The Boot Heel volcanic field is located in the Bootheel region of southwest New Mexico, adjacent areas of southeastern Arizona, and northwest Mexico. The field covers an area of more than 24,000 km2.[2] The field includes nine volcaniccalderas ranging in age from 26.9 to 35.3 Ma. Extrusive products include rhyolitic ignimbrites along with basalt, andesite, and rhyolitelava flows. The major ash flow tuff sheets produced, range in volume from 35 to 650 km3.[2]
Activity throughout most of the Boot Heel volcanic field paused between 33 and 28 million years ago. The earlier pulse of activity involved less evolved magmas, while the later pulse was relatively depleted in volatiles.[3] The pause in activity has been interpreted as a period of tectonic reorganization along the west coast of North America, including the birth of the San Andreas Fault, that temporarily shifted volcanism to the east.[4]
The Geronimo volcanic field (also known as the San Bernardino volcanic field) is a monogeneticvolcanic field and a sub-section of the Boot Heel volcanic field in southeastern Arizona, US.[1]
Calderas
The calderas of the Boot Heel field and their associated ignimbrites include:[2][7]
^ abdu Bray, Edward A.; Pallister, John S.; Snee, Lawrence W. (2004). "Geochemistry and Geochronology of Middle Tertiary Volcanic Rocks of the Central Chiricahua Mountains, Southeast Arizona". United States Geological Survey Professional Paper. 1684. doi:10.3133/pp1684. hdl:2027/osu.32435071403786.