Paleogene calderas of central and eastern Oregon: Eruptive sources of widespread tuffs in the John Day and Clarno Formations
McClaughry JD, Ferns ML, Streck MJ, Patridge KA, Gordon CL. 2009. Paleogene calderas of central and eastern Oregon: Eruptive sources of widespread tuffs in the John Day and Clarno Formations. Pages 407-434. In O'Connor J, Dorsey R, Madin I (ed). Volcanoes to Vineyards: Geologic Field Trips through the Dynamic Landscape of the Pacific Northwest. Boulder, Colorado. Field Guides. Field Guide 15
The John Day Formation of central and eastern Oregon, contains a widespread assemblage of both ash-flow and airfall tuffs, yet only a few corresponding caldera sources have been identified in the region. Investigators have long speculated on the sources of tuffs in the John Day Formation and have suggested that these pyroclas-tic rocks were vented from now buried eruptive centers in or marginal to a nascent Cascade Range. Recent detailed geologic mapping in the John Day and Clarno Formations, however, indicates the presence of at least three large-scale rhyolite caldera complexes centered along the northeast-trending axis of the Blue Mountains. This field guide describes a three-day geologic transect, from the scenic high desert of central Oregon eastward across the axis of the Blue Mountains, that will examine the physical volcanology and geologic setting of the 41.50–39.35 Ma Wildcat Mountain caldera exposed along the crest of the Ochoco Mountains, the 29.56 Ma Crooked River caldera at Prineville, and the 29.8 to 28.1 Ma Tower Mountain caldera near Ukiah.
- Type
- Book Chapter
- Authors
- McClaughry, Jason; Ferns, Mark; Streck, Martin; Patridge, Karyn; Gordon, Caroline
- Units
- JODA