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July Lecture: A Tail Between Two Cities: the Yellowstone Plume (Head and Tail) Between John Day and Burns, Oregon

  • Cramer Hall, Portland State University 1721 Southwest Broadway Portland, OR, 97201 United States (map)

Emily Cahoon's talk will focus on volcanic deposits around the John Day Valley and further south to Burns, Oregon. This includes the Clarno Formation, John Day Formation, and lots of mid-Miocene lavas and tuffs. Also, there are unstudied Oligocene to mid-Miocene basaltic lavas and dikes exposed south and east of known Picture Gorge Basalt (PGB) localities. These help to reevaluate PGB distribution and to better understand evolution, mantle components, and possible petrogenetic connections among PGB, Steens Basalt, and the Strawberry Volcanics. Broadly, we will explore the proposed connections between the John Day Formation, the Columbia River Basalts, and the Yellowstone plume.

Emily Cahoon is a 3rd year PhD Candidate at Portland State University. She received her BS from the University of Delaware in geological sciences and continued studying geology at Washington State University where she earned her MS investigating volcaniclastic deposits of the Clarno Formation in eastern Oregon. Her current research interests broadly cover the petrogenesis and geochemistry of basaltic magmas. Specifically, her dissertation examines the Picture Gorge Basalt (CRBG) via trace element and isotopic signatures to assist in geochemical modeling and interpretation of magmatic components during Oligocene and Miocene time in central and eastern Oregon.