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Anatomy and global context of the North American Cordillera

By
William R Dickinson
William R Dickinson
Department of Geosciences, University of Arizona, Tucson, Arizona 85721, USA
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Published:
June 01, 2009

The Cordillera of western North America occupies the central 5000 km of the circum-Pacific orogenic belt, which extends for 25,000 km along a great-circle path from Taiwan to the Antarctic Peninsula. The North American Cordillera is anomalous because dextral transform faults along its western flank have supplanted subduction zones, the hallmark of circum-Pacific tectonism, along much of the Cordilleran continental margin since mid-Cenozoic time. The linear continuity of the Cordilleran orogen terminates on the north in the Arctic region and on the south in the Mesoamerican region at sinistral transform faults of Mesozoic and Cenozoic age, respectively.

The Cordilleran margin of Laurentia was formed initially by rift breakup of the supercontinent Rodinia followed by development of the Neoproterozoic to early Paleozoic Cordilleran miogeocline along a passive continental margin, but it was modified in California and Mexico by Permian to Triassic transform truncation of Paleozoic tectonic trends. Late Paleozoic and Mesozoic accretion of oceanic island arcs and subduction complexes expanded the width of the Cordilleran orogen both before and after Triassic initiation of ancestral circum-Pacific subduction beneath the Cordilleran margin. Mesozoic to Cenozoic extensions and counterparts of Cordilleran accreted terranes extend southward into the Caribbean Antilles and northern South America.

The development of successive forearc and retroforeland basins accompanied the progress of Cordilleran orogenesis over time, and coeval Mesozoic to Cenozoic batholith belts reflect continuing plate consumption at subduction zones along the continental margin. The assembly of subduction complexes along the Cordilleran continental margin continued into Cenozoic time, but dextral strike slip along the Pacific flank of the Cordilleran orogen displaced elongate coastal segments of the orogen northward during Cenozoic time. In the United States and Mexico, Laramide breakup of the Cordilleran foreland during shallow slab subduction and crustal extension within the Basin and Range taphrogen also expanded the width of the Cordilleran orogen during Cenozoic time.

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GSA Memoirs

Backbone of the Americas: Shallow Subduction, Plateau Uplift, and Ridge and Terrane Collision

Suzanne Mahlburg Kay
Suzanne Mahlburg Kay
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Víctor A. Ramos
Víctor A. Ramos
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William R. Dickinson
William R. Dickinson
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Geological Society of America
Volume
204
ISBN print:
9780813712048
Publication date:
June 01, 2009

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