Paleosubduction geometries Inferred from Cretaceous and Tertiary magmatic patterns in southwestern North America

Keith, Stanley B.

doi:10.1130/0091-7613(1978)6<516:pgifca>2.0.co;2

Cited by 108 publications

(53 citation statements)

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“…3K). In either case, the result was the rapid decompression melting of the inflow ing asthenosphere, with resulting outpouring of silicic magma over much of the southwestern United States-the "ignimbrite flare-up" (Coney and Reynolds, 1977;Cross and Pilger, 1978;Keith, 1978;Lipman, 1992). Rapid extension of parts of the Cordilleran region began concurrently with this thermal event, although space-time relations of magmatism and taphrogeny are complex (Axen et al, 1993).…”

Section: Oligocene Ignimbrite Flare-upmentioning

confidence: 93%

“…3J) (Coney, 1976;Dickinson and Snyder, 1978;Bird, 1984Bird, , 1988Engebretson et al, 1985;Cross, 1986;Spencer, 1996). The magmatic arc migrated eastward rapidly and then dissipated as the Farallon plate no longer interacted with asthenosphere underlying the Cordillera (Coney and Reynolds, 1977;Keith, 1978). Con tinental lithosphere likely was stripped from beneath the western part of the continental margin and accumulated in the modern Rocky Mountain and Great Plains areas (Bird, 1984(Bird, , 1988.…”

Section: Latest Cretaceous-eocene Laramide Orogenymentioning

confidence: 95%

“…Sinking of oceanic lithospheric slabs generates melts at depths of ~150 km (e.g., Coney and Reynolds, 1977;Keith, 1978Keith, , 1982Lipman, 1992). Rising magmas form mag matic arcs at the surface, as part of either oceanic or continental crust.…”

Section: Intraoceanic Magmatic Arcmentioning

confidence: 99%

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Phanerozoic Tectonic Evolution of Central California and Environs

Ingersoll

1997

International Geology Review

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The use of actualistic analog models for paleotectonic reconstruction produces significant advances in our understanding of evolutionary continental tectonics. The sequential application of such models is possible in a cross section from the central California coast to Utah. This transect represents one of the best-understood Phanerozoic continental margins on Earth. Excellent exposure, detailed local studies, and regional syntheses all contribute to the choice of appropriate plate-tectonic models for successive intervals from the latest Neoproterozoic to the Quaternary. These models include craton, terrestrial rift, nascent ocean, intraplate continental margin, intraoceanic magmatic arc (both extensional and neutral), continental-margin magmatic arc (both neutral and contractional), transform continental margin, remnant ocean, suture, and successor basin. These models are useful for understanding the following stages of development of the Cordilleran margin of central California and its environs-latest Proterozoic rifting, early Paleozoic intraplate margin, Devonian-Mississippian Antler orogeny (arc-conti nent suturing), Mississippian-Pennsylvanian intraplate margin, Pennsylvanian-Permian Ancestral Rockies orogeny (Ouachita-Marathon continental suturing), Permian-Triassic Sonoma orogeny (arc-continent suturing), Triassic-Jurassic continental-margin magmatic arc, Late Jurassic Nevadan orogeny (arc-arc suturing), latest Jurassic-Late Cretaceous continentalmargin magmatic arc, latest Cretaceous-Eocene Laramide orogeny, Oligocene ignimbrite flareup, and Miocene-Holocene triple-junction migration, transform boundary, and regional exten sion of the Great Basin. The integrated result of sequential superposition of the actualistic models produces a reasonable representation of the complexity of the study area. The discipline of applying actualistic models to the evolution of this continental margin provides new insights and forces one to consider new implications of the models. The complexity of the tectonic history of this continental margin argues against simplistic general models for the growth of continental crust.

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Section: Oligocene Ignimbrite Flare-upmentioning

confidence: 93%

Section: Latest Cretaceous-eocene Laramide Orogenymentioning

confidence: 95%

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Phanerozoic Tectonic Evolution of Central California and Environs

Ingersoll

1997

International Geology Review

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“…Over several decades, many attempts have been made to link Late Cretaceous-Tertiary (i.e., Laramide) and Middle Tertiary magmatism in western North America to the subduction history along the Farallon-North American plate boundary (e.g., Coney and Reynolds, 1977;Keith, 1978;Damon et al, 1981Damon et al, , 1983Humphries, 2009). Specifi cally, the westward sweep of magmatism indicated by exposures of the Middle Tertiary ignimbrite fl are-up in the western United States (e.g., Henry et al, 2010) has been linked to patterns of delamination and/ or rollback of the subducted Farallon slab.…”

Section: A More Regional Perspectivementioning

confidence: 99%

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McDowell

McIntosh

2012

Geosphere

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The ~400,000 km 2 calc-alkalic Sierra Madre Occidental volcanic fi eld is the largest component of the Tertiary ignimbrite fl are-up of western North America. Laser-fusion 40 Ar/ 39 Ar geochronology of sanidine and anorthoclase from ignimbrites sampled within three areas of concentrated geologic mapping in the Mexican states of Chihuahua and Durango provides the fi rst examination of fi ne-scale temporal fl uctuations within this signifi cant area of the ignimbrite fl are-up. Overall, the 112 40 Ar/ 39 Ar ages range from 28 to 46 Ma, with a separate group near 24 Ma. The oldest ages (40-46 Ma, with a strong cluster at 44-46 Ma) are found only along the eastern margin of the fi eld. The predominant age concentration (28-36 Ma) is found across two east-west traverses of the volcanic fi eld that are separated by 500 km. Within this interval, there are strong concentrations at 28-30 Ma, ca. 33 Ma, and 35-36 Ma in the northern traverse, and at 30-31 Ma and at 31.5 Ma in the southern traverse. A cluster of ages near 24 Ma is present in the western part of both traverses. Ignimbrite sequences of similar age are oriented in belts generally parallel to the axis of the Sierra Madre Occidental volcanic fi eld. The belts partly overlap but are progressively younger toward the west. This geographic pattern fi ts with numerous studies that relate the position of arc magmatism to the delamination/rollback of the subducted Farallon slab. However, a more diffi cult challenge is to reconcile a pattern of discrete, brief (~2 m.y.) and intense episodes of magmatism to behavior of the Farallon plate.

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“…In both cases, the involvement of K 2 O-rich crustal materials in the magma source for the eastern region is considered a likely explanation for the variation. At a more regional scale, the potassium contents in Cretaceous and Tertiary magmatic rocks of southwestern North America are believed to reflect the depth of the subducted oceanic slab beneath a corresponding center of volcanic activity (Keith, 1978(Keith, , 1982. The K 2 O variation also was coupled with relatively larger strontium initial ratios to the east (e.g., Gromet and Silver, 1987;Silver and Chappell, 1988;Valencia-Moreno et al, 2001), which may invoke the contribution of an older and more isotopically evolved continental lithosphere.…”

Section: Characteristics Of the Study Area And Goals Of The Studymentioning

confidence: 97%