26 March 2010

Accretionary Wedge # 23: What are you working on?

Posted by Jessica Ball

The latest installment of the Accretionary Wedge is being hosted by Ed at Geology Happens, and here’s the question of interest:

This AW is to share your latest discovery with all of us. Please let us in on your thoughts about your current work. What you are finding, what you are looking for. Any problems? Anything working out well?

My current work is a bit varied for a volcanologist, I’ll have to admit. I’m busy mapping features on the Santiaguito lava domes after our trip down there last month – lots of time on Arc, which for once is behaving itself. But I’m also working with the samples I collected from fumaroles on that trip, looking for alteration minerals. This is requiring me to learn quite a bit about clay minerals, and how to prepare samples and run them on an X-ray diffractometer (XRD). I haven’t done lab work since undergrad, and that was mineral separations for argon dating; clay prep is a bit easier, but takes longer, so I’ve only run one sample so far.

The results? Well, mostly the XRD seems to be picking up volcanic glass (from ash), because it’s showing the same pattern that you might get just from running the glass slide. A smear slide did produce some interesting peaks, but I haven’t had a chance to evaluate them yet (and unlike our clay mineralogist, I don’t have d-spacings memorized!) This is only one sample, however, and I have high hopes for the rest. If the XRD angle doesn’t work, I’ll probably be spending some time (and money) on the dentistry school’s scanning electron microscope (SEM), looking at particle morphology.

On the theoretical front, I’m getting ready to visit Los Alamos National Laboratory this summer, and learn how to use a finite element heat and mass transfer code called FEHM. The code is designed to model heat and fluid flow in hydrothermal systems – magmatic in particular – and I’m hoping to be able to apply it to modeling the hydrothermal system in a lava dome. Not Santiaguito – the domes there are too complex to model directly – but hopefully by the end of my research, I’ll have developed a new generic model that will help explain how water moves through lava domes. This is no small task, and the thought of learning both the code itself and the thermodynamics behind it is fairly daunting. My committee seems to think I can do it, though, and I trust them – but it’s going to be an enormous investment of time and effort. Then again, what PhD isn’t?

So that’s the skinny on the short and long term. This is the first real chance I’ve had to dig into some data, and exciting things are ahead!