Mining is a wealth-creation industry that produces the metals and minerals essential to every sector of our economy. For instance, in 2018, Canada produced over 60 minerals and metals from almost 200 mines and 6,500 sand, gravel, and stone quarries valued at $47 billion, according to Natural Resources Canada.
Mineral exploration is at the front end of the mining industry, and the discovery of new orebodies is vital to meet the demands of a growing world population. However, finding new orebodies, particularly those rich enough to be developed into working mines, is hugely challenging.
The chance of a mineral discovery becoming a mine, for example, is estimated to be around one in a million. And even after a deposit has been defined, the odds that it will be economically viable are, at best, still only around one in a thousand.
Given such daunting odds, mineral exploration companies must be able to quickly and efficiently differentiate between areas of low or no mineralization and those containing potential mineralized deposits.
Metal Earth is a $104 million applied research and development program led by the Mineral Exploration Research Centre (MERC) at Laurentian University, in Sudbury, Ont., through strategic partnerships with five Canadian universities, six government geological surveys, and three international research centres.
The program seeks to provide the mining industry with the knowledge and tools to more effectively locate potential new orebodies.
“Mineral exploration research has never been done on this scale before,” says Ross Sherlock, the director of MERC. “Metal Earth is the largest geoscience program globally and has many different components, but the overall theme is to improve our understanding of the geological processes that govern metal endowment in the Earth’s crust.”
The program, he added, aims to develop a deeper understanding of the geological, geophysical, and geochemical markers that indicate the presence of ore deposits, to unlock the processes that lie behind mineral endowments, and to understand why similar geological structures have different mineral compositions.
The minerals exploration industry is facing significant challenges, such as increases in discovery costs and a general decrease in the quality of discoveries, which, Sherlock believes, come from the industry’s focus on near-mine, or brownfield, discoveries.
Very little exploration work, he added, is being conducted in greenfield areas, which are often located in remote areas and removed from existing infrastructure.
The program is initially focussing on the Archean volcano-sedimentary greenstone belts hosted by Canada’s Superior Craton. The Superior Craton is a crustal block that spans Quebec, Ontario and Manitoba, and also extends to the boundary between South Dakota and Minnesota in the United States.
Considered the mining heartland of Canada, the area is host to significant mining operations from the Abitibi district of Ontario-Quebec to the Red Lake region of northwestern Ontario. As a consequence, a vast amount of data is available about the area.
The program is attempting to determine the characteristics that differentiate metal-endowed areas from non- or less-endowed areas in these greenstone belts, which constitute around 48% of Canada’s metal wealth.
“The biggest wealth producer in the mining industry is the discovery of new orebodies,” says David Harquail, president and CEO of Franco-Nevada (TSX: FNV; NYSE: FNV), a leading royalty and streaming company headquartered in Toronto.
Harquail is on the advisory boards of Laurentian University’s Harquail School of Earth Sciences (HES) and MERC, which is the mineral deposit research arm of HES. In 2019, he donated $1 million to the Earth Metal program through the Harquail family’s Midas Touch Foundation.
“If we can discover new mineral deposits, this country will be much better off,” he added. “The most effective way to achieve this is to improve the fundamental science of mineral exploration and train the next generation of geoscientists.”
Digging deeper into Earth’s evolution
To develop a better understanding of the processes responsible for metal endowment, Metal Earth is investigating the various changes in the evolution of Earth’s atmosphere, hydrosphere, lithosphere, mantle, and geodynamic environment. All of which can be observed at the surface of the Earth.
“Metals are derived from the Earth’s mantle during differentiation and periods of crustal development and are supplied to the crust by magmas and fluids,” Sherlock says. “To be economically exploitable, these metals must be concentrated through natural processes into ore deposits.”
Our current understanding of metal endowment, he added, is based on the characterization of mineral deposits by placing them in the context of their regional petrologic and tectonic features.
Although this had led to sophisticated geological models of ore bodies that link a deposit to local- or district-scale processes, “we still only have a vague understanding of how the deposit relates to their larger geological environment,” says Sherlock.
He goes on to explain how deposits are the smaller-scale outcomes that originate from processes operating at much larger scales. Metal endowment arises from the evolution and interplay of larger tectonic elements and fluid pathways, and their connection to and interaction with the Earth’s mantle.
It is at the scale of ore systems that metals are sourced, mobilized and concentrated, with the differences in the tectonic elements and processes resulting in the differential endowment of areas with similar geology.
The program, therefore, is focussing on ore systems with the aim of developing the criteria needed to discriminate between the small, better-endowed areas and the vast expanses of no- or low-endowment.
“This will provide the exploration industry with the knowledge and tools to select areas of potential mineralization more effectively, thereby reducing the exploration risk and the cost of discovery,” Sherlock says.
By using a combination of geology, high-resolution seismic surveys, and magnetotellurics, the program’s researchers have collected and analyzed data from transects that cut across ancestral fault systems and volcanic and intrusive complexes and that exhibit variable and differential metal endowment.
By comparing the results from these transects, which can range from 40 km to 120 km in length, they are gaining a better understanding of the different processes that were active at the time of their formation and the processes that control metal endowment.
“So far, we’ve made significant progress in mapping fault systems that are highly endowed with gold and are associated with contrasts in the conductivity of their hanging walls, which tend to separate some of the highly endowed fault systems from the lesser endowed systems,” says Sherlock.
Metal Earth is currently in the fourth year of a seven-year program and has already made significant progress in meeting its goals. The program, for example, has led to the creation of the Superior Craton Geological Compilation map, which allows geoscientists to visualize, interrogate, and investigate geological information across jurisdictional boundaries.
The program has also produced 24 government survey reports and maps, generated 60 craton-scale geophysics and spin-off projects, and has shared its findings through 157 workshop and conference presentations, journal articles, master’s and doctoral theses, and fieldwork reports.
“Our findings could be used in greenfield environments in northern Canada, the cratons of West Africa, or the Guiana Shield of South America, for example, which have similar geology, allowing prospectors to more effectively locate areas of potential mineralization,” Sherlock says.