CSMs in Grenville: Geology, Issues and Challenges
Monday, November 18
9:00 a.m. to 4:00 p.m. – Room 308A
Regular rate: $150
Student rate: $25
Workshop Organizers: Abdelali Moukhsil, Mhamed El Bourki (MRNF) and Bertrand Rottier (Université Laval)
Critical and strategic minerals (CSMs) are key elements in the transition of modern societies to a green, less carbon-intensive economy. This explains the worldwide interest in exploring and exploiting CSMs, particularly in regions that are currently under-explored. The Grenville Province, with its substantial resources of various CSMs (graphite, rare earths, niobium, titanium, apatite, etc.), is currently undergoing intense exploration activity. This one-day workshop is intended for geologists, prospectors and students who want to learn about the geology of the various known CSM showings in the Grenville, as well as the issues and challenges associated with the exploration of these substances. Instructors will cover mineralization in rare earth elements, Ni-Cu, Fe-Ti-P and graphite during 30- to 45-minute presentations followed by two discussion periods. Representative samples of some lithologies and mineralization in the Grenville will be presented to help understand the subject.
9:00 a.m. – Rare Earth Elements ± Nb ± Ta Mineralization in the Grenville Province: Introduction and Examples – Abdelali Moukhsil et Mhamed El Bourki (MRNF)
9:30 a.m. – Rare Earth Element Deposits and Showings in Central Grenville – Bertrand Rottier (Université Laval)
10:00 a.m. – Break
10:15 a.m. – Discussion on the Rock Tables and Posters
10:45 a.m. – Exploring new concepts for migration of alkaline melts and perspective on Critical minerals in the Grenville province – Azam Soltanmohammadi (Commission géologique du Canada)
11:15 a.m. – Genesis and Exploitability of Graphite in a Grenvillian Context – Hugues Longuépée (IOS Services Géoscientifiques)
Abstract:
Graphite is a relatively common mineral in several Grenville areas. It is linked to the metamorphism of fine-grained sedimentary rocks with a high organic matter content. There are several other metals associated with the carbon for which the concentration is controlled by primary sedimentary processes. On the other hand, metamorphism plays a major role in the mineralogy and textural characteristics of the graphitic ore.
As it is the case for all industrial mineral ore, the value of the deposit is greatly influenced by the quality of the concentrate. For graphite, the value is dictated by the size of the flakes and the concentration of deleterious metals.
The presentation will briefly review the conditions that led to the grenvillian graphite genesis but will also touch on the parameters required to make the mining profitable and socially acceptable. Metallurgy, products, markets and environment will be some of the broached subjects. The presentation will mostly focus on the North Shore graphite, but aspects of other Grenville deposits will be presented while keeping in mind a more global context.
11:45 a.m. – Lunch
1:30 p.m. – Magmatic Ore Deposits Associated With Mafic-Ultramafic Intrusions (Ni-Cu-PGE and Fe-Ti-V-P) – Sarah Dare (UQAC)
Abstract:
The Grenville Province hosts numerous showings of Ni-Cu-PGE (sulphides) and Fe-Ti-V-P (oxide-apatite), associated with mafic-ultramafic intrusions, but very few are mined (with the exception of Lac Tio, the world’s largest Ti mine). This short course will review the fundamental notions of how these deposits form, with a focus on the geological context of the Grenville.
2:15 p.m. – The Potential Link Between Large Magmatic Provinces and Niobium Carbonatites: A Comparative Study of Carbonatites From Saguenay, Quebec – Nils Van Weelderen (UQAC)
Abstract:
The necessary conditions to form a carbonatite economically viable for niobium are poorly understood. Does the source of carbonatitic magmas impact the potential of a carbonatite to be mineralized? To address this question, four alkaline intrusions in the Waswanipi-Saguenay alignment (Quebec) were studied. These intrusions are grouped into two periods: 950 Ma-883 Ma for Crevier and Girardville, and 580 Ma-512 Ma for Saint-Honoré and Shipshaw. These intrusions differ in surface expression, association with nepheline syenites, ages, and niobium mineralization. New U-Pb ages on apatite have been obtained for the Shipshaw carbonatite: 554 ± 18 Ma for the smaller dykes, richer in niobium, and 512 ± 13 Ma for the more abundant dykes, depleted in niobium. Ar-Ar ages on mica (core to rim) were measured for the Girardville (915.6 ± 2.9 to 889.2 ± 2.9 Ma) and Saint-Honoré (586.1 ± 2.9 to 576.9 ± 2.9 Ma) carbonatites. Macroscopic and lithogeochemical studies showed that the Shipshaw dyke swarm does not contain associated silicate phases, is composed of carbonatite with an evolved geochemical signature, and is depleted in a suite of elements (including niobium). These observations, along with the orientations and ages of these dykes and their proximity to the Saint-Honoré intrusion, lead to the interpretation that the Shipshaw carbonatite is a late distal expression of the last magma injections at Saint-Honoré. The isotopic compositions of Saint-Honoré (87Sr/86Sr ratios between 0.70292 and 0.70313 and 143Nd/144Nd between 0.51205 and 0.51211) indicate a mantle source similar to that of the Fen carbonatite, the layered intrusion at Sept-Îles, and the Norwegian E-MORB suite, all of which are magmatic intrusions related to the Central Iapetus Magmatic Province (CIMP, 615 to 550 Ma). This suggests that the most mineralized intrusion (Saint-Honoré) is linked to the last episode of activity of the CIMP. The carbonatites of Saint-Honoré and Shipshaw are located at the junction of two diapirs and at the contact between the Lac Saint-Jean Anorthosite Suite and the Grenvillian basement, which may have facilitated magma ascent. This study thus suggests that alkaline intrusions derived from mantle plumes associated with large crustal structures are more likely to be mineralized in niobium. A dyke swarm of carbonatite like that of Shipshaw could be a distal indicator of a larger carbonatitic intrusion.
2:45 p.m. – Metasomatic IOCG, IOA-REE and Affiliated Critical Mineral Deposits: Breakthroughs, Challenges and Solutions – Louise Corriveau (Commission géologique du Canada)
Abstract:
Metasomatic iron and alkali-calcic (MIAC) mineral systems and their iron oxide copper-gold (IOCG) and affiliated deposits have a major role to play in the development of critical and strategic minerals in Canada and Quebec. The calculated resources of their deposits (reaching 11 billion tons at the Olympic Dam deposit in Australia) total 14 of the 34 critical minerals on the Canadian list (Bi, Co, Cu, F, Fe, Mo, Nb, Ni, P, PGE [Pd, Pt], REE-Y, U, V, W, Zn), in addition to Ag, Au, Pb, and Re. Potential by-products are abundant due to the selective enrichments of metals in the minerals being mined. As a result, the US and Canadian governments are investing millions of dollars in the development of the NICO Au-Co-Bi-Cu deposit in the Northwest Territories. Global comparisons undertaken by the Targeted Geoscience Initiative (TGI) program show that Canadian MIAC systems including those of the Grenville Province share the metasomatic and geochemical evolution and mineralization types of MIAC mining districts around the world (e.g., Olympic Dam, Australia). The comparisons enable to broaden the MIAC metallogenic model to deposits with a wide range of iron and iron oxides contents. Accordingly, the model now accounts for the genesis of iron oxide-apatite-Fe-REE-P (IOA), IOCG, iron sulfide copper-gold (ISCG), skarn (Fe, W or Pb-Zn rich), skarn-hosted U-REE, metasomatic Fe-rich Au-Co-Bi or Ni, albitite-hosted U, Au-Co or Mo-Re, and five-element vein deposits. The model and case studies are supported by new criteria, protocols and tools for geological mapping, prospectivity assessment and exploration. The outcomes optimize the workflow for mineral exploration and increase chances of discovery for critical and strategic mineral deposits, including in the Grenville Province. Beyond these breakthroughs, challenges remain with the poor resolution of the national gravity data, which would make it impossible to identify the gravity anomaly of the supergiant Olympic Dam deposit, let alone the non-magnetic to low magnetic MIAC deposits rich in critical minerals. Furthermore, the key mappable prospectivity criteria—alteration facies—are not systematically described and documented during regional geological mapping and exploration campaigns. Possible solutions include stakeholder ownership of the breakthroughs made by TGI, and a willingness to change some of our current survey and exploration paradigms in Canada.
3:15 p.m. – Break
3:30 p.m. – Discussion
4:00 p.m. – End of Course