The Paper
Mercier-Langevin, P., Dube, B., Hannington, M.D., Davis, D.W., Lafrance, B., and Gosselin, G, 2007, The LaRonde Penna Au-rich volcanogenic massive sulfide deposit, Abitibi Greenstone belt, Quebec: Part I. Geology and geochronology. Economic Geology, v. 102, p. 585-609.
What it says
The LaRonde deposit is a very large gold deposit in the Abitibi Greenstone belt which, at the time this paper was written, was the largest gold mine in Canada. It had production and reserves of 8.1 Moz of gold, with a whole mess of base metals and silver in there, too. This mine is still going strong, with 5.6 Moz Au still in the ground (reserves plus resources). This paper is the first of three that covers the geology, geochemistry, and alteration of this important deposit in the far eastern Abitibi.This paper is mostly descriptive, reporting on the volcanic sequence that hosts the Au deposit. The volcanic package spans a range of compositions, from basaltic andesite through rhyolite. In contrast to some other deposits in the region, the host rocks of LaRonde were not a bimodal. The composition evolved throughout the couple of million years these rock were erupted and emplaced.
The authors also presented new U-Pb dates for the hanging wall and footwall of the 20 North ore lens, which was the active orebody at the time this paper was written. They showed a pretty tight window for the formation of the massive sulfide deposit around 2698 Ma. These new dates bracket the VMS mineralization. Because the LaRonde deposit is much less deformed than some of the other large Au-rich VMS deposits in the Abitibi, the timing relationships between Au and base metals is more clear; the gold at LaRonde was introduced syngenetically, rather than being introduced during later deformation.
Even though LaRonde is less deformed than some other deposits, from my point of view as a geologist who's spent most of his time in the Great Basin, these Archean greenstones are pretty beat up.
Why it matters
This is an important type of Canadian gold deposit. Understanding the kinds of rocks where they form helps us find more. Linking the Au mineralization to the VMS deposition, and not to a later structural event, also helps geologists understand their deposit and reduce the risks of discovery and mining.Why I read it
Last month I spent a week up in the Abitibi for work. The company I work for, Agnico Eagle owns LaRonde, and it's one of our major producers. The the corporate technical services group works out of a mine building near the property and I was heading up there for some training.While I was up there, I realized I really didn't know anything about the geology under my feet. I did know I was in the Abitibi Greenstone belt, home to "Archean gold deposits" as I learned in my Economic Geology course. I didn't know much more about the gold in this part of the world. I sought out some paper, any paper, really, about the deposit I was driving to every day that week. This is the one I found. Pretty good one. Might have to check out the rest of the series.
Odds and Ends
Heading up to this part of Quebec was an interesting experience. I've visited a handful of countries in my life, but I'm not really what you'd consider a "traveler". Before this trip I had been to Chile a couple times for field courses, Italy for a conference, and Vancouver to visit UBC. I stayed in Val-d'Or, a nice, if small town a few hours from Montreal. Turns out, this part of Quebec (and maybe the rest of it, too) is very French. I was not expecting that, but I got by.My last night there, I took the recommendation of one of the geologists in the modeling group and went to l'Entracte. It was Friday and packed. I had no reservation, so I took a seat at the bar and ordered a Coke (as a teetotaler, this isn't usually my preferred seat). people around me were talking, and generally having a good time. Except for one pair of guys at the other end of the bar talking mining, or maybe geology, everyone was having a good time in French.
I ordered the salmon and asparagus, easily the best meal I had that week. Soon an older, thin gentlemen sat down on my left and ordered a beer. When he paid, his brightly colored plastic money jumped from his hands and landed in "my" space. He said something in French, a joke I think, assuming we had a shared language. I nodded and smiled but understood nothing. Went back to my dinner.
The man stood and went to talk to the manager, or maybe owner, of the restaurant, used the phone. When he came back and sat down, he struck up a conversation in halting, heavily accented English. He introduced himself as Jean-Paul. He was waiting for his wife, who was coming to meet him for dinner. He asked where I was from and what brought me to the Abitibi. He was born in the town 78 years ago, in 1939 and had deep roots in the place. His brother owns the movie theater next door. Jean Paul has lived in Val-d'Or his entire life. After telling me this he paused and said, "And I am going to die here."
I was unsure whether he was just proud of his home or if there was something more certain in his proclamation. He explained that he had just been to the doctor that afternoon and had been diagnosed with pancreatic cancer. He had about six months to live. Besides his family, I was the second person he had told this, the first being the manager of the restaurant when he went to use the phone.
He told me about his diagnosis and his outlook. There was some tension in his face, maybe some fear, but mostly he seemed content. Not resigned. Not angry. This man who was just told he had six months to live, who had just learned he wouldn't see his 80th birthday was smiling and laughing, talking about his children and grandchildren and waiting for his wife. He apologized for his English one more time, and his wife arrived at the same time as the check for my dinner. I paid, and waited awkwardly for a pause in his conversation to tell him what a pleasure it was to meet him. Then I left, alone, as he was talking and laughing with his wife and another friend from town.
This short conversation at a bar on the east end of a little mining town in Quebec is still with me and still fills me with a certain wonder. During that short conversation I felt a bond with this stranger that was as strong as I feel with friends and acquaintances I've known for years. In that short time on a cool Friday night. I have very little in common with Jean-Paul. We are from different countries, speak different languages (for the most part), and have lived different lives. The only thing we really shared was our humanity.
It was a special experience, a singular feeling, bordering on sacred. It made the world feel small and connected.
I don't think I have the words to do justice to how that experience made me feel. I think it's why people travel. Not just visit a resort here and there, or go on a cruise, but really get out there and travel. It makes the world smaller and drives home the point that we really are in this together.
