Development of slope valleys in the glacimarine environment of a complex subduction zone, Northern Gulf of Alaska

Special Papers of the Geological Society of London
By: , and 

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Abstract

Morphological, seismic-reflection, and sedimentological evidence indicates that glacial ice tongues cut large sea valleys into the Gulf of Alaska continental shelf during the Pleistocene. During the Holocene, glacially-derived sediments from the Copper River and other meltwater streams have been prograding seaward across the shelf, covering the glacial and glacimarine upper Yakataga diamicts that blanketed the shelf and accumulated on the upper slope seaward of the sea valleys during the Pleistocene. GLORIA imagery near Middleton Island provides a new perspective on the glacimarine depositional environment on the continental slope in a collision zone between the Pacific and North American plates. Southwest of Middleton Island, along the subduction margin, sinuous valleys funnel sediment around shelf-edge-parallel, subduction-created, anticlinal ridges that have deflected and locally trapped glacimarine sediment. The slope south and southeast of Middleton Island where oblique convergence occurs, is incised by dendritic, erosional gulley systems, contains no compressional ridges, and thus, the apparently active sediment pathways to the trench are unrestricted. However, below the sea valley mouths, apparently both glacial and glacimarine sediments blanket the upper slope, covering any dendritic gulley systems that may have formed during or since the Pleistocene low stands of sea level.

Study Area

Publication type Book chapter
Publication Subtype Book Chapter
Title Development of slope valleys in the glacimarine environment of a complex subduction zone, Northern Gulf of Alaska
Series title Special Papers of the Geological Society of London
DOI 10.1144/GSL.SP.1990.053.01.08
Volume 53
Year Published 1990
Language English
Publisher Geological Society of London
Description 15 p.
Larger Work Type Book
Larger Work Subtype Monograph
Larger Work Title Glacimarine environments: Processes and sediments
First page 139
Last page 153
Country United States
State Alaska
Other Geospatial Gulf of Alaska, Middleton Island
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