The North American Cordilleran Anatectic Belt

Chapman, James B.; Runyon, Simone E.; Shields, Jessie E.; Lawler, Brandi L.; Pridmore, Cody J.; Scoggin, Shane; Swaim, Nathan T.; Trzinski, Adam; Wiley, Hannah N.; Barth, Andrew P.; Haxel, Gordon B.

doi:10.1016/j.earscirev.2021.103576

Cited by 25 publications

(28 citation statements)

References 305 publications

(387 reference statements)

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“…3). These data are also consistent with eastward migration of magmatism away from the coastal arcs after 75 Ma which has been interpreted to re ect shallowing of the subduction angle over time 4,43,44 . We illustrate these features in our model (Fig.…”

Section: Zircon Geochronologysupporting

confidence: 80%

Magmatic Surge Requires Two-Stage Model for the Laramide Orogeny

Schwartz

Lackey

Miranda

et al. 2023

Preprint

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The beginning of the Laramide orogeny is a pivotal time in the geological development of the western United States, but the driving mechanism responsible for mountain building, basin formation and ore mineralization is controversial. Most prominent models suggest this event was caused by the collision of an oceanic plateau with western North America at ca. 88 Ma which caused the angle of subduction beneath the continent to shallow. This subhorizontal (flat) subduction is thought to have led to shut-down of the arc, crustal cooling, and the formation of deep, basement-involved thrust faults that penetrated far into the continental interior. In contrast to these predictions, we show that the arc experienced a magmatic surge, the lower crust was hot (835-750°C) and partially molten from 90 to 70 Ma, and cooling occurred after 75 Ma. These data contradict plateau underthrusting as the driving mechanism at 90-80 Ma; therefore, the Laramide orogeny cannot have been initiated by flat-slab subduction. We propose that the Laramide orogeny is best explained as a two-stage orogeny consisting of a syn-magmatic phase at 90-75 Ma, and a widespread mountain building phase at 75-50 Ma. Only that latter phase is linked to flat-slab subduction.

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Section: Zircon Geochronologysupporting

confidence: 80%

Magmatic Surge Requires Two-Stage Model for the Laramide Orogeny

Schwartz

Lackey

Miranda

et al. 2023

Preprint

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“…B. Chapman et al, 2021). This is consistent with a cycle of crustal thickening producing localized crustal melting from heating and dehydration-derived fluids, which triggered crustal collapse of overthickened crust (Figure 14).…”

Section: Regional Tectonic Implicationssupporting

confidence: 76%

“…The leucogranite is typically peraluminous with two micas ± garnet, suggesting it was derived from significant crustal melting (Farmer & DePaolo, 1983; Haxel et al., 1984; Lee et al., 1981; Miller & Barton, 1990; Miller & Bradfish, 1980; Patino‐Douce et al., 1990; Wright & Wooden, 1991, see review by J. B. Chapman et al., 2021). This is consistent with a cycle of crustal thickening producing localized crustal melting from heating and dehydration‐derived fluids, which triggered crustal collapse of overthickened crust (Figure 14).…”

Section: Discussionmentioning

confidence: 99%

Late Cretaceous‐Early Paleogene Extensional Ancestry of the Harcuvar and Buckskin‐Rawhide Metamorphic Core Complexes, Western Arizona

et al. 2023

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Metamorphic core complexes in the western North American Cordillera are commonly interpreted as the result of a single phase of large‐magnitude extension during the middle to late Cenozoic. We present evidence that mylonitic shear zones in the Harcuvar and Buckskin‐Rawhide core complexes in west‐central Arizona also accommodated an earlier phase of extension during the Late Cretaceous to early Paleocene. Microstructural data indicate substantial top‐NE mylonitization occurred at amphibolite‐facies, and 40Ar/39Ar thermochronology documents post‐tectonic footwall cooling to <500°C by the Paleocene to mid‐Eocene. Amphibolite‐facies mylonites are spatially associated with voluminous and variably deformed footwall leucogranites that were emplaced from ca. 74–64 Ma, and a late kinematic ca. 63 Ma dike indicates this phase of mylonitization had waned by the early Paleocene. Reconstruction of the footwall architecture indicates that this latest Cretaceous—early Paleocene deformation occurred within a NE‐dipping extensional shear zone. The leucogranites were likely the result of crustal melting due to orogenic thickening, consistent with a model whereby crustal heating triggered gravitational collapse of overthickened crust. Other tectonic processes, such as the Laramide underplating of Orocopia Schist or mantle delamination, may have also contributed to this episode of orogenic extension. Miocene large‐magnitude extension was superimposed on this older shear zone and had similar kinematics, suggesting that the location and geometry of Miocene extension was strongly influenced by tectonic inheritance. We speculate that other Cordilleran core complexes also experienced a more complex and polyphase extensional history than previously recognized, but in many cases the evidence may be obscured by later Miocene overprinting.

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“…The spatial and temporal association of voluminous Late Cretaceous Tank Pass leucogranite with coeval extensional fabrics strongly suggests that the leucogranite played an important role in this tectonic event. The leucogranite is typically peraluminous with two micas ± garnet, suggesting it was derived from significant crustal melting (Miller and Bradfish, 1980;Lee et al, 1981;Farmer and DePaolo, 1983;Haxel et al, 1984;Miller and Barton, 1990;Patiño-Douce et al, 1990;Wright and Wooden, 1991, see review by Chapman et al, 2021). This is consistent with a cycle of crustal thickening producing localized crustal melting from heating and dehydration-derived fluids, which triggered crustal collapse of overthickened crust (Figure 14).…”

Section: Regional Tectonic Implicationsmentioning

confidence: 73%

Late Cretaceous-early Paleogene extensional ancestry of the Harcuvar and Buckskin-Rawhide metamorphic core complexes, western Arizona

Wong

Singleton

Seymour

et al. 2022

Preprint

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Metamorphic core complexes in the western North American Cordillera are commonly interpreted as the result of a single phase of large-magnitude extension during the middle to late Cenozoic. We present evidence that mylonitic shear zones inthe Harcuvar and Buckskin-Rawhide core complexes in west-central Arizona also accommodated an earlier phase of extension during the Late Cretaceous to early Paleocene. Microstructural data indicate substantial top-NE mylonitization occurred at amphibolitefacies, and 40 Ar/ 39 Ar thermochronology documents post-tectonic footwall cooling to <500°C by the Paleocene to mid-Eocene. Amphibolite-facies mylonites are spatially associated with voluminous and variably deformed footwall leucogranites that were emplaced from ca. 74-64 Ma, and a late kinematic ca. 63 Ma dike indicates this phase of mylonitization had waned by the early Paleogene. Reconstruction of the footwall architecture indicates that this latest Cretaceous -early Paleocene deformation occurred within a NE-dipping extensional shear zone. The leucogranites were likely the result of crustal melting due to orogenic thickening, implying a model whereby crustal heating triggered gravitational collapse of overthickened crust. Other tectonic processes, such as the Laramide underplating of Orocopia Schist or mantle delamination, may have also contributed to this episode of orogenic extension. Miocene large-magnitude extension was superimposed on this older shear zone and had similar kinematics, suggesting that the location and geometry of Miocene extension was strongly influenced by tectonic inheritance.We speculate that other Cordilleran core complexes also experienced a more complex and polyphase extensional history than previously recognized, but in many cases the evidence may be obscured by later Miocene overprinting.

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The North American Cordilleran Anatectic Belt

Cited by 25 publications

References 305 publications

Magmatic Surge Requires Two-Stage Model for the Laramide Orogeny

Magmatic Surge Requires Two-Stage Model for the Laramide Orogeny

Late Cretaceous‐Early Paleogene Extensional Ancestry of the Harcuvar and Buckskin‐Rawhide Metamorphic Core Complexes, Western Arizona

Late Cretaceous-early Paleogene extensional ancestry of the Harcuvar and Buckskin-Rawhide metamorphic core complexes, western Arizona

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