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Toward a Four-Dimensional Petrogenetic Model of a Distributed Volcanic Field on the Southern Edge of the Colorado Plateau

Professional Paper 1890-N
By:  and 
https://doi.org/10.3133/pp1890N

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Abstract

A detailed characterization of the >3,000 square kilometer (km2) Springerville volcanic field, located on the southern tip of the Colorado Plateau in Arizona, United States, with its more than 501 volcanic units and widely distributed >420 cinder cones and lava flows, provides constraints toward an integrated petrogenetic model for the field. Large-volume effusive tholeiitic eruptions at 2–1.5 mega-annum (Ma) transitioned to more numerous, smaller volume alkali olivine basalt (AOB) events at 1.5–1.0 Ma, with increasing abundances of evolved alkalic rocks (EARs), and a final 1.0–0.3 Ma period dominated by smaller volume, more explosive alkalic eruptions.

Early large-scale melting in a relatively enriched lithospheric mantle (EM) source generated large-volume effusive tholeiitic magmas. Depths of tholeiite magma generation average about 90 kilometers (km) across the field, but depths for individual units decreased southward, consistent with lithospheric thinning toward the Colorado Plateau margin. Early and middle-stage transitional basalts, alkali olivine basalts (AOBs), and basanites originate from a progressively deeper (>100 km) region in a prevalent mantle (PREMA)-like asthenospheric source produced by increasingly smaller degrees of melting, as low as about 2 percent. The chemical signature of the basanites is consistent with small degrees of melting in a carbonated, asthenospheric source to depths of about 140 km. As heat waned, the last phase of volcanism was dominated by more explosive EARs derived at shallower lithospheric pressures but that have isotopic and trace element similarities to the deeper asthenospheric magmas. This suggests mixing between deeper basanitic and shallower tholeiitic magmas. With waning heat, eruptions became more localized along alignments, likely related to boundaries between blocks of Proterozoic crust with differing properties that affected magma ascent.

The petrogenetic patterns are consistent with a variety of processes. Basin and Range Province extension, melting, and heat-induced weakening progressively eroded the Colorado Plateau’s thicker lithosphere, giving rise to relatively high degrees of partial melting from shallower (<90 km) sources that produced the early large volumes of effusive tholeiitic magma. Possible lithosphere delamination and removal, and a resulting steep boundary step with the asthenosphere, may have given rise to mantle edge convection, resulting in the mixing of basanitic and tholeiitic magmas. With plate motion, shear-driven upwelling likely gave an eastward component to convection, affecting relative amounts of melting at the field’s western boundary and corresponding with volcanism moving eastward during times of peak vent production by eruption of alkalic lavas, giving rise to more explosive and lower volume eruptions.

Suggested Citation

Mnich, M.E., and Condit, C.D., 2026, Toward a four-dimensional petrogenetic model of a distributed volcanic field on the southern edge of the Colorado Plateau, chap. N of Poland, M.P., Ort, M.H., Stovall, W.K., Vaughan, R.G., Connor, C.B., and Rumpf, M.E., eds., Distributed volcanism—Characteristics, processes, and hazards: U.S. Geological Survey Professional Paper 1890, 25 p., https://doi.org/10.3133/pp1890N.

ISSN: 2330-7102 (online)

Study Area

Table of Contents

  • Abstract
  • Introduction
  • Methods
  • Results
  • Discussion
  • Conclusions
  • References Cited
Publication type Report
Publication Subtype USGS Numbered Series
Title Toward a four-dimensional petrogenetic model of a distributed volcanic field on the southern edge of the Colorado Plateau
Series title Professional Paper
Series number 1890
Chapter N
DOI 10.3133/pp1890N
Publication Date January 27, 2026
Year Published 2026
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Volcano Science Center
Description Report: v, 25 p.; 1 HTML Figure
Country United States
State Arizona, New Mexico
Online Only (Y/N) Y
Additional publication details