Polar Podcasts

09: Kent Brooks: Earliest drilling of the remarkable Skaergaard layered intrusion

August 25, 2020 Julie Hollis Season 1 Episode 9
Polar Podcasts
09: Kent Brooks: Earliest drilling of the remarkable Skaergaard layered intrusion
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Polar Podcasts
09: Kent Brooks: Earliest drilling of the remarkable Skaergaard layered intrusion
Aug 25, 2020 Season 1 Episode 9
Julie Hollis

In this episode, we hear more from Kent Brooks – Emeritus Professor at the Geological Museum in Copenhagen – about the Skaergaard Intrusion, which he first encountered on a geological expedition in 1966, and which was to become the focus of his long career working in east Greenland. About his move away from Oxford to Copenhagen, forays into studying the unique geology of south Greenland, and being drawn back to east Greenland where his research interests would be firmly rooted for the decades ahead.

Show Notes Transcript

In this episode, we hear more from Kent Brooks – Emeritus Professor at the Geological Museum in Copenhagen – about the Skaergaard Intrusion, which he first encountered on a geological expedition in 1966, and which was to become the focus of his long career working in east Greenland. About his move away from Oxford to Copenhagen, forays into studying the unique geology of south Greenland, and being drawn back to east Greenland where his research interests would be firmly rooted for the decades ahead.

Transcript

09: Kent Brooks – Earliest drilling of the remarkable Skaergaard layered intrusion

Based on interviews held on January 9–10, 2020 in Kendal, England

Note: Polar Podcasts are designed to be heard. If you are able, please listen to the audio, which includes emotion and emphasis that is not evident in the transcript.

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Kent 0:02

We’d acquired all these, all these drill cores at great expense but the could never find anybody who was interested in working on it. If they’d worked on it they might have, they might have discovered platinum, palladium and gold and stuff in these cores, but they didn’t.

Julie 0:16

Welcome to Polar Podcasts, where you’ll hear stories from geologists who’ve spent their careers, their lives, exploring and studying the remarkable and remote geology of Greenland. Why did they become fascinated with Greenland? What were the problems and the discoveries that drove them? And what was it like working in these remote places, where few people venture, even now? I’m Julie Hollis.

In this episode, we hear more from Kent Brooks – Emeritus Professor at the Geological Museum in Copenhagen – about the Skaergaard Intrusion, which he first encountered on a geological expedition in 1966, and which was to become the focus of his long career working in east Greenland. About his move away from Oxford to Copenhagen, forays into studying the unique geology of south Greenland, and being drawn back to east Greenland where his research interests would be firmly rooted for the decades ahead.

Kent 1:18

The er, the Skærgaard Intrusion in east Greenland, it belongs to a class of igneous rocks known as layered igneous intrusions, where er basaltic magma has intruded the earth’s crust and solidified in so-called magma chambers. Er, in doing this it er, undergoes differentiation. That is the high temperature minerals crystallise first and they er, separate out, leaving a liquid behind which is a different composition, a liquid or melt behind, which is a different composition. And in this way it is thought that the er, the er spectrum of various igneous rocks has largely been formed. And so a study of layered intrusions will er show the processes which take place in silicate magmas, leading to the various igneous rocks which we have at the present time.

As anyone can imagine it’s extremely difficult studying this, this business because magmas come out of the earth’s surface as lava flows and they’re easy enough to study. But if they stop in the Earth’s crust, several kilometres down in the Earth’s crust and, and differentiate there, they’re virtually impossible to study in-situ. You can only study it when the er magma chamber has cooled, been uplifted and eroded away and exposed on the surface.

Now in 1931, or 1930, Wager found the er, the Skærgaard Intrusion, Kangerlussuaq, which lies four hundred kilometres north of Tasilaq in East Greenland.

Julie 2:52

Lawrence Wager was professor at Oxford in his later years and Kent's supervisor.

Kent 2:58

He was part of the er, the British Arctic Air Route Expedition, which had their base camp at er, Supertoq, to the west of Sermilik fjord. This was the first, the first er expedition to Greenland which made use of aircraft. They had two Gypsy Moths and they took spectacular air photographs of er, large areas of unknown East Greenland including the basalts of the Blosseville coast.

They er, sailed up in an expedition ship to Kangerlussuaq and Wager discovered this intrusion, which previously had thought to be made of sandstone. He identified as being layered gabbro, which er, the layering, when seen from a distance, looked like a sedimentary rock and the brownish colour looked like sandstone. The Skærgaard gabbros are brownish, rusty coloured rocks because they have a high iron content. And Wager recognized that the er, the Skærgaard Intrusion would be an excellent place to study the processes going on within the Earth’s crust as magmas differentiate. And he er organized an expedition in er 1935 to 36, an overwintering expedition, which he crammed into a, a very active life of becoming, becoming er a professor at Durham, first at Reading, and then at Durham, subsequently at Oxford. Er and an attempt to climb Everest, where he got to be the highest, the highest mountaineer in the world in 1933 I think, 1934 maybe. And he sailed with Einar Mikkelsen down the east Greenland coast in 1933. Er, so they overwintered in Kangerlussuaq, not only working on the Skærgaard Intrusion but er, doing a large regional study as well and covering, covering huge areas of country by dog sledge. They um overwintered there along with a family from Ammassilik who er, hunted seals for them. So they lived mainly off the land. Yeah.

They er, Wager and Deer published their work on the Skærgaard Intrusion in 1939. Although the war, the war, the war had broken out at this time, it immediately became er required reading for just about every geologist in the world because it er, it showed clearly the sort of processes that had been er, prognosticated by Norman Bowen using experimental techniques on silicate melts. The er, they returned to the Skærgaard Intrusion again in 1953 to er, augment the samples they had and do further mapping, and working on several of the intrusions in the neighbourhood. At this time they er, not only er, the emphasis was on er looking at the processes of which differentiation had taken place, but also it was directed to showing, showing the behavior of many obscure chemical elements in er differentiating magmas. How, how do, how do elements like zirconium and uranium, and strontium and rubidium behave when er basaltic magma differentiates?

Kent 6:17

The study of layered intrusions not only tells us how basaltic magmas behave on Earth, it tells us how er, how the differentiation took place in the, the planetary bodies of the solar system so that er, different types of meteorites can be explained by similar processes. Also, the er generation of important economic deposits of minerals can be er, can be generated by, by the differentiation processes. For example, the er, the er group of ore deposits known as orthomag, orthomagmatic ore deposits, which are closely related to igneous rocks and these include minerals such as er nickel, platinum, copper, and several others. For example, the world’s largest platinum deposit is found in the Bushfeld Intrusion of South Africa. Er, which is an immense layered intrusion about the size of Scotland. And er, the world’s largest nickel deposits are found in the Sudbury Complex of er Ontario, which is also a layered intrusion. 

Wager had been at the er, some, some geological meeting in California and he’d heard about the Moho project, which was a project in those days to use a barge to drill, drill through the ocean crust into the mantle. And it never came off because they didn’t get the funding for it. But it aroused Wager’s interest in er, maybe drilling the Skærgaard Intrusion er using, using the same barge, which would been towed into Uttendal Sund and drill, drill there. But that was quickly, quickly, quickly disabused of that idea because er, the, the barge wasn’t certified to go into ice-filled waters. So they couldn’t, they take the barge to the Arctic. But it did spark off the idea to drill the Skærgaard Intrusion. And so they hired the Canadian firm Longyear er, to, to do diamond drilling there. And they hired a ship from, from Ålesund, a sealing vessel from Ålesund called Polaric to transport the expedition there. Polaric, Polaric came to King’s Lynn, which is the nearest port to er, to Cambridge. And er took the expedition on board there.

In the meantime, however, Wager had died and so the expedition was now run by Deer. And Deer didn’t have the same enthusiasm, I feel, as Wager would have had. Wager actually er, actually the, the preceding November he went to London to er, to visit hi, his er photographer, to buy a new camera. I mean, he was, he was incredibly old fashioned was Wager. He couldn’t, couldn’t go down to Boots and buy a camera from Boots. He had to go to some fancy photographer in the West End of London and buy, a buy a specially, specially recommended Leica. Anyhow he’d bought this, bought this Leica from the shop in London and er went out on to Piccadilly and collapsed. And he’d had a heart attack and died there on the spot. So he never took part in the expedition. It was run by, run by Deer and it came to be called the Cambridge Expedition, which, which rather irritated me.

Kent 9:33

Anyhow we er, this expedition was in several parts. It was er, one, one part was, one, one group were due to do the er, do the drilling on Skærgaard and also to collect samples of Skærgaard gabbros with the idea of studying them for sedimentary features. Another party were er led by Peter Brown, at that time a professor at er, the University of Sheffield, would er go to the Kiarliip area, which at that time was a very, was unknown, completely unknown. It’s an area to the er, about two hundred kilometres south of Kangerlussuaq. And there’s an abundance of er, various sorts of Tertiary intrusions there. 

And er, then after that they would go and study the Kap Edward Holm Intrusion on the opposite side of Kangerlussuaq, which in the, the days when Wager and Deer overwintered in Kangerlussuaq er, Deer had taken an interest in the Kap Edward Holm Intrusion. It’s a very much larger gabbroic complex than Skærgaard, perhaps three, three of four times the size. And er, is a product of multiple intrusions of basaltic magma. So they would, they would study that.

Curiously enough, Peter Brown had er, was also an, an influence on me in doing geology because he’d been my next door neighbor during World War Two. And at that time he was er, he was I think he was er in the order of fifteen years old. I was probably, probably four. But he and his brother had set up in his attic a, what do you call it, a display of the Desert War where they’d er, sprinkled sand all over the floor and made sand dunes with it. They had little tanks and things going through it. And he used to invite me in to see that. Anyhow, when, when I was, when I was leaving school, I er, thought I’d contact Peter and I’d ask him what, what, what I should do. I was thinking of doing geology, I told him. He said, “Oh, don’t do geology,” he said, “there’s no future in that.” Er because this was at the time of course when the British Empire was collapsing and all the, all the geological surveys around the place in Africa and that were being, the geologists were being fired. Peter himself had been a geologist in the, in the Tanganyika survey. So he er, he was familiar with that. Anyhow, he said, “If you decide to ignore me,” he said, “the best place to go is to Manchester.” Of course he would say that because that’s where he’d gone been. So anyhow I went to, I went to Manchester to read geology there.

Kent 12:06

I’ll get back to the expedition and er, drilling Skærgaard. Well we drilled, we drilled the er, drilled the er the lower zone of Skærgaard in an attempt to get to the hidden zone. And after about, I think er, I don’t remember what it was, five hundred metres I think, the drill showed signs of er leaving the intrusion altogether. Well, the drill was going out of the intrusion so Deer decided to drill somewhere else.

So we moved the drill rig with great difficulty. We had to build a raft of bits of old, old telegraph poles and stuff from the demolished American World War Two meteorological base. We had to build a raft with er telegraph, telegraph poles and oil drums and float, float the rig down Uttendal Sund. And then winch, winch it onshore there and drill a, drill a new hole at the foot Uttendal Sund, at the foot of er, Forbindelses Glacier. Well, that’s all very well. What we didn’t realise at the time and what we found out later on was that we were drilling through er, through a particularly exciting part of the stratigraphy of Skærgaard with there’s a precious, precious metal concentration  but, but er we had the diamond, diamond core samples of that. But for some reason nobody showed any interest in working on this stuff. We’d acquired all this, all this drill core at great expense but you could never find anybody who was interested in working on it. So it languished in the, in the store in Cambridge for many years. If they’d worked on it they might’ve, they might’ve discovered platinum, palladium and gold and stuff in these cores. But they didn’t. That was to be er, that was to be, that was to be done by, by er Platinova many years, many years in the future.

This was 1966.

Julie 13:55

But returning to Oxford, Kent found that he had to deal with a new professor.

Kent 14:00

And er, I didn’t see eye to eye with the new professor and thought I’d, thought I’d, I’d move somewhere else. I was only on a limited contract anyhow, three year contract with the department. It wasn’t sure it was going to be, going to be extended, when, when the time [came]. Especially now that I’d gone at loggerheads with the professor. So I happened to be at the Geological Society in London one day and in the gentleman’s toilet I ran into er Drever from St Andrews. And he said, “Have you heard they’ve got a job, a job for somebody like you in Copenhagen?” And I said, “No, I hadn’t heard that.” And he said, “Well get in touch with Professor so-and-so in Copenhagen.” And er, that’s what I did. And I went over to Copenhagen and had an interview there and they, they er decided to hire me.

When I came back to Oxford, I er, had an altercation with the professor there and he said, “If you don’t like it here Kent, you could get a job somewhere else.” And I said, “Well that’s exactly what I’m doing and I’ll tender my resignation now.” And he said, “You’re not serious are you? People don’t leave Oxford when they have a job in Oxford.” And I said, “Well here’s one person who is going to leave Oxford,” which I did.

Well when I got to Copenhagen, I er, Professor of the er, Petrologisk Institut was er Henning Sørensen. And he’d for many years on the Ilimaussaq Intrusion in the neighbourhood of Narsaq.

Julie 15:24

In South Greenland.

Kent 15:26

And er, the whole institute was geared up to working on Ilimaussaq, which is an incredibly interesting intrusion. But it also has the disadvantage that it’s incredibly unusual. So whatever you find out about Ilimaussaq doesn’t have any, any real global consequences. It’s just er, it just applies to a, a very restricted group of rocks known as the agpaitic rocks. Well er, he had naturally assumed that I would take part in this, this summer jamboree up there. And er, so I worked, worked on what’s called the kakortokites, the lowest, the lowest rocks within the intrusion. And they’re strongly layered. If, if you like to look at it that way it’s like a sort of a, a sort of an exotic type of Skærgaard, layered igneous rocks. But in this case they’re highly alkaline and highly evolved and they contain the rare mineral, what’s otherwise the rare mineral eudialyte, a rock-forming mineral. Anyhow, I decided to work on the, on the kakortokites. Henning thought this was a good idea. And I had a, I had an assistant called Henning Bose, who to my great chagrin never finished his degree. He er became a perpetual student and then a perpetual advisor to mineral, mineral companies prospecting in the area. Every, every, every, every geologist who’s worked in the area knows Henning Bose. And every prospecting company relied on his expertise to help around.

Well my first idea was you look at all these, all these layers in the kakortokites, it looks like a multi-layered cake with, with er layers that consist of black at the bottom, then a, then a red layer, then a white layer. So it looks like a sort of er Battenberg cake. Er but like many of these layers, I thought the first thing to was to map the stratigraphy of it

Julie 17:20

The relative position of the layers, one above the other.

Kent 17:23

We gave, gave each layer a, a number and we collected a sample, a series of samples through. And that we did, thirty three layers I think. And so we started off at layer zero, which was somewhere in the middle and we went down to minus numbers and then up to plus numbers. And we had this er, we had had this collection of rocks which Henning Bose was supposed to work on. But he never did because he was most interested in going to Greenland and er, every year, every year when he’d been in, been in the field, he came back and he spent er, spent the time between coming home in September and Christmas tidying, tidying up his results, writing his field note books and various things. And then er, when I expected he’d get on with doing the work in January, he’d start preparing the next year’s field work. And this more or less went on for fifty years I guess. Or forty years maybe.

Anyhow, I spent two years on this project at Ilimaussaq. But it wasn’t really my thing because the er, they, they didn’t really seem to be going anywhere. They went up there every year and they did various things with the Atomic Energy Commission and looked at, looked at various, various outcrops that were mystifying. And they’d look at the outcrop and say ‘isn’t this mystifying’ and then they’d not do anything about it and come back next year and say, ‘what a mystifying outcrop’. I mean it was all very well. It kept the institute busy and many students graduated on that. Er, some, some of them, some of them did very good, did very good work in fact and went on to er shining careers. People like Agnete Steenfelt and er Lotte Melchior Larsen. But er it might it have been a good project for them but it certainly wasn’t the sort of things that I wanted.

So my interest started to er, started to return to east Greenland. And er, I thought that we, it would be very promising to look at the, look at the um igneous around Kangerlussuaq. Wager had done a wonderful job in his time. He’d mapped, effectively mapped a huge area of country extending from er, well south of Amassilik, where the er British Arctic Air Route had its, had its base to er, essentially up to Scoresbysund. An area of country that must be in excess of er, well I don’t know, probably in excess of seventy thousand square kilometres. And he’d done, done all of this from the deck of a ship and er, by walking around various places. So Wager did a tremendous job there. But quite naturally, there was a lot of stuff he hadn’t seen and I decided it was time to start er, start tidying up the loose ends there, which is what we did. But I came into it, not as a university project, because I’d just decided that an area I’d like to work in. And it came to my attention that the Nordic Mining Company had taken a concession there. And so I descended on the Northern Mining Company to, to push my case for being one of the prospectors. 

Julie 20:19

I’m Julie Hollis and you’ve been listening to Polar Podcasts.

Julie 20:30

In the next episode, we hear more from emeritus senior scientist Niels Henriksen about his years spent spent mapping the Caledonian Fold Belt in northeast Greenland.