This is geology B with Oliver stimple.
Since the first geological surveys of Southern Greenland in
the 19th and early 20th centuries, it has been
recognized that the region contains some remarkable igneous
rocks these include extraordinarily thick Dykes up
to 800 meters, thick and elliptical intrusions several
kilometers in size containing a profusion of exotic minerals in
the 1930s, this period of igneous.
Activity was christened the Gada period after the north are
Bishopric of God are established in the area in the 12th century.
In the 1970s, the rocks of the Garda period would dated using
uranium lead, radiometric dating and found to be between 1.1 and
1.3 billion years old. The dating also revealed that
most of the Rocks surrounding the thick Dykes and elliptical
intrusions of the Garda period is a giant.
Granite batholith, that is 1.8 to 1.9 billion years old.
The baffle if was in placed during a mountain building a And
accompanying the Assembly of the Palio proterozoic supercontinent
called Noona about 700 million years before the Garda rocks
were formed for a refresher on Noona and supercontinents.
In general. You can listen to David Evans in
an early episode of geology B. It was not until the 1950s that
geological studies of the area revealed just how exceptional
the god are rocks. Are one of the leading
researchers who brought this to light is Brian Upton.
Who was studied the Region's geology intensively, and spent
over 20 seasons in the field between 1957 and 2005.
In what follows Brian? Upton?
Discusses both types of God are intrusions the giant Dykes, and
the elliptical intrusions that Scott them.
He refers to the latter variously as alkaline complexes
and Central complexes. Brian Upton is Emeritus
professor of geology at the University of Edinburgh.
Brian Upton. Welcome to geology, B.
Thank you very much. I'm very happy to be with you.
What led you to the guard? Our region.
When you first arrived on the scene, in 1955 principal
motivation for this was partly for looking for more uranium,
but also Also looking for more crowl, light, for the aluminium
industry, in the course of this. We would also mapping
everything. Okay, went along.
What structural features did you find?
I was put on to some fascinating ground that had recently been
discovered by helicopter, reconnaissance work, which
included some very large, dikes. And some new Alpha line
complexes. I was delighted by that and it
was only in the fullness of time that I will.
It was possible whole system, the whole evolutionary process
that led to the extraordinary rocks.
So you found these enormously thick Dykes.
What do you think might have caused the dikes to be so very
thick. Well during the Precambrian, the
heat flow to the upper mantle and into the crust was
considerably greater than it was.
Subsequently were talking over a thousand million years ago.
And I think the energy was sufficient that when they
actually go and shoot Food around the world, goes some
other big ones being used. We see these in Canada, we've
seen Ethan Sweden extreme Southwest Australia and the
biggest of the laughs is the exam, Bob, we great dike which
is about 13 kilometers across and hundreds of kilometers long
but I didn't know how he said I was looking at it, we were might
relate to the elbows. And in fact it is chemically
rather different. It's unusual in this high
content of So called incompatible elements is an
alpha Li to break. Dyke was all of the others are,
by no means how Kelly, what can we infer by the tectonic context
that led to the formation of these huge?
Dikes in the guard, our Province, really nothing major
happened in that area for several hundred million years,
but there was a large Granite basileus that have been formed
after the last ocean closure there.
I'm the new activity ligado, activity.
Tended to be concentrated along the axis of this granite
basileus, and it looks with the center of the Basilisk.
Mechanically weak and had. Given way to allow Magnus to
come up to fractures a whole bunch of Dykes, which in places
Amalgamated to form one, which was as big as 800 meters, you
found Dykes. But you also found some large.
Mountain scale intrusions. Can we talk about those a bit?
We started getting these elliptical things which I will,
most certainly are feeding volcanoes comparable to those of
the East African Rift. But with a top two or three
kilometers missing because this whole region of the Guard, our
Province on the Rocks around it had been uplifted very, very
gently during the course of the thousand million years or so it
has never been folded. We'll be in badly altered in any
way. It'll be lifted up and in so
doing it. And being exposed to erosion
which had taken the skin off either.
Taken the top seal four kilometers off.
So we were looking modestly deep in the crust but not very deep,
but we're losing, the stuff is parts.
So these elliptical intrusive complexes are cyanides what our
sign i'ts. And what minerals do they
principally contain? Well, I have to say that the
most widespread and the important mineral on the whole
surface of our planet, are those of the group called feldspars,
which are aluminium silicate, but the aluminium silicate,
sheets are held together by other elements in particular by
calcium or by potassium or by sodium and those with potassium
and sodium are called Alkali feldspars.
And if you've got a rock, which is dominantly L4, I fell sparse
is called a siren, right? So, how did the rocks of these
Central complex has compared with those of the giant Dykes
once I was mostly interested in will sell one makeup right
across both of the sets of John, dikes and was a very much more
granitic type of rock, be emptied.
Dikes are all made of gabbros very much richer, and magnesium
and calcium, and iron and the essential.
Lex is so much richer and potassium and sodium, and
aluminium and silicone. So I think they were probably
products of crossed all melting it with probably remelting of
the old batholith, they g x, which were the source of these
things. But we've never really been able
to get a definitive answer on that.
You went back to study these rocks over 20 times over the
course of many decades. What made these rocks.
So special, They while remarkable for minerals
containing a whole variety of rare, metals are mentioned,
uranium zirconium under the elements that go with that like
niobium and hitch him. But also Elements which we know
now are extremely important in 21st century technology whether
we're talking about mobile phones or wind generators but
quite a lot of PSI nights around the world.
Do contain some exotic minerals containing rare elements.
Don't they Nothing nearly like some of those when we got our
problems and the one we were talking about specifically was
the Illinois outside complex, which again, cross Cuts these
John Dykes, I'm talking about, it's on the same Rift system,
the same linear system, but my feet are from the dikes and the
Illinois. Psyche itself is culminating all
of that activity. It's finished about 1104 million
years ago. And since then there's been
virtually never activity. Okay, so the intrusion that most
attracted your attention was called the Illinois, music,
intrusion. How did it get all that's
exotic? Minerals and rare elements.
Is it basically a result of extreme magma fractionation in a
magma chamber? Yes, I'm fractionation was
taking place. With unusual.
He's and Readiness because these dark rocks.
Have quite High floor, you contents to them.
And fluorine is an element. That makes a huge amount of
difference to The Melting of igneous rocks.
First of all, if it's sad, the melting points are lower than if
it's not. Secondly Glory moreover its I am
fluoride is extremely efficacious in, breaking down,
complicated silicate structures and in so doing it.
Makes the mag mostly liquid, the molten material very, very much
more fluid. It can flow very much more
greatly, not down to water or paraffin fluidity, but very much
more than most natural long-term Magma's because it was easy for
the English to move in. It, it means that again not
atoms, but ions can move quite long distances, unimpeded to
join up and form large crystals and Crystal fractionation
depends. Being able to remove crystals
are two ways of doing that. I've of the pistols are so dense
that when they form that, they sink to the bottom of the magma.
Chamber of that, they're in and leave of liquid above it
impoverished and that type. But the liquid above, it would
then be also enriched in those other materials that didn't make
it into the crystals that sank. Yes, for alternatively.
On this applies particularly to Illinois.
Exact sum Elementals are of low density, can actually float.
So, they go to the top of the pot, I used to like them.
This still talking to students having a bucket or water and
putting sound of fragments of cork into it.
And of course, all the sound settles on the bottom, 10
o'clock. Floats to the top obviously,
depleted the water in between, of both the lights and the
heaviest. So, a process, very simply like
that is involved in Crystal Cove.
Formation. And with the fluoride ions, as I
say, the molten rocks for Magma's are very, very much more
fluid through the crystals can't float, or see much more readily
than they can in most like most. So, does that mean that?
Because of this extreme Mobility, that's conferred by
the presence of the fluorine and the chlorine paps that you
essentially get much more extreme fractionation going on
crystal fractionation. Okay, Was all over the world,
all the time. But is simply is able to proceed
more effectively, more, readily faster and better in these
foreign Rich rocks and those that are deficient in Florian.
So, part of the fractionation process, you've just described
involves some elements. Forming crystals, readily, While
others do not and remain behind and become progressively.
More enriched, what determines whether an element remains
behind or is So called incompatible element
incompatible elements of those that just do not fit easily into
Crystal structures. So they tend to get left out.
But again, left of the wall flowers, around the dance hall.
If they pay small elements or atoms, lithium and beryllium are
very small and it's difficult for them to get taken into in
destructively tend to get leftover and concentrated them
late. Residuals of crystal.
Fractionation or if you're a very big fat around, you can't
get into any of these structures.
Your bust, so things like potassium barium, particularly
huge ones like uranium and thorium exclusion concentrated
in late stuff, and then some of them just have a pretty weird
bonding habits to put it that way and they get left out.
Gold will be one of those. Nobody wants it.
Sits on his head which is why you can go find native golden,
the rivers. You can't find most elements of
native elements that most of them combined.
But some like gold Platinum Mercury just get left out this
Friday all called incompatible with I still want to do.
This is a big like human relationships.
You're too fat. You're too small or your just
awkward, you get left on. And so, the last rocks to form,
then the ones that are most enriched in Developments.
Do we have any idea as to what percent of the original magma?
Body that might have represented a very, very, very small
percentage. You start off with a huge volume
of slightly enriched material. You take away all of the other
minerals, which are not, those of the enrichment, and the more
you take out the more you concentrate.
And so, we must be talking about a really large volume of
material. Would that originally have come
from the mantle, or from the deep crust, No, The Mantel
cross-boundary this comes from the mantle and we're talking
about processing of huge magma volumes which must be very many
cubic kilometers of magma down below.
Which are busy undergoing, Crystal fractionation, and then
the batches of the melts produced by just rise to the
surface and form. The things that we can see and
get out and collect from their lies.
So do you think that this mantle source of an enriched magma that
then wound up being fractionated to less than 1% to form the
final rocks that we see in these intrusive complexes doing.
That was already, then enriched in fluoride is And chlorine
ions, it was relatively impoverished in the mantle rocks
depth and then it gets more and more concentrated as Crystal.
Fractionation process has proceeded.
Are there any theories as to why some matter rocks?
Might at that time in the neoproterozoic 1.12?
1.2 billion years ago, have already been enriched in these
halogens. Why we got our problems in
particular was enriched. Is unknown, it's not just
fluorine. It's also Claudine and to a
lesser extent, its fellow elements bromine and iodine, but
the ones are particular interest of fluorine.
And then the next heaviest is for you in the other Malta as
crystallization of the sun. I just took place chlorine or
chloride ions became more and more concentrated and then
linked up with sodium and sodium silicate perform a minute.
Which was a low density three could float and it was not
acting the cell fragments of cork in the sand and cork
experiment. And instead of going down is so
teed up to the roof of whatever chamber there was there.
And in the when I was a kid, got one unit which is about 17
kilometers across, it's about 10 kilometers broad.
So that's 170 square kilometers. And then the thing is about five
or six. Five kilometers thick, so finish
up with an extraordinary concentration of fluorine or
sodium chloride Etc which is totally unique across the globe.
You mentioned that the God our Province contains several of
these elliptical intrusive complexes in addition to all the
Exotic minerals that we're going to talk a bit more about is ill,
Emmaus, a call. So the place with the greatest
concentration of fluorine, another extraordinary
concentration, not very far away for the place.
Hold it back towards, where the influence of my own Eleazar,
remarkable white mineral there and they used it.
I think for washing soda and various other things before it
was the sculpted. It was extremely useful in
extracting aluminium from aluminium or the rockhold
bauxite. And it's primarily, because
addition of fluoride to walks, I lowers the melting temperature
greatly, so it's a hugely cheaper extraction.
Assess the amount of energy requires, much less.
And in that particular case, it also turns the Melt into an
electrolytic solution you can post an electrical circuit and
you can separate the aluminium at one of the electrodes and
that is still the worldwide method of separating of oxide
giving throat was known from suddenly the 19th century in the
waves were using it and European explorers found this stuff.
From the also felt aluminium process important.
It was mined for the best part of a hundred years, but during
World War 2, when aluminium was critically needed particularly
for aircraft production, something like 12 million tons
of Corona. Light was wind, from ich, totems
sent to the United States for the war effort.
So, we've got this place called in ductility, which is
extraordinarily rich in fluorine.
The whole goddamn problems have got high Florian but it was
quite ridiculously highly concentrated.
Not just one fluoride mineral I've spoken of a highlight but
16 others. So got our problems have been
famous. If it was fighting each other
alone, but then we've got this other one I'm talking about him
outside and he comes back to the question, why?
You get these super high concentrations of the simple,
haylage of elements, fluorine chlorine bromine and iodine.
You, okay, well, concentrated why we still don't have an
answer. So in those two regions in the
mouse Arc and evicted are there. Lots of other exotic minerals
and other minerals that are only known there or which it is that
type location where they were first discovered it a church
quite a lot of the floor eyes. There will be tossed about
globally unique. Both igneous rocks and son.
I sung, granite's. You would be lucky to find the
perhaps a dozen different minerals and Iraq.
In the uml Zack, you've got 220 known different minerals.
So it's order of magnitude bigger.
It is a ridiculous. High concentration of extremely
exciting goodies. So, which is, why is a mouse
icon has become such a focus of international?
Interest. You could imagine every country
in the world with our technological basis is desperate
to get at it. I'm would suspect very strongly,
but Mr. Tongues Bid to Buy Greenland from Denmark was first
and foremost concentrated on Illinois.
Mouse icon. One or two others.
In the got our problems. That's extraordinary though.
So the variety of minerals stay in a piece of cyanide that
you'll find in this complex and their mouths.
Complex is literally over about 10 times.
The number that you would find in the next closest alkaline
intrusion or similar kind of plutonic Rock.
Yes, many of them were. Absolutely totally unique to
allows the mineral that they were most interested in before
uranium is, are an extraordinary mineral?
Because it's basically a silicate is God silicon and
oxygen but it also doubles up by being a phosphate and also it's
a silicone phosphate. Well, I've never ever heard of
any comparable mineral anywhere else from the steam stupid.
And it is, the students should be in the contains the
relatively High. Uranium, I want to come back to
the tectonics of the region and the history that we think must
have happened. So because you've got dikes and
you've got these intrusions, are we talking about an inferred
region of Continental rifting. It was an area of Continental
rifting about eleven hundred million years ago.
It's right now. Arrow.
It's only about 15 kilometers across.
So, we're talking about rifting that was going on about 1.1, 1.2
billion years ago. We're talking about a quarter of
the age of the Earth. Can we use this extraordinary
glimpse into an ancient Rift Zone 2 and 50 anything about how
the planet might have been different than or whether plate
tectonics was different. The plants are for about four
and a half thousand million years ago.
And there must have been extremely hot.
It's been using heat other since its floozy, he At the present
time but very, very, very slowly for the last few hundred million
years, but a thousand million years, it was still really quite
warm. And as I used to tell students
from the Precambrian, they just did things bigger and better
because they have more energy to drive things around.
So we're back when the Earth was not hot.
But a lot more Mount the thermal loss through the crust was a lot
more than it is the person time. And did that contribute to the
extraordinary thickness of these giant dikes and perhaps to the
extreme Mobility. Then of this magma body that led
to this extreme fractionation and illa ma sack.
Definitely. If you start looking at modern
geology real say from about 700 800 million years ago doesn't
sound very modern. But it is.
You're getting dikes formed all over the place, but I died like
20 meters across will be quite unusual.
Get dykes Approaching a kilometer on one is really very,
very rare. Indeed, it was just more energy
available to pull things apart and do cause damage from the has
been subsequently. One of the things you mentioned
when we spoke Ali was that these igneous rocks of the Guard, our
period appear to be in quite pristine condition.
So, before reliable radiometric, dating results became available,
did you conclude therefore that the Rocks were relatively young
geologically speaking? And we are in such beautiful
pristine condition. First of all these must be
perhaps about has always the organic rocks from the west of
Scotland. And they have Aegean region
which are about 20 million years or so old.
But certainly not Precambrian to say it's a bit of continental
crust that the gods forgot about, they don't lift it alone.
After the god or period. Some things did happen because
cream and split apart from Canada from Labrador.
Continental region. Containing the Gaga rocks was
elevated. Just very very, very gently and
slowly it was lifted up by magical hands from a few
kilometers down towards the surface and of course everything
on the surface, continually being rubbed away continually
name, sandpaper by wind and Raymond ratio period has been
rubbed away. Very effectively by ice but even
so we're talking about an area all over about 20000. 80's where
these god-awful knocks outcrop and it's all been recently.
Scoured hangover laughs, a million meals were served in the
ice ages, but it's been extremely gently treated.
It hasn't been folded, watery, fluid, so Pastor actually of
alteration and your minerals. So it is a very, very remarkable
example of apostle continent and I find that quite wonderful.
I want to end by asking you what it was like to do feel.
Work in Greenland starting in the 1950s.
Well, before any of today's tourist infrastructure and
mobile phone service was in place.
Well, first of all green was a very big place.
It's about 2,000 kilometers from top to bottom.
So if you cut it out on your own Globe, tastier, say the North
End over Scotland or the tail end and probably somewhere over
Iraq or Persia to lot of it. It has some enormous Coastline
thousands and thousands of kilometers of co-lead coast.
This is not going to get overcrowded.
What was it? Like, Well, there must be
something wrong with me but I love empty places, unspoiled
battling places and those are still working there.
Your form very, very close friendships will break loose
bonding all sorts of mates which last for decades.
I've worked all over the world but times I've spent in the
Arctic everywhere from Siberia to Canadian object.
I love the people. I meet are extremely interesting
people very resilient They would be living now.
People that don't know about hardships and can live very
simply. We had my radio in the
beginning. My mail I would be dumped by
those on the coast with a load of supplies and attend and we
would be told they'll be back in the 70 weeks time.
You look after him and he looks after you.
So the buddy system is critical. You need your mate on your mate,
knees, you so things don't fall you don't fall off.
After yourselves the best years of my life.
Brian Upton. Thank you very much.
Enjoy talking to you Oliver many.
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