23. Models, Drobbles, and Data in Magmatic Sulfide Deposits

(upbeat music) - Hi everyone, this is Discovery to Recovery, where we bring you geoscience stories from the World of War deposits. This podcast is brought to you by the Society of Economic Teologists and is sponsored by Goldspot Discoveries. I'm Ann Thompson, a partner in Petri Science Consultants and I'm your host for this episode. Magnetic sulfide deposits is our big thing today, and we wanted to let you know about a special symposium coming up in May, 2022. The virtual platinum symposium is run by early career researchers for early career researchers. There will be three days of student talks and keynotes by post-docs in the field, and it's a prequel to the main platinum symposium scheduled for 2023. And Ann and Benefit are the pre and post conference workshops to develop skills and software and methods relevant to magnetic sulfide research. Special thanks to Iagod for sponsoring and senior researchers in the field who have offered to provide feedback to students submitting abstracts. If you're interested in hearing about the event or submitting an abstract, head over to the mag soul, that's MAG, SUL, website hosted by Laurentian University, or find them on Instagram, Facebook, and Twitter, at Platts Symposium, 2022. That's PLAT Symposium, 2022. Today, we're really thrilled to bring you three guests who provide insights into intriguing developments in our understanding of magnetic sulfide deposits, from fundamental research to critical factors in exploration. First, we spoke to Peter Lightfoot of Lightfoot Geoscience Inc, and was also an adjunct professor at Western University. Peter's career has combined research and exploration in an unusual way, and he has great insights. - I want to hook you into the world of magnetic sulfides. - That's a really interesting question. I have to ponder this one a little bit, but starting off, I had a fascination with geology as a kid. I lived in South Wales, a really beautiful part of the world. There were lots of structures and lots of complicated carbonate sequence of fossils and everything, and I just loved it as a kid, a really majestic geology. And my parents were the type of person who wanted me to have the life I wanted and wanted to do what I wanted to do, and so they gave me the full capability to go and either ruin myself or actually make something with my career. I caught on about science pretty late. It was a slow developer in early school, and finally I realized the value of science. I had a really great geography teacher, as most geologists probably do at one point in their life. Guy called Terry Morgan, who just got me so into the landscape and the impact of geology on landscape. That set me up. I chose not to go and do geography. I wanted to go do geology. I landed up at Oxford, and it was a pretty dynamic place to be back in those days. There were all sorts of people doing really exciting research like the early days of uranium-led geochronology and subbasalt research and things like that, all the sort of interesting stuff. But in my third year, there was this chap who was scurled away in the office on the third floor, and a guy called Dick Stanton, and the father of economic geologist in my life, I introduced myself, I ended up with a couple of seasons of tutorials with the guy. Really interesting guy, because he had incredibly unorthodox ideas about how water deposits were formed. And it was really great to hear someone questioning continental drift and saying, well, how does it all fit together and how do these little bodies fit into this story? And Dick was very formative in my interest in water deposits. And he's the guy who basically introduced me to Tony Noldert, who also was on sabbatical at around about the same time. Tony was, oh, another nickel student here, so I-- we soon hooked up, and I agreed to get a Toronto. I have a really exciting project on the NCs where it's complex to work on. And it got me into the whole world of nickel. Tony's team at U of T was just-- it was a workhorse team, strong competition, great work ethic. Everyone was really doing great thesis topics. And I so benefited from that. But that's really dynamic environment for two years and finished off there. And that was real fun. But I kind of-- the one thing I didn't want to do was spend my life doing courses. I actually wanted to do research. And that's what took me back to the UK to do my PhD. I wanted to escape the course circle. And Chris Hawkes worked up me on to do a project term. I kind of was interested in flood basalts by that time, because in Cs, whereas in the roots of the Peru flood basalt province, so it spoke well. Tech-and-trap, another good example. So I went off to do that and spent as about two and a half years in Milton Keynes working with Chris very much at a geochemistry study, no economic implications. But it turned out that was all formative stuff about how you use that type of science and understanding the geochemistry of order deposits. And gave you a foundation to carry on to the next step? Well, so yeah, it was a total foundation. And during that, I kept in touch in Toronto. I came back right after finishing, got married, and then carried on working as a postdoc with Tony. That was a very clever view, actually. That plan you had. It was carefully worked out. And it was great. Tony had already, by that point in time, developed some quite serious contacts in the Soviet Academy of Sciences. He wanted to work on the real skewers. He was really-- it was the one order deposit, the one nickel system he wanted to get to work on. And he had a visiting scientist in an exchange program, a guy called Nick Gorbachev. Nick, can I just connect it? And Nick started bringing basalt samples over in aeroflop flights, which was just fantastic. Like the whole figure of these of the flood basalt switch, after my deck and stuff just was perfect. And that basically was the start of a serious neural project where we started to receive increasingly large numbers of samples. And then we started to get samples from the ore bodies themselves and work through and understand the relationship between the basalt, the intrusions, and the mineralization. So it was a pretty exciting time. It was the period of perestroika and clasnost and everything was opening and everything was open. And it was a fantastic time. Everyone wanted to talk to you and understand Western science and help you to apply new technologies in analyzing samples and new ideas and understanding ore bodies. So it was just fantastic. The real thing that made biggest difference from me at that time was access to relatively new technology called the inductively coupled plasma mass spectrometry, ICBMS. And at the time, it was around, but not really developed very well for geological materials. And one of my colleagues, Will Davide, basically set up one of the early systems to be able to determine very low abundances of elements with very high precision in accuracy. And that triggered a pile of papers that came out of that in the recognition of the metal depletion signal in the basaltic rocks it was a really exciting, exciting time. That opened a lot of other opportunities. I could rattle on forever here, but it opened up the door to West Greenland to the mid-continent rest and ultimately working on Sudbury. So the themes came through. And when you think about research, and you go, I've been doing a research project one year, two years, three years. This has been a research project of a lifetime now to work through and understand these different relationships. But somewhere in there, I mean, it's a lifetime of research. But in actual fact, did you end it up in industry? So if you're listening to your talk, you wouldn't actually peg you as an industry exploration geologist, which you are, and a very good one. I've been in, you know, I started my career as a postdoc. I did about 10 years with geological survey looking after analytical methods and then understanding the geology of nickel and ontaria. But it was really the discovery of Voices Bay that got me hang on. I mean, I need to change my theme and become an exploration geologist much more, much more fun, much more dynamic. And I was at the position at encoder time to work on Voices Bay just before the acquisition by Diamond Fields. And that's right. That was exciting. It was exciting times for Canada as a whole. Yeah, so that opened the door. And I ended up just falling in love with exploration. Ever since then, that's been my main driver. But underpinning all of that has been all of this knowledge of the ore deposits, knowledge of the mineral systems, and the applications of new technology to light geochemistry in supporting exploration. So if I hadn't spent the first formative part of my career, you know, 10 or 15 years, including academia, to set me up, I probably wouldn't have been able to bring that into my experience in exploration. Side note here, to set the scene. The foundational model for magnetic sulfites requires separation of a sulfide melt from mafic or ultramafic magmas. In many cases, where the source of sulfur is external to magma and concentration of the sulfides into feeders, channels, or layers. The more dynamic the phases of magma and crustal interaction, the more likely the deposit will be a value. In many ways, this is one of the most quantitative ore deposit models we have. Given his unique experience, I asked Peter to provide his perspective on the model and the advancements over the last 20 to 30 years. - So as I've said, my view of the models of formation of nickel sulfide ore deposits have been heavily tainted by my experience as an exploration geologist, rather than as an academic. And so the things I might focus on as being pivotal, maybe different to the ones other people would select who are more concerned with understanding the physics and chemistry of the actual processes, I'm looking for the signals that, what can I use? And so that's really been, that's been the heart of me trying to understand these systems. I could list probably five things that have been really critical. I'm going to start off by the, you know, with the one that really, it's in the news everywhere at the moment. And that's the concept of a mineral system. An order deposit isn't just an order deposit. It's part of a bigger geological system. And the only way you understand the order deposit is if you understand rocks that contain the order deposit. A lot of my research started off with the container rocks without actually focusing necessarily on the ore bodies that happened at Sudbury and it happened at Morillst where I was driven by the interesting rocks. - You were, you were in the outside. - Yeah, yeah, I was in the outside, but I knew the systems were there. I just felt, hang on a minute. Well, do I want to just go and look at the mineralization? No, and I couldn't get to the mineralization as easily as I could get to the container rocks. And so that also helped things along. The actual, you know, the examples of how that worked out at Morillst really interesting, a series of basots, a new, and what at the time was a new analytical method all came together to provide an approach using chemist stratigraphy to understand how the rocks performed and then accidentally more than anything falling over the fact that a large part of the sequence had really low nickel copper cobalt platinum pladium and gold abundances far below what you'd expect in a basal. I kind of recognized that and with, you know, Tony, Tony was really, he was absolutely shocked by it. He thought it was incredibly significant. And I thought, yeah, it's pretty important. - Probably, probably, there were the ore deposits, I'm fairly sure. - Probably, me going, you know, I'm not thinking that as an explorationist, but once that nut was cracked though, and you realize the significance, then you look around the world and go, "Well, where else can I find rocks like this?" And Wes Greenland was a great place where the disco package had this signal in. And then I thought, "Well, it's sugary. Where does all that metal come from?" So I had to go and analyze the sugary, it knew it's complex and then go, it also-- - It's depleted as well. - Yeah, it's a signal. So it's really neat to be able to go around and actually to actually recognize the signal in multiple different locations. But it wouldn't be possible if you didn't have the heart of a mineral system in the root of it. - Right. - The second thing that fundamentally, what was pivotal to me really is big data. As an industry exploration geologist, you can have databases with hundreds of thousands of analyses and tens of thousands of drill holes. You can have three-dimensional models. You can fit everything in and understand what is irrelevant and what is important in the system. And you can build an understanding without that model you're lost. The downside of that is every deposit has such a giant database that you can get lost in data, totally lost in data, which is why I'm really heavily into data science and machine learning applications because I want to unpick all of these details and see what matters without having to do what I refer to a machine Peter going through all of the data myself. I want software to be able to do this one day. - So I think in economic geology, we don't even know yet what the impact of having all that data will be on our understanding of processes. - Yeah, so big data is really important. Analytical methods to me were the most fundamental thing. If the new technologies of ICP hadn't come along out, I hate to think where we would be. It really has revolutionized the understanding of nickel models to be able to do chemical stratigraphies through intrusions through all bodies and through the associated problems. - If we were still on the microprobe dialing at these analog dials that I remember at U of T. - Absolutely, yeah, knowing the stakeholders back on. - Yeah, all night long. - So I'm almost down my list now. I think the fourth one was structural geology and where I think nickel experts attended to put structural geology a bit to one side. It's not the heart of what they embrace. - I have this possibly false impression of nickel experts as all being petrologists. - Yeah. - It's all about the anorthocyte and the cumulets. That goes back to my early history in listening to lectures in 1981 from Tony. - Yeah, yeah, that's what I think you're right. I was fortunate in my career to work with a guy called Rogerio Monteiro to be open my eyes to what to look for in all bodies and the container rocks in terms of structure and the sorts of processes that control mineralization and it was fundamental in understanding the importance of an open space creative on cross linking faults, for example, interest in transcurrent faults or the effect of folding on the creation of space. All these things really important, I think, and have added enormously to not just understanding nickel systems, but lots of other opposite types as those types of structures are really important in things like ion oxide, copper gold, porphyry, you know. - Absolutely, yeah. - Critical. The final one on my hit list of model, you know, things that have developed which I think are really significant is the recognition of hydrothermal nickel and this is something that probably 10 years ago people would have been reluctant to believe that large quantities of metal could be concentrated in fluids and now we have great examples from Carriage S belt of Jaguar and GTN 34 as well as enterprise in the San Diego copper belt. Really interesting, opens the door to actually understanding nickel deposits in a totally different way. So kind of bridges a gap between magnetic and a hydrothermal systems, you know, in a structural context. - Right, you know, talk about mineral systems and it totally expands our perspective. - Right. - Yeah, and doubtedly how one might explore. - All those things that are close to my heart are as exploration tools as well as being important. It's fundamental basic sciences, critical, great geological mapping. The collection of high quality geoscience data is still the root of the whole growth of new models. Models required data and data requires a lot of effort. That's why being in industry is such a massive advantage in terms of the quantity of data. There are places I think where models will be improved into the future. I think ge analysis is continually methods are improving and the ability to handle smaller and smaller domains within minerals and then pick the details using multiple elements and even nice stroke ratios. It's unreal. A lot of people are running around doing nickel and copper isotopes these days on different systems. - What are they learning? Looking at rocks that show a ranging composition that are linked to what are recognized as processes and at the moment those processes are not recognized as processes that can create isotopic differences in the ratios of metals like nickel and copper. So they're trying to unpick what's causing that and what signal you'd be looking for. - So we see the differences and we know there's processes but we don't actually know what's causing what, yeah. - There are game changers that in the recent past during my career, things like electromagnetic methodologies and airborne gravity surveys had such an enormous wealth of data in terms of understanding the earth structure and understanding the container rock distribution and the all-body distribution. So it's a range of different technologies that help to resolve things at different levels. It's part of the, there's always a difficult thing. You can go with a very specific problem and try and solve the problem and you can also go and say, well, I have an analytical tool there which can really do something new and I'm going to find out whether or not differences exist in nature. And I think that's where the world is at in a lot of this at the moment rather than having cracked problems. So it's a geo-analysis thing to me, that's really me. Some of the things that really are interesting that are coming out of work that's been completed in the Norrop belt of West Greenland, the Grandville, the Fraser Range, are these high grades or deposits of nickel, things like Nova Bollinger. You know, they don't fit into quite the traditional view and the work that's been going on around the role of metamorphic processes in the formation of magnetic type sulfides, metamorphic, magnetic type sulfides is really important. It kind of also stretches to Thompson. I mean, the high grade Thompson was, wouldn't be there, but for really high pressure remobilization, high PT conditions, which were so critical in their formation. So this is all new and quite exciting and not yet entirely understood, I don't understand how the Thompson or bodies were formed yet. I wish I did, but there's a wealth of understanding to come from understanding plastic, the kinesis that sulfide from one location to another under high PT conditions. - It's easy to think that some of these mineral systems, like the magnetic sulfide one for me, is just ingrained in tight, but what you've just explained there is a whole raft of ideas and processes to be thought about and incorporated. - That's right. The sulfur sulfate control on precious metals. The old traditional view was, though all these metals are controlled by the different sulfide minerals and magnetic sulfate, whereas most of the PG's variations are in tellurized bifnasides, arsonides. There's something going on here that is very, very deep and very interesting. And around that is a whole question about why are some ore deposits rich in precious metals and others are not? There are just a few that really are high grade PG systems, like some of the sub-gray ore deposits. The vast majority are almost bereft of elements that to be quite frank based on traditional partitioning should be there. There's something we're missing in our models that are explaining those variations. And hey, I could probably go on with another 15 or 20. - With Peter's unusual career, before I let him sign off, I wanted to find out what parting words he has for early career geoscientists. - I would always encourage young geoscientists to go and contribute, take your contribution as a professional geoscientist of time and energy in educating and helping the world. Take it seriously. Don't just close your door on the university once you get your degree and forget about everything. You know, keep people engaged, keep projects going. That engagement, it's absolutely, it will reward you 10 times over. The other thing too, often you can get very caught up in a small world, your own world of your own expertise and microcosm of the bigger picture of a board deposit geology. It's like being in the mineral system, looking at the grain of calcopyrides and forgetting about everything else. I would recommend against that. I would recommend always look at your world in a bigger way. Don't get caught up in the little questions. And most importantly, don't get caught up in academic beckering and infighting on the world's importance of different models. Find the common ground and find the way forward. It's my recommendation. I've just seen this so many times that the models get compartmentalized to the point at which no one's listening to each other. And that's been something that I've hated. I'm quite happy to worry about how to thermal as well as magnetic processing and value enormously. The time I spent working with Ega Soutov, who was one of Koshinsky's students from the Russian Academy of Sciences. And he taught me a lot about how fluids might actually play a role in magnetic processes. You can have a really wild viewpoint and come up with some really interesting new models that you, if you have an open mind. Our next guest is this year's Lundgren Award winner of the SEG, and currently a research scientist at CSIRO in Western Australia. She's working with a team who are making new observations at the mass of neural score body with implications for mineralization and the permeant triassic extinction. - So my name is Mango Le Viache, what were the French accent? So how did I end up in WA? So I studied my studies back in France to center grads and everything, then moved to Finland and Sweden for masters, 'cause they were doing more exploration, focused masters over there. And then I think I just wasn't ready for industry or for work, and I was to keep up studying, keep on learning. And so that's when I decided to go for a PhD. Even though I thought when I was younger, there was nowhere where that would be smart enough to be a research scientist, but I realized after that, it's just more specialized, not smarter. And so I applied for PhD projects. Both, I think I looked for Canada and Australia, but Australia won because I had been in Finland and Sweden for two years and I was sick of the cold. So the sunshine won, and then I had two opportunities, one in Melbourne and one in Poets, and the sunshine won again. It came to WA to work with Marco Fjorentini and Steve Barnes on a project, "Uncomodated Hosted Systems." Just sounded really interesting, like talking about this old volcanic flows and the associated ore bodies and everything. And I had never worked on any of those systems before, and I was just like, "Well, that sounds cool." So that's how I got into it and then got stuck in there. - Yeah. - I think it is an area of our science that sort of grabs people and keeps them once you get into the intricacies of it and start to understand the processes. - Yeah, the more I work on them, the more I find them fascinating to just talking, thinking about these old volcanoes and the old lava flows, and it just grabs the imagination, I think. And then I just stayed in WA, kept on working with Steve on my medical intrusion hosted systems when I joined CSI Roe for my postdoc, and I just stayed on. And I'm still working a lot, actually, on my medical solidified systems, but over a whole range of different projects as a research scientist and with CSI Roe. - So the work with Steve is at the work on the risk that you've been doing? - Yes, some of it, yes. Well, actually, Steve's been involved in most of the work I've been doing at NERUS, definitely. But that's through my postdoc with Steve that I got introduced to NERUS. - Right, which is, you know, maybe you can tell people for those who don't know, a large. - Yeah, so it's probably the largest, or a buddy there, in terms of Nicole Copper PGE systems. It's located in Northern Siberia, in Russia. So it's in a bleep place. It's quite impressive when you had a chance to go there once, it's a very, very impressive place. The size of the orbite is, you don't realize it until, you start going underground and you take a shaft down and then once you're down there, you take a train and then once you've taken the train, you take a big four-wheel drive bus, that can take 12 people and you keep off driving and you still need orbite, this whole time, and you're like, okay, this is big. - That's big orbite, yeah. - That gives you, that certainly gives the perspective on it. So I've seen references in the literature to, or at least maybe on recent talks, to droplets and gas bubbles and things happening in this system that I certainly never learned about in the early 1980s from Tony Nuldret. Are you involved in that work? And can you tell us something about what you're learning? - Yes, definitely. So the visit to Norealist was probably my introduction to self-fied in bubbles and what we call drobbles, which is their close association between self-fied droplets and gas bubbles. And so Steve had been working with Jim Mungle previously, so that's a paper that they published in 2015 in nature where I think Jim Mungle and his team had been looking at a results of experiments, where they'd seen that association between self-fied droplets and gas bubbles in experiments. And so our eye was kind of started to actually look for these in the rocks, 'cause we'd send them in experiments with new-date, potentially existing in systems that we were looking at. And at Norealist, when we started looking at the rocks there and the jaw-cordering, our filter, that's when we really started seeing what we thought might actually be frozen drobbles in the rocks. - Drobbles is just such a great name. It feels like it should be a cartoon character, like, drobble drobbles is going in. Anyway. - But yeah, so then that's when we started looking for them. And so we took a whole lot of samples, came back to Perth and started looking at them in real detail. And with the observation we had did confirm that what we were seeing potentially were frozen drobbles in the rocks. - And it was just over an area of sampling that was widespread as a process that was happening everywhere in the system or were you in a focused area. - Sampling when you're doing a field trip is always quite tricky and Norealist being Norealist getting a range of samples for all the different OOTIs and it's quite complicated. - Yeah, to have really representative sampling, but when we first look at those, there was mainly in the PicroDollar right in the bottom half of the intrusion, so that what we call the Glaby Ours zones. But we did see them in all three Minerized Intrusions and Norealist town act in Karalak. That was omnipresent. And it's later on when we kept on doing work on Norealist with collaborators sending us samples, then we started seeing the evidence of gas bubbles, more widespread in the system, not just in those Glaby Ours, but also actually towards the top of the intrusions where you have the low sulfide, high PG Ours zones with a lot of chromates and so it's different, quite different textures you have out there. And we actually think that we've got evidence of presence of bubbles in there as well. - So yeah, how do you know there's bubbles? - Well, it's, yeah, all the shapes of what we see. So I guess, you know, the very rounded shapes and things like that. But then for the Glaby Ours, what told us that there were troubles is basically you have a hole in the cumulus framework. So if you've got the olivins or at Norealist it depends on the intrusions, that always olivins crystallizing first. But let's say it's olivin. You have those olivins that are the first one to crystallize. So you have your silicate males, you have your sulfide blabs that have already formed. You've already separated your sulfides. So you have those two melts together and then you start crystallizing olivins. The first mineral that you start to crystallize. And what we could see in our samples is that you had this framework of olivins, though it could see the sulfide blabs, but then around the sulfide blabs you had a hole in the framework that was now in fields by other minerals, the ones that crystallized later on, like a lot of parts in the plagiocles and a lot of very more hydrophases and phases that you would find in residual melts. So that we've crystallized really towards the end of the crystallization process and the intrusion. And so you can find those little sulfide blabs and then real hold in the crystal framework from the first crystals that form, right? And really just a composition in, like it's not a gas phase anymore of the states, all in fields by crystals now. - Right, I mean, you're not looking at fluid inclusions from whatever temperature magnets know. - No, it's really a textural interpretation, like meteorological and textural interpretation of what we see in the rocks. And that's why I think one of the technique that we used a lot that was kind of game changer for us was micro-exeriff mapping. That's when we started really using it to look at textures. So we use it a lot looking at sulfide brachias and on other projects, but that technique, which allows us to look at the whole drill core or even bigger sample. - You were talking several centimeters across or more. - Yeah, really big scale sample frame. - 15 to 20 centimeters long half-cut drill core, for example, and really mapping these things at a resolution of 30, 40 micron and getting these elemental maps. That really changed the way we saw things and we looked at textures and some of the troubles we were seeing, actually quite big. And if you do a thin section, you don't necessarily have the whole trouble in there. Sometimes you only have half of it. - Interesting. - Okay. - So I think micro-exeriff mapping with different scales is really something that helped us when studying these textures and studying the rocks, it really changed the way we looked at them. - So changing the scale of your observation, effectively, which is not always easy for us to do that. - It must be very big files though. - Huge, especially when you start going to the synchrotron, which we did quite a bit for the neural samples, just because they're fantastic drill cat. They give you the best images. - I think all my background for all my computers now are the beautiful elemental maps from the synchrotron. - So what's the implications of all that? So you're seeing what you think because there are gas bubbles and troubles and sulfide droplets. How are you getting at understanding the actual process that results in this kind of frozen and time texture? - Yeah, when we started looking at these, we started to train and understand, okay, so we've got bubbles, we've got droplets and bubbles associated together in magnetic intrusion ecosystem that have mineralization. What's the influence of the presence of the volatiles? What happens? Does it really play a big role or not in our mineralizing processes and so on? And so, I mean, the one of the first consequence of the presence of troubles that we thought of, that we published about in 2017, I think, now in PNAS, was really the potential link between the neural disk or bodies and the PT mass extinction event. And that was just simply because if you had a sulfide blade attached to a volatile, we thought that maybe that was fascinating the interaction between your sulfides that contain all the metals in those systems and the volatile that then get released by the volcanic systems, right? And so having this close association means that you can actually float your sulfides up and then as you float them up, you decompress and you de-gas and some of the metals that are in the sulfide blade go into the vapor phase and then get released into the atmosphere. And that would release a lot of nickel, for example, the the atmosphere. - Talk about the Permian triassic extinction, right? - Yes, that one still elaborate on PT, right? - Yeah, peroturistic mass extinction. Because the neural school body is formed exactly sequinously with that extinction event and that's linked with the large igneous province so the Siberian large igneous province. So we think that this potential association between gas bubbles and sulfide droplets would have happened over the whole system not just where you have the actual orbit is and then that would create a huge amount of metals being released in the atmosphere along with, you know, methane, a lot of whole lot of nasty gases but we think that nickel that was released at that time might have also played a role in the PT mass extinction, right? So there's a lot of gas potentially being emitted. Can we distinguish better areas or more prospective areas or it's just about the general process? So that's what we were wondering. Did the Voltaus have an impact on the actual mineralizing processes as well? And so in order to try and understand whether or not the presence of these Voltaus bodies in our magnetic system had an impact on just forming like the oil bodies we then went back to the lab. And that's worth that I've been doing a lot with Jedha Yakodov-Marnaciano who's a French research scientist working with a CNMS in Ovaleon. And she does experimental patrology. So high pressure, high temperature experiments. We started working with her because we wanted to recreate some of the things we were seeing in the logs in the lab. And she was on the Noreal's culture with us because she was also starting to get into the world of magnetic nickel sulfide systems. That's how the collaboration happened. And so we tried to a few years back now, we tried to recreate some of these drobbles in the lab. And what we were looking for is the potential impact of this association, spatial association between the sulfide blabs and the gas bubbles on sort of physical transport of your sulfides, maybe on sulfide coalescence, impact on metal transfer in the system, metal enrichment of your sulfide blab, all of these things. And so that's work that we're now, to its end of the revision. So hopefully we'll get out there real soon. But what we saw in the experimental work, so we did little decompression experiments. So have a little capsule, you put silicate melt in there. So well, we put silicate powder. You put it to really high temperatures. You put different amounts of all the towels in there to start with. Put it to high pressure, high temperature, melt everything. And then you slowly decompress it. And you have a look at before decompression and after decompression compare the results. And what we saw is that, first of all, the association between the sulfide droplets and the gas bubble is always attached to one another. 'Cause we did these experiments and we imaged them both using micro CT. So 3D imaging to really see those textures in the experimental work. And then we also did micro XRF Mac, which I was talking about. But this time, I'd really, really small resolution for really small samples. So that was at the different synchromes, one in New York and one in Melbourne. And what we saw is that association between the sulfides and the gas bubble helps the upward transport of your little sulfide bleb. But while it's moving upward, it actually correlates with other bubbles and other sulfides. And then once you've got multiple sulfide droplets attached to one bubble, they basically slide to one one another and the coalesce. - Okay, so that makes it easier. - And so you get bigger bubbles and bigger sulfides and it's kind of a, as you go up, the more you float up, the more that happens. And so if you always have a gas bubble that's big enough compared to the sulfide droplet that it just keeps on going like that. And so it kind of collects the tiny little sulfide droplets and forms bigger ones. And coalescence of sulfide's house is always a bit of a problem in this system because we're in very dynamic magnetic environment where if you have a solid, if you form a sulfide melt, you've got to break it up and you're going to form tiny little droplets. You're not going to actually form one big one that's going to stay stable. They're not going to stay stable in the magnetic, really dynamic environment that we're looking at. And so coalescing sulfide droplets actually a problem in the metarizing process for these systems. So that could be one of the favoring, one of the process that's happening and one of the factor that helps coalescence maybe the presence of gas bubbles. So that's one of the things that we observed in our experiments. - Right. - Really physically observed in 3D this process in action. - Yeah. - A lot of physical processes, a lot of processes that happen at like very different scales or at small scales, which then also occur over a very large scale. - Everything at no risk as well. I mean that one big, big thing in no risk, I think is the fact that it's intruding into these really unhydrot and colon organic rich sediments. And that's a huge impact on the actual presence above volatile phase in the systems. The intrusion that are hosted within unhydrot-rich layers and cold-rich layers or sediments to the layers that are written organic matter. And that's what that gender has been doing and she's been looking at really the assimilation of the country rock and how that plays a role in the chemistry of the magma. And that it had a huge impact and there's a lot of things that I think we still don't quite understand but if you assimilate a lot of anti-hides, a lot of it. So too, you're gonna increase the sulfur capacity of your melt. And so you're gonna be able to actually put a lot more sulfur in your maestic melt than you normally would because you're oxidizing your system at the same time. And so if let's say you've got your intrusion, you're first to do that, you'll increase the sulfur content of your melt. But then suddenly you start eroding or including organic rich matter in your system because you're arrived on a horizon that's now reached in cold, for example. And when you assimilate that into your magma, then you suddenly reduce your system and suddenly yourself was not having been being in the maest anymore and that's when you get a whole lot of sulfides. And so I think at Noreal, it's quite complex, but my ceiling and talking for myself is that it's no coincidence that these massive orbodies are forming where they are forming. And I definitely think that the assimilation of this country rock has a massive role in why we're forming such a huge orbodies. But you assimilate a whole lot of sulfur and then you suddenly reduce it and you get sulfides. You got so many rolled tiles in the system, I think it's like a perfect storm. To cap this episode off, we spoke to a keynote speaker for the early career Platinum Symposium coming up in May 2022, who is asking fundamental questions that may have implications for exploration and to hear about his mineral analysis work. - Yeah, so my name is Eduardo Mansur, 28 years old. I've studied geology in Brazil at the capital of Brazil, Brasilia, Universidade de Brasilia. It's where we're called in Portuguese. - The famous city that's laid out like an airplane. - Exactly, so yeah, Brasilia has the design of an airplane. I've studied in the right wing if we want to put it that way. So we have the university in the right wing of the plane. I did my bachelor's in geology there. And after at the end of my bachelor's, I worked a little bit with exploration and I got in touch with my supervisor of masters at the end of my undergraduate students, which is Cezan Feira Filho, a work of technical copper PGA in Brazil for then extensive work there. And then at the time he had this project to study what we call the "longer deposit". It's a PGA deposit in South America, where I did my project in collaboration with Valley in Brazil. The deposit is located there from some way know the Carajas mineral province. So it's been well known for the iron deposits and the IOC deposits. But I've studied one of the PGA deposits. It's a largest in South America so far. After that, I decided that I would pursue a little bit more into the academic side. So I wanted to keep into the magnetic sulfide word. So I contacted Sarajean Barnes, Chicoidemi in Canada. And I went to do my PhD there. At this stage, we decided to study some semi-metals, so Selenian, Tolurium, Arsenic, Bismuth, which we then call "taps", which letter is an abbreviation of one element. And we also did a lot of work with mineral chemistry, specifically in sulfide mineral chemistry. So the main interests were to try to see which processes we could try to trace back using either these elements in sulfides or in whole rock. That was the main idea of say, OK, how do different crystal contamination, evolution of the deposit, where this could lead us in terms of how could it be registered in composition of minerals? Right. So hang on a second. You went from Brazil to Chicoidemi. So what was that transition like to Quebec? Yeah. You learned about cold. Yeah, I discovered a cold existed, actually. Brazil is a very warm place. Not as the warmest in Brazil, but it's pretty warm. Actually, I must confess that I wanted to work to Sarah. I look at for the person and less for the plate. Right. So I just look at, OK, I want to add a lot of Sarah's work in her students. And I found it very interesting, especially the part of trace elements. So I contacted her. And I must say, I didn't really pay much attention to the climate or any other parameter. And still, it was minus 20, minus 30. So yeah, OK, maybe I should have considered. But anyways, I got adapted to it. It was fine. And it prepared me for the future, let's say. Excellent. It was all right. But I finished the PhD there. She could meet after four long winters. And started looking for a postdoc. I talked with the other Sarah there. And together with her, we got involved into a project, which is partially funded by St. Auguste, an Australian company working at the hydro termo nickel deposit in the same province, the Carajas mineral province. So we believe it's a nickel deposit, but it's linked to the IOCG system that we have in the province. So it's, let's say, a very atypical deposit that we have in the province. So the idea was it's a very messy deposit. We wanted to have some relatively quick insights about it. So can we try to apply what we learned from mineral chemistry into the magnetic deposit, into this deposit, and try to see how it compares, because after all, it's a nickel deposit. So how would it compare to the magnetic ones? So we did a bit of trace elements and sulfides, magnetite, appetite, trying to understand the genesis of the deposit compared to the chemistry of minerals from other magnetic deposits and other IOCG deposits in the province. After all, we believe it is connected to the IOCG system. So you help this in there. And after this project, I applied and got a job in Norway, which is where I am now. So I've moved to another cold place. I'm working at the Geological Survey, also planning to continue the work mainly with trace elements to understand different processes in our genesis that there will be the main idea. - Right. So keeping the same tools, but expanding the horizon. - Yeah, that was kind of the idea since the end of the doctorate to keep looking at the magnetic sulfides as well, but try to open it a bit more to different systems, which I believe ultimately can help us in understanding the magnetic systems and other ones. I mean, I don't see how we can hurt. If you just broaden a little bit your horizons, you should just help in the end. That's my way of saying it, actually. - So mineral chemistry is something that's been attempted for a long time in terms of understanding the origin of deposits. But I'm assuming in thinking, listening to you, and obviously you need to talk a little bit about the tools you use now, but that the way then which we can analyze minerals now is advanced to a point where we can see enough or more detail to actually start to distinguish different populations or different origins. - Sure. So there are a few things in there. Whenever we talk, I'm referring to, yeah, we are using mineral chemistry, starting to use mineral chemistry. I mean, we're not rediscovering the will. This had been used for a very long period of time. And the thing is that we can go back a little bit and you people have always used this. For instance, in the case of magnetic sulfides, a very simple example. You can look at elephants and see their necocontents. So you're going to say, and that will be basically major mineral elements with a micro probe, you'd be good to go. - Yeah. - So the thing is that when this first started, then people started using it, but we didn't have much access to micro probes all over the world in a very red way. But with time, this now it's, let's say, a tool that if you're in magnetic sulfides deposits, it's very trivial too that you could look at your, let's say, necocontent in elephants. And can I see any sort of sulfide segregation signal? I mean, are my elephants depleted in necocote because I separated and saturated and sulfide at some point? And these became depleted. That was one of the applications that we got. And it's very easy to do. Then we can advance a little bit in time and in the methods. And then we started getting into laser regulation. And then laser regulation, LAICPMS. We started to get many more elements. This means that we are coupling two equipments together and analysis, the LA part is a laser regulation. And the ICPMS is the detection. So you take a laser and you hit a given mineral. Let's say in a size of a 40 micron spot, 30 micron spot. So that spot is gone, is vaporized by the laser. And then you take this gas with your elements that were sampled by this laser. You transport into the ICPMS, the second part of the machine, which is going to ionize it. And then you're going to separate all your elements with one minute and a half per analysis. Let's say you can get, let's say, 25 elements down to a few ppb in terms of composition. So we got out of those only major elements, which is very nice, it was useful. But now the technology advances allow us to get this wide range of elements very quick and progressively cheaper. - So then the question would be, if this is useful in an exploration context, is it becoming more accessible to companies to actually get this kind of data? - Yeah, I honestly think so. I mean, because our role now is try to build the bases or say, okay, we can trace this kind of processes with a wide range of elements. - If there can be proven enough utility for it, right? - Exactly. - Yeah, exactly. - So can you give us an example of a case where you've been able to distinguish populations of sulfides that was useful? - I can give an example, which is not mine, but we have a very good friend who did a very nice work. His name is Charlie Duran. Charlie Duran, he was a work with Sarah, as well as she could meet with a postdoc. And his postdoc was in collaboration with the Geological Survey at Quebec. And they had these two samples from the Labrador Troph in Canada, where they collected several steel samples. From the steel samples, they made some heavy mineral separates. Found some sulfide grains and analyzed the sulfide grains with no context of texture, no context at all. They just picked sulfide grains and analyzed. They were mainly pyrite and chalepopyrite. And from the data, thousands of analysis, they saw that, okay, we got two populations of grains with distinct composition. For instance, pyrite grains. Some pyrite grains have typical hydrotermal compositions that were similar to those found in hydrotermal deposits. And some were typical of magnetic sulfide deposits. So typical of nickel copper, PGE deposits. They say, okay, where did the samples come from? They went back to their data, and they saw that the samples that had a magnetic signature retracing back with the glacier movements. They were able to say, oh, they all come from this when a specific region. Whereas the hydrotermal samples come from a different region. So now the thing is, this has to be tested somehow if there is interesting, but I guess that's a good place to start with if we want to move in this direction on the kind of study that could be done on ultimate application of this, what do we call indicator minerals? - Right, what it might be able to do for us. So when you're talking about seeing the differences be between the two. - Yeah, there'll be different ways to do in terms of the sulfides, the main elements that were different in this case, the show, the highest contracts. It's arsenic and simony, selenium. It's nothing extraordinary. So now we have a good, let's say, we know what a deposit looks like, at least in terms of trace elements and the deposits that have been found. You're not the advantage of the magnetic sulfides that they're fewer relative to other deposits. - Well, it's true. And the ones we know about tend to be large and productive. So what about the small and unproductive or sub-economic? - So to me, I think one good advance we could have is basically, okay, we know what a magnetic sulfide or an oxide from a magnetic deposit looks like. We know roughly what the same minerals look like from a hard-to-termal deposit. But the days mean that if I find some sulfide or any mineral from a till that has this composition, it comes from a deposit, likely not. So the thing that we have to understand is, okay, so maybe this chocopyrite or this pyrate that I found in a till sample has a composition or from a magnetic deposit. But if it would only be those tiny disseminated sulfides that we find here and there and they're associated with mayfic or traumatic intrusions, they would always be on till. And probably there would be much more abundant than the deposit, otherwise we'll find a deposit everywhere. So the next step in this would be, okay, can we differentiate from this blob of composition of what we lump all together as magnetic sulfides? How can we distinguish this comes from probably a deposit where this is a barren sulfide? So I guess that's where people are working on. One of the problems, let's say, when you start working with laser data and this stuff is that you generate a huge amount of data. I mean, it's fabulous to say, okay, we got this wide range of elements, it's very nice. But like, when you sit if the data is high, okay, so how can I make something of it? So you have this multivariate statistic analysis starting to be applied to the field. So these are the things I believe will bring us more advanced towards this. So I mean, more accessibility to the machines, wider data availability. And then I hope we can keep pushing in this direction, okay, compare the sub-economic occurrences to the economic ones, use multivariate statistical analysis that don't be what I believe we can make some improvements to that. - Yeah, hopefully it does have some applications and then the connection to industry is kept. - It's one tool of many others. So you won't like find the deposit because of indicator minerals only. I mean, there's no chance to me. It's that simple, you can't. But you can use this to support some more tools that you have. And ultimately, if this only leads us to help better understanding or forming processes, this is already a good thing. I believe, I mean, if we, by using mineral chemistry, trying to vector toward the deposit or aiming in that direction, we manage to understand how deposit forms. I mean, all these questions that we're asking can you differentiate better in rocks from a mineralized rocks? Maybe not, but to me, it's the only direction that you can push together. Maybe get something that will be interesting. It's not simple. And you won't vector the deposit or easy. But that's the kind of questions I believe you must ask to try to move it forward. - There are no quick fixes. - Yeah, absolutely. - Absolutely. - So you're obviously at the early part of your career. And it's been noted that a lot of the people in magnetic selfies, the well-known names are retiring. Where do you think you're headed in terms of your science? I hope that we will get more interdisciplinary. So we start to get like to open a little bit in order to better understand magnetic deposits. Maybe you don't have to work only with magnetic deposits. Maybe it will benefit a lot if you get a little bit out and see other communities and other kinds of discussion. I mean, we're talking about the Platinum Symposium. 2018, there was this Platinum Symposium in South Africa, great conference. Not a big conference, but you manage to know many people that you've only read the papers about and you manage to talk to all of them. - But at that point, I remember that we're having a discussion of the sizes of layered intrusions. People are having this argument of how big kind of like a magma chamber be. So how much magma could you have at once? And this obviously is very important for the understanding process of a magnetic so far. But I felt there was a bit of a disconnection of between what was being discussed on the side of people that were mainly trying to understand how layered intrusions form and the size of these intrusions and how the magma dynamics work. With people, I mean, can these things talk together? How do they talk together? I guess it's just an example. If we try to get out of only understanding one specific problem, then we understand. I mean, it's being said, okay, magma, the gas thing, it's very important. It's been known for many deposits and many stars. But when you start magma, the gas thing, you start forming bubbles. Can this have a role transporting so far liquid? Is it also something important? So fluid dynamics and transporting so far liquid, all this stuff, maybe the timing for forming this layered intrusions, so many. How long does it take to cool one of this magma batches? How big are they? How much of so far? What are the implications to that? So this very, as you say, consolidated models that have been created. So I wouldn't feel afraid that the field is disappearing because you have a lot of great researchers retiring, see more as an opportunity. They lay this knowledge, very great knowledge, bases that everyone have, very cool work. So let's just work from that and see what we do. And I think it's just an amazing opportunity, actually, to see, okay, to wonder what we will know in, let's say, 20 years from now, 30 years from now, that's what I would like, what actually I like thinking about. We really appreciate Peter Lifefoot, Margot Vallion, and Eduardo Mensoor for sharing your knowledge and ideas in this episode. Many thanks also to you, our listeners, for joining us. Please like, share, comment on our social media posts. We appreciate your support. I'm Ann Thompson, and I'll be back again next week with Bill Chavez and Paolo Basconcelos to explore the nature and importance of weathering. From understanding the rocks you were standing on, to enrichment of metal resources, don't forget to check out the Platinum Supposium, run by early career researchers for early career researchers, @flatsimposium 2022. This is season two of Discovery to Recovery, and all the episodes are available at sgtweb.org/podcasts, and most of the places you get your podcasts. Be sure to follow the SCG and Gold Spot on Twitter, LinkedIn, and their other social media channels to get notified about new releases. This episode was produced by your host, with support from our production team. I shall Ahmed, Halle Keeville, and Sam Weatherly. Our theme music is called "Fluence by East Winds." You can check them out at eastwinds.pancamp.com. Thank you for listening to this week's episode. Catch you next time.