To do list of a PhD student

– prepare a mindblowing talk for a conference (due in – 2 days);

– make a scientific poster on a project you have no data on (due in 1 day);

– (tomorrow) do some test experiments for the poster to hide the fact that you do not really have data;

– hunt for gem quality perfect crystals (to use for deformation-reaction experiments). This includes calling people in Mexico, stealing from teaching collections and getting in touch with Latvian mafia in Australia (this and next week);

– prepare for an intelligent conversation with a great scientist who is coming to give a talk on a relevant topic by reading 5 of his papers (today);

–  design an experimental apparatus (last week);

– make daily visits to the workshop which is constructing the apparatus until they can not bear the annoyment and finish it faster (following week);

– destroy some of your perfect crystals with the designed apparatus (following week);

– crush some alumina for high temperature-pressure experiments (following week);

– go back to the Stone Age [pun intended] and do hand-polishing of experimental samples, so they get finished sooner (following week);

– do geochemical and textural analysis on the polished samples (in 2 weeks);

– learn how to do chemical mass balance reactions for the paper in writing (following week);

– write a scientific paper (next 2 weeks);

– save the world.

Who needs a life if you have a PhD?

salt experiments

a) design for the experimental apparatus we will use for salt deformation – achieves stresses of 8 bar (idea by S. Piazolo); b) KBr single crystals for the deformation-reaction experiments

A Saturday afternoon

It’s good to have friends who keep a professional rock saw on their balcony. Fills up my weekends when the lab is closed.

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A meteorite week

Besides of my PhD studies I currently have a small tutoring load in an intro geology course for undergraduates. Last week it was all about meteorites. We simulated meteorite impacts and demonstrated fragments of different kinds of meteorites. This was the coolest sample in our collection:

pallasite

Pallasite. Very rare. Very beautiful. And very expensive.

These kinds of meteorites make up only about 1% of all the meteorite finds. They supposedly come from the core-mantle transition zone of outer space bodies. The green crystals are olivine embedded in a metallic iron-nickel matrix.

(+ one more thing on my “to buy list” after becoming rich – a pallasite necklace).

Every cloud has a silver lining

A meeting with my supervisor after the “unfortunate discovery” (see below):

– “Hmm…ehemm…, so, what exactly I am going to do during the New Zealand’s fieldwork?”
– “Shopping!”

An unfortunate discovery

The last 2 weeks were huge ups and downs in my academic life. I made my very first scientific discovery and I lost my main field area.

Recently I spent much time studying the thin sections from New Zealand, from the place where I have an upcoming fieldwork soon. I was especially looking on samples from shear zones (the sites of intense deformation in the Earth’s crust). I looked on the thin sections under a polarized light microscope and tried to understand how the rocks behave when they get deformed and how the presence of water affects their behavior during the deformation. After a while I started to notice some odd things there:

  • Firstly, the minerals in these shear zones got more mixed with increasing deformation. Normally in a highly strained rock I would expect the formation of metamorphic banding defined by layers of softer and harder minerals, as the pockets of soft minerals tend to interconnect during deformation and provide surfaces where most of the slip happens in the rock.
  • Secondly, the grain sizes in the center of shear zone where larger comparing to the less deformed rock on the margin of the shear zone. Normally deformation reduces the grain sizes in a rock.
  • Thirdly, the grains in the centre of the shear zone showed less deformation structures than at margins of the shear zone.

And then, all these new amphibole grains with their strange crystal faces! The shapes, the occurrence, the size seemed just wrong, wrong, wrong! So I took my samples and went to my supervisor for some enlightenment on the matter.

She told me to do a bit of electron microscopy to get a closer look on the microstructures and check the chemistry in the most suspicious samples. A day in a lab (in a very cold lab) and I got results suggesting that my shear zones contain bits of melt. It was an extremely exciting discovery because nobody of the previous workers has recognized a melt in these shear zones before. At this moment I felt super-cool about myself for picking this up. However my joy did not last long. Very soon my supervisors reminded that I am not supposed to study the role of melt in shear zones. I am supposed to study the role of water in shear zones. And easy as that, my field area got discarded. The melt in the shear zones means that the original structures are modified. It means that much evidence is probably erased. Eventually it makes the system so complicated that it is impossible to recognize the fundamental principles of the processes which I am interested in. A huge bummer for me.

After all I got a permission to tag along for the fieldwork in New Zealand anyway but it won’t be a fieldwork for my project.  And the melt discovery most likely will get handed over to somebody else to work with. As Heidi Klum once famously used to repeat: “One day you’re in. And the next day you’re out” (c)ProjectRunway.

Oh, well, I still have 3 years of my PhD to go. And this is just a beginning.

Some melt microstructures:

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Electron backscatter image showing melt microstructures (qtz – quartz, bt – biotite, amph – amphibole, plag – plagioclase). Electron microscopes does not use light therefore images are in a grayscale. In these kind of images the heaviest minerals appears to be brighter while the lightest minerals have a darker colour.

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A typical mineral assemblage crystallizing from a leucosome (plag + qtz + K-fsp). Small angle of the plagioclase crystal against quartz suggest the crystallization from melt. The electron image is colour-coded by the abundance of K, Si or Al.

A day in the lab

I had quite a lot of fun last week cutting my samples for thin-sections. Just imagine: a screaming saw going through the rock like butter, a diamond-coated blade sparkling against the strong quartzite, cold water splashing all over the face and dripping onto the shoes, a fearless girl daring her fingers for the cause of science… A theme for an action movie, isn’t it? Oh, just a regular day for a geologist.

A fully equipped lab geologist

A fully equipped lab geologist

Anyway, the rocks I sawed last week come from Australian and New Zealand’s shear zones which I will try to understand during the few following weeks. This time my task was to cut 2×3 cm large pieces out of them which we can send to a thin-section laboratory for further preparation. There they will be polished, glued to small slides of glass and grinded so thin that light can shine through (normally it is about 0.03 mm in thickness).

Samples ready to send out

Samples ready to send out

The fancy little things at the end we call “thin sections” and they are extremely useful for geologists. By using an optical geological microscope we can precisely determine the minerals in the rock, their characteristics and arrangement. That provides a huge amount of information about the Earth’s history. We can infer how chemical reactions occurred, what deformation mechanisms where acting and in what kind of processes the particular rock was formed.

By using the techniques of electron microscopy we can go even further, down to a nanometer scale, and determine a precise chemical composition of even tiny spots in the section, as well as to find out exact crystallographic structure, defects and mis-orientations of each grain in the rock sample.

Thin-sections

Thin-sections

It is funny how some years ago when I decided to be a geologist, I was looking on plate tectonics, large scale structural geology, determined if I will do something, I will do something big. And look where I ended up – doing microscopy. However this is not as contradictory to my megalomaniacal ambitions, as it may seem. When you think about it, everything what happens on large scale is eventually governed by these very subtle grain-scale processes. Therefore to understand a mountain belt you have to understand a thin-section.

Guess where I will spend the next three years!

So this is official now. After finishing my Master’s degree I left Europe and moved to this beautiful country to pursue a PhD. Who knows, maybe there will become a scientist out of me eventually.

The next three years I will be working to understand the interaction between 3 principal agents – fluid, deformation and chemical reactions – operating in deep crustal environments, in conditions you get beneath the mountain belts when two continents collide. The project includes fieldwork, microscopy, experiments, and probably a bit of numerical modelling (depending if I’ll wake up my sleeping maths-genius). Also it looks like I am going to move around a bit as we do not have all the advanced equipment for my experiments on the place.

So guess the country and the city I am in now! As a hint, there is a logo of my new university at the right side of this post.

The winner will receive a limited-edition calendar for year 2013 featuring a collection of the best of my geology fieldwork pictures.

Update: The challenge is finished. The winner is B. Nelson