Simplified stratigraphic section of the Peach Spring Tuff and associated volcanic strata in the Kingman area; Figure 10 of Ferguson 2016 AGS field guide cited below.
Background: The 18.8 Ma Peach Spring Tuff’s presence over nearly 20,000 km2 of the southern Basin and Range province makes it the principal strain and time marker in one of the world’s most intensively studied extensional belts (Glazner et al.,1986). After decades of intensive study however, the search for its source caldera yielded nothing. Then, during a routine, 2006 highway survey suggested and funded through the vision of ADOT geological engineer Nicolas M. Priznar. the elusive caldera was identified by Arizona Geological Survey geologists along the eastern edge of the Colorado River Extensional Corridor (CREX) near Oatman, Arizona. Online resource: Ferguson, C.A., 2016, The Peach Spring Tuff, its source caldera, and implications for structural geology of the Colorado River Extensional Corridor. Arizona Geological Society 2016 Fall Field Trip, 29 p. http://repository.azgs.az.gov/uri_gin/azgs/dlio/1878