Chantal Iosso '20
Summer Research with Jeff Rahl, funded by a Mellon Grant, Summer 2017
This summer, I spent 10 weeks working on a microstructural analysis of the Uppermost Unit of Crete, Greece, with Jeff Rahl in Crete and Lexington. Crete was formed by the accretion of a series of thrust nappes from the African Plate which actively subducts beneath it. I chose to focus my research on one of these nappes, the Uppermost Unit, which is a unit that represents the unsubducted Vardar Ocean lithosphere from the middle Jurassic that underwent low grade metamorphism in the upper Jurassic. It's located at the top of tectonostratigraphy in a few small outcroppings around central Crete. The lithology of the unit is extremely heterogenous; one rock type present is peridotite with varied levels of serpentinization. We spent most of the days in Crete driving from one outcropping to another, looking for relatively fresh peridotites that would have unaltered olivine-an endeavor that is more difficult than it sounds. In the evenings, we stayed at towns along the coast, enjoying beautiful sunsets over crystal-clear water and delicious Greek food. We also took two days off from work to enjoy the beaches of Santorini and the Acropolis of Athens.
Back in Lexington, I cut rock chips from our collected samples and we sent them off to Spectrum Petrographic to get polished. Upon their return, we polished them some more and then used electron backscatter diffraction (EBSD) and energy-dispersive X-ray spectroscopy (EDS) to analyze the thin sections. In the end, only one of my dozen samples is unserpentinized enough to have appreciable olivine, but many of the samples have interesting information to delve into. We used the EBSD data from the olivine-rich sample to determine olivine's crystallographic preferred orientation. The olivine in this sample appears to have a B-type fabric, which suggests that deformation of the uppermost unit occurred under high stress and low temperature conditions. This supports previous theories that the unit was emplaced on the island in the upper crust. Hopefully, I will be presenting my results at the GSA conference this fall.
This summer's research was an amazing experience for many reasons: the opportunity to experience the beauty and geologic complexity of Crete, do research as an undergraduate, gain familiarity with the geology department's analytical tools, and work with such an interesting, knowledgeable, and helpful mentor (thanks Jeff!).
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For other opportunities, view the Geology Department's Summer Research and Internships page
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