Glaciovolcanics in Iceland, Carleton College and Keck Geology Consortium

Advisors: Meagen Pollock, Ben Edwards, Cam Davidson

Vesicle Distribution in Glaciovolcanic Pillow Lava from Undirhlíðar, Southwest Iceland

Keck Geology Consortium

Vesicle positions traced in an example pillow cross section

During my senior year at Carleton College, I had the great opportunity to participate in a Keck Geology Consortium project, which is designed to provide research experiences to undergraduate students from the 18 participating colleges and universities. I joined a project lead by Megan Pollock and Ben Edwards that involved two weeks of fieldwork in Iceland, two weeks of labwork at Wooster College, presenting posters at the GSA national fall meeting, completing a thesis in the following year, and finally presenting our final work at the Keck Symposium at Wesleyan University.

I studied vesicle distribution in subglacial pillow basalt. My research for Keck was incorporated my research into my senior thesis at Carleton College. My summer fieldwork in Iceland was followed by petrology and geochemistry lab work at the College of Wooster. I used Adobe Illustrator and ImageJ extensively for data processing and preparing figures.

Thesis abstract

Pillow lava is the most common lava morphology on Earth. It is found in high abundance in many environments, from the ocean floor to the surface of Mars. Because pillow lava forms during subaqueous eruptions, it is often inaccessible for study. Thus, being able to analyze pillow lava using visible physical characteristics without requiring samples could improve pillow lava research. This paper analyzes the distribution and emplacement mechanisms of vesicles in uniquely accessible pillow lavas found in Undirhlíðar Quarry. These pillows are the only lasting record of a preexisting englacial lake formed during a subglacial eruption, so understanding the details of their vesicles may provide new insights into the timing and nature of their emplacement. I propose that the type of vesicle distribution in a pillow cross section may be used to infer proximity to the source, the rate at which the pillow cooled, and eruption events during pillow emplacement. In this study, I define six types of vesicle distribution in pillow lava based on the presence of a vesiculated core, vesicles in the body, and a hollow pocket. Four pillow types were identified in the field. The observed pillow types all had vesiculated bodies but different cores. I propose that vesiculated cores are the result of rapid pressure changes, that nonvesiculated cores indicate slow cooling and proximity to the source, and that hollow pockets indicate that the source was cut off or diverted. Vesicle rings and cores may be indicative of different events, like magma pulses or sudden changes of pressure of the surrounding environment.

access full thesis here

access Keck short contribution here

Related presentations

Thompson, A. C., Orden, M., Lembo, C., Wallace, C., Kumpf, B., Heineman, R., Engen, C., Edwards, B. R., Pollock, M., and Kochtitzky, W., Physical Characteristics of Glaciovolcanic Pillow Lavas from Undirhlidar, SW Iceland. Poster session presented at: Geological Society of America; 2016 Sept 26; Denver, CO. abstract

Wallace, C., Kumpf, B., Heineman, R., Lembo, C., Orden, M., Thompson, A. C.; Engen, C., Kochtitzky, W., Pollock, M., Edwards., B. R., and Hiatt, A. Geochemical Constraints on the Magmatic System and Eruptive Environment of a Glaciovolcanic Tindar Ridge from Undirhlíðar, SW Iceland. Poster session presented at: Geological Society of America; 2016 Sept 26; Denver, CO. abstract

Heineman, R., Lembo, C., Engen, C., Kochtitzky, W., Wallace, C., Orden, M., Thompson, A. C., Kumpf, B., Edwards, B. R., and Pollock, M. New Insights on the Formation of Glaciovolcanic Tindar Ridges from Detailed mapping of Undirhlidar Ridge, SW Iceland. Poster session presented at: Geological Society of America; 2016 Sept 26; Denver, CO. abstract

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