28 May 2009

2009 AGU Joint Session in Toronto: Days 3 & 4

Posted by Jessica Ball

Having hit conference overload about halfway through the day on Tuesday, I neglected to blog about what I’d been seeing, so I’ll be combining two days. Tuesday was definitely talk day; I attended volcanology and kimberlite sesions in the morning and afternoon, in which I heard about:

  • How melt inclusions in olivines and glass from eruptive products on Procida Island, Italy could be used to trace the volatile evolution, and thus melt movements into/out of the island’s magmatic reservoir (Esposito et al.).
  • An interesting pyroclast from the Sept. 1997 Soufriere Hills dome collapse. The pyroclast contains shattered feldspar and quartz phenocrysts (with really cool little ‘pipes’ where melt inclusions erupted out of the phenocryst fragments). Ben Williamson suggests that the pyroclast may have started as an injection into the base of the lava dome, sat there for a bit crystallizing cristobalite (also present), and was then ejected in the dome collapse while still somewhat viscous.
  • Roger Mitchell and Steve Sparks (and a number of other folks) sparring over kimberlite origins and evolution (and even over whether some deposts are kimberlites). This was particularly amusing, because there was much implying that the volcanologists who were involving themselves in kimberlite geology didn’t know as much about the subject as the petrologists who’d been working on it, and vice versa. I get the feeling this has been going on for a while.
  • An example of a sub-glacier eruption in Iceland a few tens of thousands of years ago that created eruption ridges of pillow basalts, fissures similar to Hawaiian spatter ramparts on Kilauea, and possible sub-glacial ponding of water from the melted ice (which could have affected glacier dynamics).

My non-conference time was taken up by a visit to the St. Lawrence Market, which is in the Old Town portion of the city. I love these markets; I’ve been to the Reading Market in Philadelphia and a similar market in Quetzaltenango, Guatemala, and I’m always excited to see all the different fresh foods. In the St. Lawrence Market, I discovered custard tarts, a fantastic Portuguese dessert that seems to be pretty popular in Canada, as well as cheese curds (a favorite treat from my field work in Utah); I also got to peruse whole sides of beef, giant king crab legs and tiger shrimp, and quite possibly one of the best crepe combinations I’ve come across (strawberries, Nutella, and mozzerella). (Did I mention at some point that I thought I would lose weight at this conference? Scratch that.)

Wednesday was fairly relaxed – in the morning, I listened to a talk by Don Dingwell entitled “When melts start behaving like rocks (very bad things can happen)”, which focused on the brittle-ductile transition at magma/lava fragmentation. I’m not sure I totally agree with Dr. Dingwell that the “essence of eruption is decompression” – there are certainly other factors involved – but it’s an interesting point. I also listened to a talk about Mount St. Helens dome rock by Rosanna Smith, whose study results show that high-frequency earthquakes caused by brittle fracture of rocks is possible in the interior of lava domes, and a discussion of the effects of volcanic edifice collapse on hydrothermal systems and ore-grade mineralization.

It’s good to be back in Buffalo, even if it was a slow trip getting out of Toronto, and we had to stop at the border because my car was full of foreign people and still has VA plates. This is apparently a cause for alarm, despite the fact that it also has several decals that someone could use to figure out that I came from a different state than I now attend school in. (Mostly it was a cause for fingerprinting and for the Department of Homeland Security to charge my French passenger to take the electronic fingerprint scans. Talk about moneygrubbing!) I’m also convinced that DHS guards are chosen for their ability to look surly and hulking.

Photos to follow as soon as I can find the right camera cord…