The plate tectonic setting of southeastern Arizona
— peter J. Coney

The regional tectonic evolution of southwestern North America has been dominated by a succession of variable and rapidly changing plate tectonic settings since Paleozoic time. Although seemingly far removed from a plate margin, south-eastern Arizona lies well within a broad belt which has experienced complex continental plate tectonic activity over the past 200 m.y.

 

This prolonged period of complex continental tectonics can be divided into six phases: a Paleozoic period of extended cratonic stability; a Late Triassic to Late Jurassic period of magmatic arc activity; a Cretaceous period during which the region was in an arc-rear setting; an intense period of compressive deformation and magmatic arc activity during Late Cretaceous to early Tertiary (Laramide) time; a middle Tertiary period of calderas and evolution of metamorphic core com-plexes; and finally, Late Tertiary Basin and Range rifting. Perhaps the most unique aspect of the tectonic evolution of this region was the complex interplay of plate tectonic events in two oceans—the Pacific Ocean to the southwest and the Gulf of Mexico to the southeast—and a very complex magmatic arc evolution during Mesozoic-Cenozoic time.