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Peralkaline ash flow tuffs and calderas of the McDermitt volcanic field, southeast Oregon and north central Nevada.

January 1, 1984

This volcanic field covers an area of 20 000 km2 and consists of seven large-volume ash-flow sheets that vented 16.1-15 m.y. ago. The volcanic field is characterized by peralkaline, high-silica rhyolite, and all but one of the sheets are comendites. Each ash-flow sheet resulted in the formation of a large collapse caldera. Thickening of the ash-flow sheets, monoclinal warping outside the caldera ring-fault and tilting-in towards the caldera of blocks bounded by curvilinear faults all indicate regional subsidence prior to caldera collapse. The McDermitt caldera complex is highly mineralized; it contains ore deposits of Hg, Sb, Cs, Li and U. The peralkaline tuffs have high contents of these elements and were the source rocks from which metals were leached by hydrothermal systems developed during the last stage of caldera-related volcanism. (Following abstract) -W.H.B.

Publication Year 1984
Title Peralkaline ash flow tuffs and calderas of the McDermitt volcanic field, southeast Oregon and north central Nevada.
Authors J. J. Rytuba, E. H. McKee
Publication Type Article
Publication Subtype Journal Article
Series Title Journal of Geophysical Research
Index ID 70013970
Record Source USGS Publications Warehouse