Abstract

Strato-tectonic analysis of Late Cretaceous - Cenozoic stratigraphy, structure, and resources of Arizona and adjacent regions reveals the presence of three major diachronous orogenic events: 1) Laramide orogeny of late Cretaceous to late Eocene; 2) Galiuro orogeny (new) of late Eocene to mid-Miocene, which was formerly called the mid-Tertiary orogeny; and 3) San Andreas orogeny (new) of late Miocene to present, which includes Basin-Range nomenclature.

Laramide orogeny in the Basin and Range Province consists of five major, eastward-younging, sequential assemblages that include, from oldest to youngest: 1) metaluminous, quartz alkalic, hydrous magmatism; Cu-Au porphyry deposits; and E-W to WNW-trending, wedge uplifts and folds (Hillsboro assemblage); 2) metaluminous, alkali-calcic, hydrous magmatism; Pb-Zn-Ag vein and replacement deposits; and NE-directed folds and thrusts (Tombstone assemblage); 3) metaluminous, calc-alkalic, hydrous magmatism; large zoned porphyry Cu-Mo systems; and E-W to NE-striking dikes and distributed left shear on WNW-striking faults (Morenci assemblage); 4) peraluminous, subalkaline, hydrous plutonism; regional-scale, SW-directed thrust faults and related mylonitic deformation (Wilderness assemblage); and 5) greenschist-grade, mostly sodic, metagraywacke beneath crustal-scale, SW-directed, thrusts (Orocopia assemblage).

Galiuro orogeny consists of three major, westward-younging, sequential assemblages that include, from oldest to youngest: 1) low-energy sedimentation in reverse(?)-faulted basins (Mineta assemblage); 2) extensive, metaluminous, calc-alkalic and alkali-calcic, hydrous ignimbritic magmatism; Au-Ag-W and Pb-Zn-Ag veins and replacements; local, coarse clastic sedimentation with megabreccia units; and crustal-scale, NW-SE-trending, broad folds, and. NW-striking reverse(?) faults (Galiuro assemblage); and 3) metaluminous, alkalic, hydrous magmatism; Au-Ag veins and minor Cu replacements; coarse clastic sedimentation; major low-angle normal (detachment) faults, minor reverse faults, and continued crustal-scale warping (Whipple assemblage).

San Andreas orogeny consists of two orogenic assemblages: 1) NE-SW to E-W trending folds (Transverse assemblage); and 2) metaluminous, alkaline, anhydrous, iron-rich, magmatism; N-S trending horsts and grabens; internally drained, lacustrine basins with fringing coarse clastics; and industrial mineral deposits (Basin and Range assemblage).