9-5 An Update on the Geologic Mapping of Five USGS Quadrangles Northwest of Mt. McLoughlin, Oregon

Session: Advances in Geologic Mapping, Databases, and Dissemination: Student Posters

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Since 2013, a program in volcanic mapping based out of the University of Minnesota – Morris has been progressively expanded in five USGS 7.5’ quadrangles west and north of Mt. McLoughlin, Oregon.  This work, which has to date incorporated the efforts of no fewer than thirteen undergraduate students, has focused on the quadrangles Willow Lake, Rustler Peak, Big Butte Springs, Prospect South, and Imnaha Creek, forming a contiguous area south of Crater Lake National Park within the mafic-dominated southern Oregon Cascades.  The lavas exposed are dominantly calc-alkaline basalt and basaltic-andesite, but with notable outcrops of tholeiitic basalt, andesitic-to-dacitic pumice and tuff, and a singular hornblende-andesite summit exposure atop Rustler Peak.  In a continuation built upon prior work by our research group, supplemented by earlier sampling by Franklin & Marshall College Prof. Stanley Mertzman, the samples from these map areas, numbering over 250 collectively, have been compared in terms of their bulk hand-sample and geochemical characteristics.  These comparisons have enabled the delineation into discrete units, with geological maps and unit information currently being prepared for formal publication using the updated GeMS package by the USGS.

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