I’ve just come back from sampling various Caledonian rocks in Shetland for the start of my PhD. 10 days in that gorgeous little archipelago, which nestles quietly between the Atlantic and the North Sea.
One of the aims of the field trip was to collect samples for geochronological analysis from a little peninsula on Mainland Shetland called Hillswick. Mostly because there were reports in the early literature of massive garnets from there, and that’s one of the main focuses of my PhD. And with a geological map that looks like this, how could I refuse the challenge?
Myself and one of my supervisors, Anna, went there for just one afternoon initially. But surely one afternoon isn’t enough to sort out such a mess? Of course it’s not, but a few things clouded our judgement that day.
Firstly: the midges
Anyone who has ever done any living, walking, camping, working etc in Scotland at this time of year will be familiar with the Highland Midge. For those who haven’t, they look like this:
They are bastards. They’re small, swarmy, and like to eat poor unsuspecting geologists alive. I was clearly unimpressed by the little beasts in Hillswick, here’s an extract of my field notebook, complete with squashed midge (I draw you’re attention to the title of the page).
Secondly: Space Dementia
People all have different names for this, but Anna called it this, and it just stuck. I’m sure everyone has experienced it, but this was my Hillswick experience of it.
We had been rained on heavily, it was humid, and warm (for Shetland), and critically there was no wind. We had to dodge some rather fierce looking cows, and plough through a field full of wet knee-high grass. Half way through the field something snapped inside me.
In the rain, being eaten alive by midges, in knee-high grass to the sound of distant cows I just stood there and laughed. For 10 minutes.
Space dementia - it’s like cabin fever, but for geologists.
Thirdly: RiP hammer
Like my sanity, my trusty Estwing hammer didn’t make it out of that field alive. I realised when I got to the next outcrop and realised I needed something a little more delicate than the 14lbs sledgehammer we also had with us.
But I wasn’t going back to that field. Who knew what mental or physical torture would await me…
We found some OK samples, but nothing too spectacular.
A few moderately garnetiferous amphibolites (see above), but none of the massive garnets we’d been expected. So we went dejectedly home and made a rather large hole in a bottle of whisky.
A few days later, we’d recovered from the Hillswick trauma, and decided to give it another crack (now that the windspeed had increased somewhat).
We picked up another hammer, avoided the strange farm animals, defied vertigo on the sheer cliffs, and eventually found what we were looking for.
Beautiful, beautiful garnets! The geology of Hillswick is so bizarre that I have no idea what age these garnets will give. Who knows whether they’ll be 1.2 billion year old, or 430 million years? I guess I’ll find out.
But one thing’s for sure. I’m glad I went back, despite the stress.
My PhD is going to have a lot of this.
So I thought I’d share what isotope geochemistry is really like.
Further to your interview on 11 February, I am pleased to say we would like to offer you a NERC scholarship to study Matthew’s PhD project “ Geochronology of multiple orogenic events in a complex basement terrane, Shetland, Scotland ” . The studentship amount will approx. be £15, 700 per annum for maintenance and a fees waiver.”
FUCK! I’m so excited! I can’t believe it.
This is literally a dream come true.
I have an interview on the 18th.
This is making me so nervous it’s disgusting.
But also unbelievably thankful my university/department/professors don’t think I’m totally useless.
That’s right, a tectonic map of the northern Europe/America before the opening of the Atlantic.
Why did I waste valuable drinking time doing this? Well, firstly I had way too much to drink on friday night (damn Scots buying me whisky!) and secondly, look how close Shetland is to the Norwegian and East Greenland Caledonides!
It shows really well why Shetland is so important for reconstructing the final stages of the Caledonian Orogeny.
If we’re to find evidence of the Scandian (430Ma continent-continent collision, which some people think is when the Iapetus finally closed), the surely we’ll find it there…
Watch this space.
I’m the first to put my hand up and say that until very recently, I had a near crippling fear of maths.
But as a scientist, I needed to bite the bullet and learn my shit, because I don’t want to be one of ‘those’ geologists who can’t be taken seriously because they fail to grasp the basic principles of maths.
However I’ve been getting more and more irked by reading geochemistry papers where the authors are proposing trends in isotopes/chemistry that are actually just a function of pure good-old-fashioned mathematics!
A paper in which an un-named, but very eminent geochemist has shown a trend, which he suggests is a function of sediment being incorporated into the melt of a subduction related arc-lavas.
Seems reasonable, right?
I’m sure you’ll notice, as I did, that the denominator of the y-axis is the same as the x-axis.
So essentially, this is a graph of 1/x vs. X. Such as this examples I just made in Excel (Where X=n*2):
Wow, a hyperbola! What a surprise!
It’s not a geochemical insight if it’s just a function of the maths guys… Please think about what you’re doing before you do it.
Back in the lab after the xmas break.
Having to run my ion-exchange columns again because the samples still had potassium in them when we tried to run them on the multi-collector Mass Spectrometer.
On the plus side, my samples still gave really exciting ages that we are definitely going to publish!
(as a side note, I’ve recently noticed that this isotope geochemistry lark is rather a lot of waiting around. Until something finally does happen and you have to run around like a headless chicken for about an hour…)
Just made the Shetland coastline on Illustrator. Pretty impressive to say I’d never used it before today.
That coastline was a bitch…
That even though I know others are working on it, there really isn’t any ‘recent’ published work on the dating of Shetland’s (metamorphic) rocks. Which is amazing because they’re in a pretty much unique position with regards to their proximities to both the Scottish, and Scandinavian Caledonides.
Most of the work that’s been done on it is from at least 30-40 years ago, with techniques that have long-since been out dated (like K-Ar for example).
It’s just so awesome to know that I’m doing things that no-one has done before.
Of course it’s hard work but it’s also SO FUCKING AWESOME.
After over 20 samples of various rocks for my various projects, I’m (apparently) now trustworthy enough to be left alone to do the analyses. Which meant I was able to get a photo of the XRF for an update of Steph Does Science.
It’s awesome to be working on such an up-to-date piece of equipment! I now have trace element data for all of my Shetland samples, and that’s thrown up a few surprises. Particularly in regards to the Strontium values for some of them…. But I’m sure you all know that Sr is a bit of an untameable beast.
Now I have these data, however, I can choose the right ‘spike’ for the Mass Spec work on my mineral separate dissolutions. But more on that later.