Synextensional dike emplacement across the footwall of a continental core complex, Chemehuevi Mountains, southeastern California

LaForge, J.; John, Barbara E.; Grimes, C. B.

doi:10.1130/ges01402.1

Cited by 4 publications

(3 citation statements)

References 47 publications

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“…Interestingly, extension directions recorded by early Miocene dikes in the lower Colorado River extensional corridor typically do not closely match the extension direction recorded by detachment slip or mylonitic lineations. For example, the mean extension direction associated with early Miocene dikes in the southwest Whipple Mountains (southeastern California, USA) is ~30° clockwise of the dominant NE-SW core complex extension direction (Gans and Gentry, 2016) high angle to the NE-SW extension direction from mylonitic lineations and detachment fault slickenlines (LaForge et al, 2017). Considering all of these factors, we consider 054° ± 2° to be the best estimate of the Miocene core complex extension direction in the Harquahala Mountains (Fig.…”

Section: Total Dextral Slip Across the Harquahala And Harcuvar Mountainsmentioning

confidence: 99%

Distributed Neogene faulting across the western to central Arizona metamorphic core complex belt: Synextensional constriction and superposition of the Pacific–North America plate boundary on the southern Basin and Range

et al. 2019

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We present fault data from a belt of Miocene metamorphic core complexes in western and central Arizona (USA) to determine patterns of brittle strain during and after large-magnitude extension, and to evaluate the magnitude of postextensional dextral shear across the region. In the White Tank Mountains, coeval WNW-to NW-striking dextral, normal, and oblique dextral-normal faults accommodated constrictional strain with extension subparallel to the direction of ductile stretching during core complex development. Northwest-striking oblique dextral-normal faults locally accommodated similar strain in the Harquahala Mountains, whereas in the South Mountains, constriction was primarily partitioned on NE-dipping normal faults and conjugate NW-and north-striking strike-slip faults. We interpret brittle constrictional strain to have developed during the late stages of large-magnitude extension associated with core complex development and folding of detachment fault corrugations. The oblique orientation of the Arizona core complex belt with respect to the extension direction likely resulted in a minor component of dextral transtension, accounting for much of the constrictional strain. In addition, far-field stresses associated with the transtensional Pacific-North America plate boundary may have contributed to constriction, which characterizes most Neogene detachment fault systems in the southwest Cordillera. Following cessation of detachment fault slip across the Arizona core complex belt (ca. 14-12 Ma), distributed NW-striking dextral and oblique dextral-NE-side-up (reverse) faults modified the topographic envelope of corrugations to an orientation clockwise of the core complex extension direction. Based on our analysis of this misalignment, we interpret the postdetachment fault dextral shear strain to increase northwestward from 0.03 across the South Mountains (0.5-0.6 km total slip across 18 km) to >0.03-0.07 across the Harquahala and Harcuvar Mountains (1.2-2.5 km of total slip across ~35 km) and ~0.2 across the Buckskin-Rawhide Mountains (7-8 km across 36 km). This along-strike variation in dextral shear is consistent with the regional pattern of distributed strain associated with the Pacific-North America plate boundary, as cumulative dextral offset in the lower Colorado River region increases toward the eastern Mojave Desert region to the northwest.

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Section: Total Dextral Slip Across the Harquahala And Harcuvar Mountainsmentioning

confidence: 99%

Distributed Neogene faulting across the western to central Arizona metamorphic core complex belt: Synextensional constriction and superposition of the Pacific–North America plate boundary on the southern Basin and Range

et al. 2019

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“…The orange line is a moving average (period = 50) of magmatic dates compiled from EarthChem. The start and end of rapid cooling for metamorphic core complexes is reported inFoster and Spencer (1992),John and Foster (1993),Fitzgerald et al (1993),Miranda-Gasca et al (1998),Pease et al (1999),Granillo and Calmus (2003),Haines and van der Pluijm (2008),Carter et al (2004),Wong and Gans (2008),Wong et al (2010),Singleton et al (2014Singleton et al ( , 2019,Prior et al (2016), LaForge et al (2017,Jacobson et al (2019),Gottardi et al (2020), andJepson et al (2022). (b) Schematic plate reconstructions showing the subduction of the Pacific-Farallon spreading ridge, the initiation of the MTJ and RTJ, the development of the dextral-transform Pacific-North American plate boundary, and the San Andreas Fault system (SAFS).…”

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confidence: 89%

Oligocene‐Miocene Exhumation of the Pinaleño Metamorphic Core Complex, Southeastern Arizona: Support for Magmatism and Plate Margin Reorganization as Controls on Regional Exhumation Trends

Chapman,

Scoggin,

Jepson

et al. 2024

Tectonics

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The Pinaleño Mountains of southeastern Arizona is the eastern‐most metamorphic core complex in the southern U.S. and northern Mexican Cordillera. This study investigates the thermal history and exhumation record of the Pinaleño core complex using mica 40Ar/39Ar, apatite and zircon (U‐Th)/He, and apatite fission‐track thermochronometers. The Pinaleño Mountains experienced two periods of rapid cooling during the Cenozoic. The first period, from ca. 27 to 21 Ma, records tectonic exhumation related to the development of the core complex and extensional shear zone. This period was followed by a relatively quiescent interval from 21 to 13.5 Ma that records little to no exhumation. The second period of rapid cooling, from 13.5 to 11 Ma, records tectonic exhumation related to high‐angle normal faulting, characteristic of the Basin and Range province. The exhumation timing of the Pinaleño core complex matches previously recognized spatiotemporal trends in the southern Basin and Range province and indicates that core complex exhumation in this region started in southeastern Arizona (ca. 32–33°N) and migrated both northward and southward. These trends correlate well with the latitude and timing of subduction of the Pacific‐Farallon spreading ridge and the migration of the Mendocino (northward) and Rivera (southward) triple junctions. Spatiotemporal core complex exhumation trends also correlate well with regional magmatism associated with the mid‐Cenozoic flare‐up, including syn‐extensional intrusive rocks found in the footwalls of core complexes.

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“…The wide variety of papers in this themed issue aptly honors the diversity and significance of Art's own contributions. Taken together, the papers represent the broad scope of active margin evolution through geologic time from the Neoarchean (Frost et al, 2018;Swapp et al, 2018) to the Miocene (LaForge et al, 2017). Geographically, most papers focus on diverse aspects of the long time-scale tectonic evolution of the Cordilleran margin of western North America.…”

Section: ■ Volume Contributionsmentioning

confidence: 99%

Introduction: Active Margins in Transition—Magmatism and Tectonics through Time: An Issue in Honor of Arthur W. Snoke

McGrew

Schwartz

2021

Geosphere

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The evolution of active margins through time is the record of plate tectonics as inscribed on the continents. This themed issue honors the eclectic contributions of Arthur W. Snoke (Fig. 1) to the study of active margins with a series of papers that amply demonstrate the broad scope of active margin tectonics and the diverse methods that tectonic geologists employ to decipher their histories. Taken together, this set of papers illustrates the diversity of boundary conditions that guide the development of active margins and the key parameters that regulate their evolution in time and space.

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Synextensional dike emplacement across the footwall of a continental core complex, Chemehuevi Mountains, southeastern California

Cited by 4 publications

References 47 publications

Distributed Neogene faulting across the western to central Arizona metamorphic core complex belt: Synextensional constriction and superposition of the Pacific–North America plate boundary on the southern Basin and Range

Distributed Neogene faulting across the western to central Arizona metamorphic core complex belt: Synextensional constriction and superposition of the Pacific–North America plate boundary on the southern Basin and Range

Oligocene‐Miocene Exhumation of the Pinaleño Metamorphic Core Complex, Southeastern Arizona: Support for Magmatism and Plate Margin Reorganization as Controls on Regional Exhumation Trends

Introduction: Active Margins in Transition—Magmatism and Tectonics through Time: An Issue in Honor of Arthur W. Snoke

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