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New geomodels to explore deeper for High-Technology critical raw materials in Alkaline rocks and Carbonatites

Periodic Reporting for period 2 - HiTech AlkCarb (New geomodels to explore deeper for High-Technology critical raw materials in Alkaline rocks and Carbonatites)

Reporting period: 2017-08-01 to 2019-01-31

Of the 27 raw materials identified by the European Commission in 2017 as critical, nine are commonly found in association with alkaline rocks and carbonatites (heavy rare earth elements (HREE); light rare earth elements (LREE); niobium (Nb); fluorspar; phosphate / phosphorus, hafnium (Hf), tantalum (Ta) and scandium (Sc). In fact, there is a greater chance of a carbonatite complex having resources economic to mine than any other rock. Few of these ‘hi-tech’ commodities are currently mined within the EU and most have to be imported from across the world, creating concerns about security of supply.

HiTech AlkCarb is making a step-change in exploration models for alkaline and carbonatite provinces (Figure 1), establishing methodologies by which mineralogy, petrology, geochemistry and geophysics, including state-of-the-art interpretation of high resolution geophysics and downhole measurement tools, can be used to make robust predictions about mineral prospectivity at depth. The aim is to create new geomodels that will be the industry-standards for these rock types and will aid exploration in Europe. At present, the minerals exploration industry is using geological models that are over 40 years old. This is the largest global working group in this field and will give Europe a world-leading specialist position in exploration expertise and experience.

The objectives of the project are to:
1. Develop new geomodels to explore for ‘hi-tech’ raw materials (critical and related elements – REE, Sc, Nb, Ta, Zr, Hf, fluorspar) associated with alkaline rocks and carbonatites. The aim is to distinguish exploration indicators that suggest mineralisation at depths to 1 km.
2. Improve and develop interpretation of geophysical and downhole data to be able to make better interpretations down to 1 km in alkaline rocks and carbonatites.
3. Transfer into Europe expertise gained in African exploration to improve the chance of more ‘hi-tech’ element deposits being found within European countries.
4. Give Europe world-leading expertise so that European consultancy businesses can expand, in Europe and worldwide.
The HiTech AlkCarb team has made effective progress on the project goals. The majority of the geological and geophysical research has now been completed and the group is working to combine results from different tasks and work packages into the geomodels.
The geological research towards geomodels tasks are mainly complete. Fieldwork has been done in all of our natural labs (Germany, Italy, Greenland, Malawi, Mongolia, Namibia, South Africa and Scotland). Partners and invited Expert Councillors have taken part in workshops and field visits to gather information from recent academic and industry projects, and discuss hypotheses. Visiting the natural laboratories together enabled mentorship and peer-sharing, as well as highlighting gaps in our mutual understanding of mineralisation processes.

Much of research done has been published, or is on route to publication in international peer reviewed journals (see www.carbonatites.eu). Science highlights include papers on fenite alteration haloes around carbonatites, pyrochlore as a monitor for magmatic and hydrothermal processes, formation of the niobium tantalum deposit at Motzfeldt (Greenland), role of phosphorus in controlling the REE budget in carbonatites, formation of a fluorite deposit associated with volcanic rocks in Italy and a review of scandium.

Our new geomodels will incorporate environmental and social factors and a report has been prepared concentrating on the radioactive elements often associated with REE - the main public concern regarding mining of REE deposits. Our own experiences in Germany have been written up and shared with colleagues on other EU funded projects.

Geomodels and catalogues are now being produced, and include an online Catalogue of Alkaline Rocks and Carbonatites, a detailed representation of the Kaiserstuhl extinct volcano (Germany), including its niobium and REE-rich rocks; a series of conceptual models of alkaline and carbonatite complexes that will be published as 3D PDFs and contain geology, process mineralogy, environmental and social features in a comprehensive approach to exploration characteristics, and a mineral systems approach at regional, camp and deposit scales. We have already published a paper setting up the framework and terminology for this (Figure 2). We anticipate the timely release of our geomodels in the coming year.

Our research on improvement and use of geophysics aimed to provide information about geological structures at depth for the geomodels and improve interpretation of the geology from the geophysics results. Our field work at the Kaiserstuhl natural laboratory (Figure 3) is complete and written up. Highlights include the discovery of a new target area and other probably extensions of Kaiserstuhl hidden under sedimentary cover. Drone surveys were found particularly successful for detecting features at the scale needed for REE exploration.

Geophysics expertise was also applied at the Songwe Hill REE carbonatite project (Malawi). Ninety five boreholes (total 9.8 km) were logged with spectral gamma, conductivity, magnetic susceptibility, and gyro deviation to test the correlation between geophysical signals, geology and REE content. Interpretation is underway and shows a partial correlation.
The key legacy of the HiTech AlkCarb project will be the new geomodels that will become the industry standards to use during exploration, plus improved and state of the art geophysics, and a body of published work on key geological characteristics important in exploration. Highlights include the following:
• A new geomodel for the Kaiserstuhl complex (Germany) combining multiple geophysics studies with mineralogy, petrology and structure,
• Inclusion of process mineralogy, environmental and social aspects into the geomodels,
• Presentation of new conceptual models as 3D PDFs,
• A new mineral systems approach for exploration in carbonatites and alkaline rocks,
• An on-line catalogue of alkaline rocks and carbonatites,
• New techniques and protocols to apply geophysics to small, complex deposits,
• Stimulation of research community interest in further work on economic aspects of carbonatites and alkaline rocks,
• Enhancing European expertise and knowledge, including via our industry partners who are embedded into the project research and can take immediate advantage of the results and apply them in work with their clients.

We are conscious of our work in countries with less well established research structures and have included colleagues from Malawi, Namibia and Mongolia in our activities.

The Kaiserstuhl case study has provided key information about perceptions of mineral exploration in Europe and these have been shared via a workshop and project report. A public outreach day and lecture held in collaboration with a local museum at Kaiserstuhl, October 2018 was very well received.

Collaboration has been established with the H2020 PACIFIC project who will use Kaiserstuhl as a test area for their passive seismic exploration technique study.
SW Germany, Tentative, Variscan-Miocene Carbonatite REE-HFSE mineral system (Banks et al. 2019)
Robinson R44 Helicopter and crew at pre-flight check, holding up the magnetic sensor.
The main deliverables of HiTech AlkCarb are new industry and research standard geomodels.