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2020 Field Studies, Section 2

Oregon’s youngest obsidian lava flow at Newberry Volcano. This flow is ~1,300 years old with a spatial extent of ~1 square mile.

GEOL-406 Field Studies in Volcanology and Paleoclimate (CRN 41967) 4 credits  Instructors: James Watkins and Meredith Townsend.  Graded for Majors; P/NP optional for all other students.  $700 course fee (in addition to the $100 acceptance fee paid to hold your space in the course) and usual tuition and UO fees.

This section consists of three projects. The first two projects will be carried out in the Oregon Basin-and-Range, where students will examine relationships between volcanism tectonics in the Four Craters Lava Field, and how a nearby fault-bounded alkaline lake has changed over the past 10,000 years. The third project will be carried out at Newberry Volcano.

Close-up view of the base of the explosive pumice deposits.

The Four Craters Lava Field is a basaltic lava field that overlaps and is cross-cut by normal faults. On top of the lava flows are four aligned cinder cones. Students will be tasked with identifying the individual lava flows from each cinder cone and determining their relative ages based on field relations and aerial imagery. Field lectures will focus on the physical and chemical properties of mafic volcanism and will place the lava field in the broader context of Basin-and-Range extension. The final report will include map of the basaltic flows showing relative ages, volume calculations of the cinder cones and lava flows, and a geologic history of the region over the past 20,000 years.

At Summer Lake and Lake Abert, students will learn about lake chemistry and how environmental conditions are recorded in carbonate minerals.  Water samples will be collected and analyzed at camp for comparison to measurements made over the past 70 years. The group will also dig pits and make stratigraphic sections of ancient lake sediments to investigate how the region has changed on 103 to 104-year timescales. This will include an analysis of fossils, tephra beds, and detailed descriptions of the sub-units themselves (e.g., number of sub-units, thickness of each layer, size, shape, and texture of the different components of the deposit).

At Newberry Volcano, the group will quantify the volume and main textural characteristics of the tephra ejected during the explosive phase of the Big Obsidian Flow eruption. To do so, students will dig several 1-to-6-feet deep pits in the tephra fall deposit to obtain the thickness and a detailed description of this phase of the eruption. The students will work together with their collected data and data gathered from the literature and satellite/aerial images to make cross-sections, maps, and provide estimates on volume, extent, and viscosity of the various deposits and eruptive phases. This will allow them to develop a joint interpretation of sequence of events that took place during the last eruption of Newberry Volcano.

Abert Rim, Oregon, uplifted along a normal fault



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