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Tectonic evolution of the central U.S. Cordillera: A synthesis of the C1 and C2 Continent-Ocean Transects

By
J. B. Saleeby
J. B. Saleeby
Department of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California 91125
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R. C. Speed
R. C. Speed
Department of Geological Sciences, Northwestern University, Evanston, Illinois 60201
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M. C. Blake
M. C. Blake
U.S. Geological Survey, 345 Middlefield Road, Menlo Park, California 94025
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Published:
January 01, 1994

Abstract

The evolution of the North American continent and adjacent ocean basins in the central Cordillera of the western United States in Phanerozoic time was governed by three sequential tectonic regimes. The first included the creation of a passive margin during the latest Proterozoic to Early Cambrian (Stewart, 1976) and the removal of an unknown amount of sialic crust from the western margin of the continent. The second regime maintained a passive continental margin of western North America from Middle Cambrian to Triassic time, but permitted collisions of outboard terranes with the sialic margin in Mississippian and Permian-Triassic time (Speed, 1982; Dickinson and others, 1983). Since Triassic time, western North America, adjacent oceanic plates, and intervening microplates and other tectonic packets have existed in a regime of active margin tectonics (Hamilton, 1969; Coney and others, 1980; Saleeby, 1983; Saleeby and Busby-Spera, 1992) driven mainly by eastward subduction of oceanic lithosphere. This third and currently operating regime has been marked by diverse phenomena including subduction of oceanic lithosphere below the continent and phases of highly oblique convergence and suture-zone or intra-arc spreading, ridge-trench collision, growth of a continental arc, major foreland contraction and extension, and the accretion of displaced terranes to the sialic edge.

Corridors C1 and C2 of the Ocean-Continent Transect Program traverse all essential elements of the transition from Pacific plate oceanic crust to cratonal North America that have resulted from these three tectonic regimes. Figure 1 shows the locations of the corridors in relation to the major tectonic elements

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Contents

DNAG, Continent-Ocean Transect Series

Phanerozoic Evolution of North American Continent-Ocean Transitions

Robert C. Speed
Robert C. Speed
Department of Geological Sciences Northwestern University Evanston, Illinois 60208
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Geological Society of America
Volume
Summary volume
ISBN electronic:
9780813754437
Publication date:
January 01, 1994

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