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Accretion in the wake of terrane collision: The Neogene accretionary wedge off Kenai Peninsula, Alaska

Tectonics

By:
, , and
DOI: 10.1029/1998TC900021

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Abstract

Subduction accretion and repeated terrane collision shaped the Alaskan convergent margin. The Yakutat Terrane is currently colliding with the continental margin below the central Gulf of Alaska. During the Neogene the terrane's western part was subducted after which a sediment wedge accreted along the northeast Aleutian Trench. This wedge incorporates sediment eroded from the continental margin and marine sediments carried into the subduction zone on the Pacific plate. Prestack depth migration was performed on six seismic reflection lines to resolve the structure within this accretionary wedge and its backstop. The lateral extent of the structures is constrained by high-resolution swath bathymetry and seismic lines collected along strike. Accretionary structure consists of variably sized thrust slices that were deformed against a backstop during frontal accretion and underplating. Toward the northeast the lower slope steepens, the wedge narrows, and the accreted volume decreases notwith-standing a doubling of sediments thickness in the trench. In the northeasternmost transect, near the area where the terrane's trailing edge subducts, no frontal accretion is observed and the slope is eroded. The structures imaged along the seismic lines discussed here most likely result from progressive evolution from erosion to accretion, as the trailing edge of the Yakutat Terrane is subducting.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Accretion in the wake of terrane collision: The Neogene accretionary wedge off Kenai Peninsula, Alaska
Series title:
Tectonics
DOI:
10.1029/1998TC900021
Volume
18
Issue:
2
Year Published:
1999
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Tectonics
First page:
263
Last page:
277
Number of Pages:
15