Structural and tectonic evolution of Mesozoic basement-involved fold nappes and thrust faults in the Dome Rock Mountains, Arizona

Abstract

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

Orocopia Schist in the northern Plomosa Mountains, west-central Arizona: A Laramide subduction complex exhumed in a Miocene metamorphic core complex

“…Latest Cretaceous to early Paleogene NE-SW extension is also inferred in the nearby Dome Rock Mountains, Harcuvar Mountains, and Buckskin-Rawhide Mountains (Fig. 1) (Boettcher et al, 2002;Wong et al, 2013;Singleton and Wong, 2016). These ranges apparently lack Orocopia Schist, but evidence for Laramide-age extension in this region supports the interpretation that Paleogene exhumation was widespread throughout southern California and western Arizona.…”

Geodynamics of Cenozoic extension along a transect across the Colorado River extensional corridor, southwestern USA

“…3). The style of deformation in these rocks is generally similar to that of the Maria fold-and-thrust belt elsewhere (e.g., Hamilton, 1982;Boettcher et al, 2002).…”

“…1.7 Ga underlies the Paleozoic strata in southwestern North America (Richard et al, 2000). Lower Mesozoic strata were locally affected by deformation before eruption of widespread Jurassic felsic volcanic rocks, emplacement of granitoids, and local tectonic shortening Tosdal et al, 1989;Boettcher et al, 2002;Tosdal and Wooden, 2015). Jurassic magmatism across southern Arizona and southeastern California was followed by latest Jurassic rifting and associated deposition of the lower part of the McCoy Mountains Formation (Tosdal and Stone, 1994;Spencer et al, 2011).…”

“…2). This entire zone is readily interpreted as a north-dipping thrust zone that was part of the Maria fold and thrust belt (Reynolds et al, 1986; Spencer and Reynolds, 1990b) with possible Jurassic antecedents (Boettcher et al, 2002). The deformation zone is much more complex than a simple thrust fault and its sheared footwall, however, as indicated by the complex, multiple deformations in the Quinn Pass shear zone (Stoneman, 1985a(Stoneman, , 1985bSteinke, 1996Steinke, , 1997, the southern Plomosa Mountains (Richard et al, 1993), and the Boyer Gap area (Boettcher et al, 2002).…”

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“…Deformation in the Sevier fold-and-thrust belt also seems to have waned in this time, especially in southern Nevada and nearby Utah, where thrusting appears to have halted by 87-81 Ma, prior to the start of Laramide tectonism (Barth et al, 2004;Burchfi el and Davis, 1977), and in the Maria fold and thrust belt of southeastern California and western Arizona, which shortened until 85 Ma (Barth et al, 2004;Boettcher et al, 2002;Karlstrom et al, 1993) and possibly until 70 Ma on the Mule Mountains thrust (Tosdal, 1990;Tosdal and Stone, 1994). Farther north, shortening continued on frontal thrusts through most of the Laramide (DeCelles, 2004;DeCelles and Coogan, 2006), ceasing and then reversing into extensional faulting toward the close of the Laramide (Constenius, 1996).…”