ERTH 406 Field Studies in Fire and Ice (CRN 42747) 4 credits Instructors: Meredith Townsend and Leif Karlstrom. Graded for Majors; P/NP optional for all other students. $800 course fee and usual tuition and UO fees.
This course begins in Santiam Pass, located in the heart of Oregon Cascades Volcanic Arc. The Cascade Volcanoes been active for over 30 million years, producing a variety of volcanic deposits including cinder cones, pyroclastic flows, lava flows, and large composite volcanoes. Over this time, the local climate and hydrology have changed drastically, including glacial-interglacial cycles that have shaped the landscape through erosion and transport of glacial sediments. We will see a diversity of volcanic, glacial, and glacio-volcanic features to learn about the interactions between ice, water and volcanism in a subduction zone setting. In addition, we will visit Newberry Volcano located in the back-arc region, where we will explore evidence for a large and active subsurface magmatic system through surface topography, recent eruptive deposits (such as the Big Obsidian Flow that erupted 1300 years ago), and active hydrothermal features.
The second portion of this course will be in the Wallowa Mountains, where students will map and characterize feeder dikes of the Columbia River Flood basalts, an enormous outpouring of magma that occurred roughly 16 million years ago. The dikes exposed in this region are associated with some of the largest known basaltic eruptions on Earth, and are uniquely exposed due to the uplift of the Wallowa Mountains. Students will map and characterize dike structures and look at melting reactions in granitoid host rocks caused by heating associated with flowing magma in the dikes. Field measurements along with simple physical models will be integrated to understand magma transport in the shallow crust during flood basalt emplacement. Students will also visit and examine Columbia River basalt lava flows exposed in the Grande Ronde River canyon, where fluvial incision has exposed dike and lava flow interactions on a grand scale.