidated Mines and Investments; who are involved with the Kitumba Cu-Au project, which is the largest of the IOCGs in the Mumbwa area, along with the Munali Ni mine and other magmatic prospects in the Zambezi belt.

Further Details

Dr David Holwell <dah29@leicester.ac.uk, School of Geography, Geology & the Environment, University of Leicester