A day in the field

So, what have we actually been doing in the field for the last 2 months? Each workday begins by starting up a snowmobile with a broken choke switch, which requires two pairs of hands, a set of pliers, and some love (i.e. Graham hauling violently on manual-ignition chord). Once parked near our destination ridge or cliffs, we dismount and set out for our farthest destination on foot and work back to the machines. “Empty” backpacks (i.e. without samples, but laden with sledge hammers, chisels, first aid kit, water, spare cloths, crampons, ice axe, etc.) are never lightweight, but the crampons are invariably necessary to climb off the glacier or up a hardened snow slope. 
When it comes to approaching fresh outcrops of rock, each geologist has there own style; Sophie, for example, crouches to look for minerals in her magnifying hand lens, whereas Graham takes measurements with his Brunton compass. I generally prefer the more direct approach of obliterating the nearest piece of rock with a six-pound sledgehammer. After heated debate of the geologic characteristics of the rocks—orthognessic? poikioblastic? porphyroblastic? pseudomorphic?—we scribble in yellow notebooks. The detail and thoroughness (and accuracy?) of my notes scale with temperature (1+ page at 25 F, 3+ lines at 5 F, and 1 line at -10 F), but I reason that writing with frozen fingers will yield illegible results anyway… Before stumbling to the next cliff, we chisel away and pack grapefruit-sized samples for extracting zircon, monazite, titanite, or garnet. Each of these lucky samples will have a scenic journey to sunny California onboard a freighter before being bombarded with electron beams and blasted with lasers.

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In the lab!

site rencontre gratuit sarreguemines Sorry that it has been so long since our last post. We have all been very busy back here at UCSB, our home institution. The field work in Antarctica that you followed along with is only one aspect of this project. Now it’s time for the “science-y” stuff. We have been organizing our samples and preparing them for dating and geochemistry.

http://www.homesap.fr/43091-dtf40181-demain-nous-appartient-telecharger.html Here’s Jason Schmidt, a research assistant working with us this summer, helping archive our samples in the dingy basement of our Earth Science department. We start with whole-rocks collected in the field and try to extract accessory minerals that are useful for dating and geochemistry. We crush the rocks using the disk mill you see below and then send the material down the water table (basically a glorified gold pan). This sorts the material based on grain size and grain density.

Next we use special chemicals to further separate the material based on density. Here I (Graham) am working in the fume hood, isolating dense minerals such as zircon, monazite, titanite, and garnet.

We take the most dense fraction from the “heavy liquids” step, and separate different minerals based on their magnetic properties. We use this funny looking contraption, the Frantz isodynamic separator. After this step, we hopefully have nearly pure separates containing only the accessory minerals that we are interested in.

 It’s time to image our samples before analyzing them on the mass-spectrometers. We take cathodoluminescence images using a scanning election microscope.

Finally! It’s time to get some data! The real interesting stuff happens in our plasma-source mass spectrometer lab. We have two lasers and two inductively coupled plasma- mass spectrometers that enable us to measure a wide range of isotopes as well as the concentration of trace elements at several ppm precision!

More to come on the lab work this summer… Stay tuned for updates on the upcoming field season as well!

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