From arc magmas to ores (FAMOS): A mineral systems approach

Lead Research Organisation: The Open University
Department Name: Faculty of Sci, Tech, Eng & Maths (STEM)

Abstract

Society is dependent on a reliable supply of metals and minerals for economic growth, improved standards of living, and development of infrastructure. Population growth means that even with increased recycling and resource efficiency, new mineral deposits still need to be discovered. The efficient exploration for, and discovery of, new resources requires new concepts and new tools.
The Mineral Systems approach to exploration considers ore deposits on a lithospheric scale, in terms of the "ingredients", processes and environments that favour their formation. This approach amounts to a "source-pathway-trap" model, with an increased emphasis on predictive capacity, rather than just feature recognition. Historically, much research has focused on the trap, and characterisation of the ore deposits themselves; here we aim to focus deeper in the system by integrating ore deposit formation with concepts of magmatism that arise from igneous petrology and volcanology. Therein lies a challenge because extant models for porphyry systems are increasingly at odds with magmatic models for crustal construction and arc volcanism. Rather than seeing magmatic systems in terms of large, liquid-rich magma chambers, emerging petrological models for crustal magmatism are turning instead to crystal-dominated, volatile-bearing "mushy" systems that traverse most or all of the crust. The dynamics of such systems have important consequences not just for arc magmatism, but also for the chemistry of the volatiles that are exsolved. These same volatiles fuel mineralisation and this is the synergy that we aim to exploit by assembling a multidisciplinary team of researchers from economic geology, igneous and metamorphic petrology, volcanology, geochemistry, numerical modelling and fluid dynamics. Our team embraces almost everyone currently engaged in porphyry mineralisation research in the UK and capitalises on strong existing links between UK ROs and the mining industry, many of who are Project Partners.
The research will involve analysis of minerals from a wide variety of mineralised and barren settings using a wealth of modern analytical tools that enable determination of an extensive suite of trace elements and isotope tracers. As each trace element responds to magmatic processes in subtly different ways due to the affinity of different elements for different phases (minerals, melts and fluids), so the multi-element approach affords many advantages over conventional proxies in which the full potential of the Periodic Table is not exploited. The analysis of natural systems will be underpinned by high pressure and temperature experiments to establish the phase relationships of ascending arc magmas and the partition coefficients that capture the affinities of elements for certain phases. As fluid accumulation and migration is an essential, but poorly understood, final step in ore deposit formation, we will develop, in tandem with the geochemistry, numerical models for fluid-bearing mushy systems. Finally, consideration will be given to critical metals that are passengers through the main ore-forming processes, but constitute important, often under-explored, by-products of porphyry mineralisation.
The research proposed has a strong element of blue skies investigation, but a particular focus on outcomes that will benefit industry through improved exploration tools. Thus the project bridges the divide between academic and applied research in a way that is not normally possible through industry-funded projects. This bridging activity lies at the heart of the Highlight Topic call, specifically through the integration of new advances in the study of mineral systems, igneous petrology and geochemistry, with a view to identifying conditions that can act as pathfinders for new targets. A key outcome will be a range of trace element proxies that will enable the mining industry to establish the potential fertility of a magmatic arc on local to regional scales.

Planned Impact

We have taken an "embedded impact" approach with FAMOS. Stakeholders and beneficiaries have been involved with the development of the project from its initiation (including the initial Highlight Topic suggestion). The scientific content of the proposal was developed in discussion with representatives from industry, and the final consortium has assembled an Advisory Board that includes industry representatives so as to maintain two-way knowledge exchange and ensure development of impact. We have also engaged an international set of project partners (PP) who will extend the reach of our impact (see letters of support). The embedded impact will be delivered through various activities to support outreach, engagement and dissemination.

The key impact goal for FAMOS is to improve discovery rates of porphyry deposits by aiding exploration under cover, influencing decision making in the exploration process, reducing exploration risk and reducing the environmental impacts of drilling and associated disruptive fieldwork through more efficient prospectivity assessment.

There are four impact objectives within FAMOS:

1) A revised Mineral Systems model of porphyry deposit formation. This will lead to improved targeting at regional and igneous complex scales and better inputs to national strategies on mineral resources. Beneficiaries include PRIVATE SECTOR COMPANIES involved in mining, exploration and consultancy (e.g. PPs Anglo American, Rio Tinto, BHPBilliton, Freeport McMoRan), and NATIONAL AGENCIES charged with encouraging exploration and developing strategic resources (e.g. BGS and PP USGS).

2) New proxies for porphyry fertility. This will provide low-cost tools and approaches that will support improved decision-making during exploration. By using multiple proxies within a single sample, more data-rich exploration is possible, and in turn less sampling is required and less environmental impact is caused. Beneficiaries will include PRIVATE SECTOR COMPANIES involved in exploration, consultancy, and the provision of data and analytical equipment to industry (i.e. service companies, e.g. see PPs Olympus, Zeiss and SRK ES letters of support).

3) E-tech elements in porphyries. We will generate vital data for better global and national e-tech resource estimation. This facilitates improved targeting for specific e-techs during exploration, and improved metallurgical characterisation of them. Beneficiaries will be GOVERNMENT AGENCIES who advise on resource strategy (e.g. BGS, PP USGS), and POLICY MAKERS IN GOVERNMENT planning future clean energy strategies. PRIVATE SECTOR COMPANIES exploring for resources (see PP Anglo American letter of support) and end-users of e-techs will benefit through improved strategic knowledge of future supplies and the WIDER PUBLIC will gain through support of sustainable environmental technologies for a low-carbon society.

4) Outreach, education and training. We have planned activities to increase public understanding of resource issues (discovery, depletion, environmental and social impacts, the 'e-tech' concept), particularly through NHM outreach, and activities to encourage the uptake of the new model and proxies with professional geoscientists through training workshops, short courses and engagement at high profile conferences. Beneficiaries include the WIDER PUBLIC, PRIVATE SECTOR COMPANIES as publicly traded bodies and employers of skilled professionals and PROFESSIONAL BODIES such as the IOM3 and Mineral Deposits Studies Group (see letter of support) who support training and professional development for their members.

Publications

10 25 50

publication icon
Cox D (2019) Chalcophile element processing beneath a continental arc stratovolcano in Earth and Planetary Science Letters

publication icon
Deng C (2022) The Influence of Ridge Subduction on the Geochemistry of Vanuatu Arc Magmas in Journal of Geophysical Research: Solid Earth

publication icon
Liu E (2020) Petrologic monitoring at Volcán de Fuego, Guatemala in Journal of Volcanology and Geothermal Research

publication icon
Mason E (2023) Chalcophile element processing at an active continental arc volcano in Geochimica et Cosmochimica Acta

publication icon
Wieser P (2020) Chalcophile elements track the fate of sulfur at Kilauea Volcano, Hawai'i in Geochimica et Cosmochimica Acta

publication icon
Wieser P (2021) Encyclopedia of Geology

publication icon
Wieser PE (2019) Crystal scavenging from mush piles recorded by melt inclusions. in Nature communications

 
Description We have used the compositions of volcanic samples to place new constraints on the behaviour of elements during magmatism that are of economic importance, such as copper. These results have been published in peer reviewed journals. We have also pioneered the development of analytical techniques that allowed us to publish the first analyses of selenium concentrations in melt inclusions (tiny pockets of magma trapped in minerals).
Exploitation Route The data that we have produced will be valuable to a range of studies that aim to place constraints on the evolution of ore deposits, together with heterogeneity in the Earth's mantle and crust
Sectors Education,Energy,Environment,Other

 
Description Research objectives in relation to industry applications and the wider relevance of resources (especially copper) to the green energy transition have been communicated to UK government science advisors, HM Treasury, and via a government POST secondment (Dan Smith). We are widening our public engagement interactions with a number of online presentations and webinars reaching up to several hundred participants in the industry and investment sectors worldwide. Scientific outputs from the grant are gaining increasing coverage in the popular press and industry magazines because of their relevance to the energy transition.
First Year Of Impact 2018
Sector Government, Democracy and Justice,Culture, Heritage, Museums and Collections,Other
Impact Types Societal,Policy & public services

 
Title Laser ablation ICP-MS of silver and selenium in melt inclusions 
Description We developed the new capability to analyse selenium and silver in melt inclusions that are 50 microns in size (and larger) using laser ablation ICP-MS. 
Type Of Material Improvements to research infrastructure 
Year Produced 2020 
Provided To Others? Yes  
Impact This new capability allowed us to demonstrate that selenium partitions into fluids during shallow crustal processes and during subaerial eruptions. This finding will aid in the understanding of the toxic hazards associated with volcanic eruptions and the evolution of ore deposits in the crust. 
URL https://www.sciencedirect.com/user/identity/landing?code=t7Lu0ftPHAXFtJ4aPx5x3P92LyL6INfa2iB8NnFU&st...
 
Description BHP 
Organisation BHP Billiton
Country Australia 
Sector Private 
PI Contribution Presented initial project results to representatives from BHP in May and November 2018, highlighting industry-relevant aspects.
Collaborator Contribution BHP agreed to open up project results from two PhD projects they are supporting and provide access to samples from several of their operations.
Impact None
Start Year 2018
 
Description Barbara Kunz spoke about the FAMOS project at Soapbox Science 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact Dr Barbara Kunz, research project officer working in the geochemistry lab of the School of Environment, Earth and Ecosystem Sciences at the Open University (OU) spoke about the FAMOS project at Soapbox Science, Milton Keynes in June 2019. Soapbox Science is a novel public outreach platform for promoting women scientists and the science they do.
Year(s) Of Engagement Activity 2019
URL http://soapboxscience.org
 
Description Science-a-thon 
Form Of Engagement Activity Engagement focused website, blog or social media channel
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact A series of images & short caption on Twitter about about Barbara Kunz's day of science, to show what day to day science looks likes.
Year(s) Of Engagement Activity 2019