New in Geosphere—McDermitt Caldera Research

Geology and evolution of the McDermitt caldera, northern Nevada and southeastern Oregon, western USA

by Christopher D. Henry, Stephen B. Castor, William A. Starkel, Ben S. Ellis, John A. Wolff, Joseph A. Laravie, William C. McIntosh, and Matthew T. Heizler

Geosphere; v. 13, no. 4
Published: July 2017

The McDermitt caldera (western USA) is commonly considered the point of origin of the Yellowstone hotspot, yet until now no geologic map existed of the caldera and its geology and development were incompletely documented. We developed a comprehensive geologic framework through detailed and reconnaissance geologic mapping, extensive petrographic and chemical analysis, and high-precision 40Ar/39Ar dating. The caldera formed during eruption of the 16.39 ± 0.02 Ma (n = 3) McDermitt Tuff (named here), which is strongly zoned from peralkaline, aphyric, high-Si rhyolite (comendite) to metaluminous, abundantly anorthoclase-phyric, trachydacite, or Fe-rich andesite (icelandite).

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