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The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 65 (1981)

Issue: 5. (May)

First Page: 907

Last Page: 907

Title: Structural Deformation in Northern Gulf of Alaska: Transition from Transform to Convergent Plate Motion: ABSTRACT

Author(s): Terry R. Bruns, Paul R. Carlson, George Plafker

Article Type: Meeting abstract


Multichannel seismic reflection data reveal the late Cenozoic structure along the continental margin in the northern Gulf of Alaska, where transform motion along the Queen Charlotte-Fairweather fault system gives way to convergent motion along the Aleutian Trench. The active trace of the Fairweather fault system lies generally near the outer shelf and upper slope but, south of Sitka, broad folds and associated faults in late Cenozoic strata seaward of the active trace may indicate additional fault splays beneath the continental slope. The intensity of deformation in these strata decreases to the north, and slope deposits seaward of the Fairweather fault are undeformed between Sitka and Cross Sound. Between Cross Sound and Icy Bay (the Yakutat segment), Eocene and younger helf strata are relatively undeformed along the continental slope. Late Cenozoic abyssal strata, which partly onlap the continental slope, are relatively undeformed except for local recent deformation seaward of Fairweather Ground. The observed structure along the Yakutat segment of the continental margin is more readily explained by strike-slip motion between the Yakutat segment and the Pacific plate than by oblique subduction of the Pacific plate as deduced from plate tectonic models. Between Icy Bay and Kayak Island (the Yakataga segment), northeast-trending faults and folds that deform Cenozoic strata beneath the shelf and slope suggest relatively continuous late Cenozoic convergence between the Yakataga and Yakutat segments of the continental margin. Thus, the Yakutat segment may ha e been coupled to the Pacific plate during much of the late Cenozoic.

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