In southeastern California and west-central Arizona, Mesozoic polyphase deformation fabrics and basement-involved structures in the MariaTectonic Belt trend west-northwest at a high angle to the Mesozoic magmatic arc and thin-skinned Sevier fold and thrust belt. The Maria belt extends from the Granite Wash and Harquahala Mountains, Arizona, to the Old Woman Mountains and Piute Range, California. All of the ranges in the belt share a common history of northeast-and/or southwestdirected shear superposed on earlier fabrics. Crustal shortening began in the Jurassic and culminated in Late Cretaceous greenschist to amphibolite facies metamorphism and crustal anatexis. Variability of deformation style and poor timing constraints have hampered integration of Maria belt deformation with the rest of the Cordilleran orogen. Our mapping and geochronology in the Dome Rock Mountains provides a framework for establishing the tectonic evolution of the Maria belt within the context of previous models for the Mesozoic Cordilleran orogen. A km-scale F 1 recumbent syncline and associated minor structures in the northern Dome Rock Mountains predate intrusion of ca. 161 Ma leucocratic granite, postdate intrusion of ca. 164 Ma granodiorite, and are interpreted to have accommodated shortening along the northern margin of the Middle Jurassic magmatic arc. F 2 folds and shear zones deform ca. 161 Ma leucocratic granite and are attributed to top-tothe-southwest, reverse-sense motion in the footwall of the Tyson thrust. Southwestdirected deformation in the northern Dome Rock Mountains ceased prior to the intrusion of a Late Cretaceous granite that crosscuts the Tyson thrust. Northeastdirected extensional strain (D 3 ) reactivated previously southwest-vergent shear zones and resulted in translation of Triassic metasedimentary rocks down to the northeast from an original position in the core of an F 1 /F 2 fold nappe. Extensional structures are recognized in Late Cretaceous granite that developed prior to middle Tertiary Cordilleran metamorphic core complexes as indicated by early Tertiary biotite 40 Ar/ 39 Ar and K/Ar cooling ages from mylonitic rocks. Boettcher, S.S., Mosher, S., and Tosdal, R.M., 2002, Structural and tectonic evolution of Mesozoic basement-involved fold nappes and thrust faults in the Dome Rock Mountains, Arizona, in Barth, A., ed., Contributions to Crustal Evolution of the Southwestern

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