Plate tectonic evolution of the Cascades arc-subduction complex
Robert A. Duncan, LaVerne D. Kulm, 1989. "Plate tectonic evolution of the Cascades arc-subduction complex", The Eastern Pacific Ocean and Hawaii, E. L. Winterer, Donald M. Hussong, Robert W. Decker
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The geological development of the Pacific Northwest margin of North America from earliest Tertiary time to the present has been dominated by the effects of plate convergence. During this period the North America Plate has moved slowly but increasingly westward as the Atlantic basin widened, and has collided with eastward-moving oceanic plates formed in the Pacific basin. Much of the geologic record of this collision has been removed by subduction of the oceanic plate beneath North America, with the exception of limited quantities of accreted and deformed oceanic rocks, and has been covered by younger volcanic and sedimentary material on the continent. Thus, a description of the plate tectonic evolution of this active continental margin is speculative and based on assumptions and inferences from the fragmentary geological evidence. This is certainly a problem common to all convergent margins, but many factors in the convergence history of this plate boundary make it unusual and offer the promise of isolating a few of the variables in subduction-related processes.
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This new synthesis includes a section on plate kinematics, documenting the basis for a new interpretation of the magnetic anomaly patterns. It also includes: six chapters on various aspects of tectonics, petrologic characteristics, and hydrothermal processes of active ridges from the Galapagos Rift to the Juan de Fuca Ridge; a section on mid-plate volcanism, including the Hawaii-Emperor chain; five chapters on various aspects of northeastern Pacific sedimentary regimes; and nine chapters on the geology of the Pacific continental margin from the Aleutians to Guatemala, seen from the perspective of marine geology. Three separate oversize plates illustrate the bathymetry of the northeast Pacific; two more on the same base show distribution of sediment samples and types and magnetic anomaly data and tectonic interpretations; and others include a synthesis of the geology and bathymetry of the Hawaiian Islands, details of bathymetry along parts of the East Pacific Rise, and a major seismic profile across the Pacific margin of Guatemala.