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The AAPG/Datapages Combined Publications Database
AAPG Bulletin
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Along the eastern Aleutian Trench between Kayak and Sanak Islands, the trench, magmatic arc, and active Benioff zone define a modern convergent margin 13,000 km long. The structures developed during the past 10 to 15 m.y. show the deformation associated with subduction. Fore-arc basins have been formed on pre-Neogene rock that was presumably accreted, uplifted, and then locally depressed. Structures in the basins are compressional near the shelf edge and extensional farther toward the arc. The trench lower slope is underlain by rocks that are coeval with those in the fore-arc basin, but are deformed as a result of subduction. Despite a uniform convergence history, the margin has marked structural variations along strike that reflect local non-tectonic influences on struct ral style. The structure could be influenced by a variety of geologic variables such as sediment volumes on the slope, in the trench, and on the ocean crust, and perhaps by the morphology of the igneous ocean crust. Although we have not yet successfully reconciled all the effects of local variation on structural style, a comparative study of these styles and local features can help define kinematic processes associated with plate convergence.
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