Gulf of Alaska continental slope morphology: Evidence for recent trough mouth fan formation

Glaciated continental shelves are host to numerous morphologic features that help understand past glacier dynamics. Southeastern Alaska is home to the St. Elias mountains, an active orogen that also hosts temperate marine glaciers. During glacial periods ice streams advance across the continental sh...

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Published in:Geochemistry, geophysics, geosystems : G3 geophysics, geosystems : G3, 2015-01, Vol.16 (1), p.165-177
Main Authors: Swartz, John M., Gulick, Sean P. S., Goff, John A.
Format: Article
Language:English
Subjects:
Basins
continental margin
Continental margins
Continental shelves
Continental slope
cross-shelf troughs
Geomorphology
Glaciation
Glaciers
Glaciohydrology
Morphology
Mountains
Mouth
paleo-ice streams
sedimentary processes
Sediments
Shelves
Slopes
Soil erosion
trough-mouth fans
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Summary:Glaciated continental shelves are host to numerous morphologic features that help understand past glacier dynamics. Southeastern Alaska is home to the St. Elias mountains, an active orogen that also hosts temperate marine glaciers. During glacial periods ice streams advance across the continental shelf, carving shelf‐crossing troughs that reach the shelf edge. We use high‐resolution multibeam data to develop the relationship between the Yakutat and Alsek Sea Valleys and the resulting continental slope morphology. The shelf and slope geomorphology can be divided into statistical groupings that relate to the relative balance of erosion and deposition. Our analysis indicates that only the Yakutat system has been able to build an incipient trough‐mouth fan. The extreme sediment supply from this region was able to overwhelm the steep initial topography of the transform margin while further to the east sediment slope‐bypass dominates. This analysis provides an extreme end member to existing studies of temperate glaciation along continental margins. The unique interplay between rapid uplift due to ongoing collision and the massive erosion caused by temperate glaciers provides for sedimentary flux far above most other systems. Key Points: The Gulf of Alaska is host to at least one immature trough mouth fan Glacial‐tectonic interactions provide large sediment supply needed to prograde a transform margin Trough mouth fan formation dependent on sediment supply
ISSN:1525-2027
1525-2027
DOI:10.1002/2014GC005594