mpollock July 2nd, 2009
Todd Finished his I.S. Research!!!! – Rob
Todd measuring the diameter of a pillow.
The Iceland crew taking meticulous notes.
Yes I did and it feels nice to say that I have my field work complete. Thanks to Meagen, Rob and Adam for all of their help! We had a good time in the quarries collecting samples and we even had some competetive racing.
Now its time to go to Blonduos to work on Rob’s and Adam’s projects. -Todd
mpollock June 30th, 2009
Today, we spent nearly all day mapping and sampling one pillow quarry. We found that the pillows are highly varied in size, shape, and orientation. Todd is interested in understanding the relationship between pillow morphology and the physical properties of the magma. He hypothesizes that magma viscosity plays a large role in controlling pillow size. To test his hypothesis, he and his trusty field assistants (Adam and Rob) measured the dimensions and orientations of several pillows. They also sampled the interior and glassy rinds so that Todd can analyze the geochemistry when we return to the States. Tomorrow = another day = another quarry.
Adam, Rob, and Todd working in the pillow quarry.
mpollock June 29th, 2009
Ben Edwards arrived from the States today. After a short morning of getting acclimated, he and the Wooster crew headed out to the field with our Icelandic colleagues, Steina and Hauker. We visited 3 quarries that expose the internal architecture of 2 different pillow ridges. Pillow ridges form during subglacial eruptions, where the the ice melts and the lava is quenched. Thanks to the heavy machinery, we are able to see natural cross sections of the ridges, and we’re observing a lot of unexpected details. Most quarries show nicely preserved pillows, with radial cross sections and glassy rinds. Vesicles appear in a variety of patterns, sometimes concentrated in the center of the pillow or in concentric zones around the center. Surprisingly, there are a lot of intrusions as well. We observed one of the best examples of a feeder dike in contact with its lava flow. There were also some irregular and sheet-like intrusions that stood out against the wall of pillows. Clearly, there are a lot of questions to be answered here. Todd is going to address some of those questions in his I.S.
Adam using a hand lens to identify phenocrysts.
Pillow lavas with a hammer for scale. Notice the radial joints. The pillows are surrounded by brown, altered glass.
Todd (on the right) is pointing to a light gray dike that intrudes through black, glassy, brecciated material and feeds an upper unit of gray pillows.