Dec '11/Jan '12

Understanding the greater picture

Distinguished Lecturer shares insights on iron oxide copper-gold deposits

By A. Lopez-Pacheco

A pioneer in exploration research, Hamid Mumin was one of the first to look into iron oxide copper-gold deposits in the Great Bear Magmatic Zone in the Northwest Territories. His career as a geologist and researcher spans more than two decades involving resource discoveries and developments around the world.

As a geology professor at Manitoba’s Brandon University, Mumin has published numerous papers and technical reports on economic geology and is the co-editor of Ore Mineral Atlas, as well as Exploration for Iron Oxide Copper-Gold Deposits: Canada and World Analogues. 

A former president of Geoscientists Canada, Mumin joins the roster of speakers in this season’s CIM Distinguished Lecturers Series to share his insights on iron oxide copper-gold deposits in a genetic context and the significance of these deposits to exploration.

CIM: How did you get involved in the study of iron oxide copper-gold deposits?

Mumin: It started with a request from Fortune Minerals in 1995, which was working in the Great Bear Magmatic Zone in the Northwest Territories. The Geological Survey of Canada had done some preliminary work the previous year that suggested there may be a new mineralization type in that region; namely, iron oxide copper-gold deposits, which had never been explored in Canada.

CIM: What was the result of the early research you carried out? 

Mumin: We made a very promising discovery by applying the exploration model for iron oxide copper-gold deposits, and that discovery is now Fortune Mineral’s NICO Deposit, which is being developed. It became evident that there was great potential for this type of mineralization to occur in the Great Bear Magmatic Zone.

CIM: Despite your findings, there remains quite a lot of controversy around the iron oxide copper-gold type mineralization. What is your view on this?

Mumin: There are still a number of people who don’t appreciate the fact that many scientists around the world have actually classified and grouped a particular type of deposit under the category of iron oxide copper-gold and associated deposit types. They wonder why they are lumping such a wide range of seemingly disparate deposit types under this classification. So there’s a great need for some clarity as to what we really mean when we refer to iron oxide copper-gold type proper. We’re not actually lumping it all together. There is a very clear and distinct definition for iron oxide copper-gold type proper, and when we look at the genetic context – how these deposits form – it becomes very clear as to why there is a great variety of associated deposit types that can form within the same systems, at the same time, in the same areas, and by similar and related processes.

CIM: What is the reason for the variety?

Mumin: These deposits generally form in the heart of volcano-plutonic complexes. The fluids and gasses coming off the magma cause mineralization, and when those gasses and fluids react with different rocks in different ways and under different circumstances, they produce a variety of disparate but related types of mineralization. The magmatic-hydrothermal processes produce deposits that can appear very different, even though they’re all related to a single greater event. Going back to the controversy, what’s important is not the classification or whether the mineralization types should be grouped together. What’s important for exploration is the fact that they are genetically related. If you understand those genetic and spatial relationships, then this gives you a very powerful exploration tool. In other words, if you find one type over here, then you know you might be able to find other related mineralization elsewhere, and we know something about where that elsewhere might be, because we understand the relationships between them.

CIM: So this represents a very significant discovery for exploration?

Mumin: Yes. If you understand the greater picture, you can be more effective in your exploration and you can simultaneously search for a number of deposit types as opposed to one thing only – and we certainly see tremendous evidence of that in parts of the Great Bear Magmatic Zone. Because it’s so far north and the rocks are so well-exposed, it’s a great opportunity for geologists to walk the ground and visually see all these relationships. Very often, you’re speculating as to what’s happening in between outcrops, but in the Great Bear Magmatic Zone, you have huge areas where it’s almost continuous rock exposure. We can map and document very clearly what the relationships between the deposits are. This is probably the greatest contribution that this remote area has made to the field of mineral deposit geology and exploration.

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