At Jerome, Arizona, mafic volcanics, felsic volcanics, and tuffaceous sedimentary rocks comparable to many Archean sequences in the Canadian Shield are folded into a northeast trending dome. The northern half of the dome is flexed sharply northwest and its eastern limb is thrust west and upward more than 3,000 feet. Proterozoic quartz porphyry dikes and bodies of irregular shape and gabbro sheets were emplaced in volcanic rocks and postdate part of the folding. Sulfides occur in the quartz porphyry and volcanic rocks and in the U.V.X. mine, along a thrust fault, which ends the eastern extension of gabbro and quartz porphyry sheets on the hanging-wall and the footwall sides, respectively, of the United Verde massive sulfide deposit. The relative ages and associations of sulfides, gabbro, and quartz porphyry are interpreted to imply derivation from a common magmatic source.