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Influence of San Gabriel submarine canyon on narrow-shelf sediment dynamics, southern California

Marine Geology

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DOI: 10.1016/0025-3227(80)90141-3

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Abstract

Variations in the concentration of total suspended particulate matter (TSM) collected 1 m above bottom, changes in vertical profiles of light transmission, and substrate textural patterns reveal a corridor for preferential sediment transport on San Pedro continental shelf, California. During the winter, this corridor, designated the preferential transport corridor (PTC), is defined by higher concentrations of TSM relative to the rest of the shelf and extends for 10-15 km from the inner shelf to the head of San Gabriel Submarine Canyon. Vertical profiles of light transmission within the PTC suggest density stratification throughout the water column and apparent mixing in the upper 15-20 m of water column on either side of the PTC. The PTC is not as fully developed during the summer. Excursions in isopleths of substrate textural variables perpendicular to isobaths in the PTC suggest that although the PTC is seasonally episodic, it recurs regularly over a longer period.

 

A conceptual model attributes the PTC to modification of shelf circulation patterns by San Gabriel Canyon. Surface waves diverge over the canyon head resulting in differential wave set up at the shore face. This forces back turbid nearshore water for a distance of a few kilometers toward the canyon. At some point on the shelf, seaward nearshore flow overlaps offshore currents generated or modified by internal waves focused onto the shelf by the canyon and/or turbulent eddies produced by flow separation in currents moving across the canyon axis. At times, these subtle processes overprint tidal and wind-driven currents and thereby create the PTC. The model suggests that canyons heading several kilometers from shore can have a regulatory effect on narrow-shelf sediment dynamics.

Geospatial Extents

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Influence of San Gabriel submarine canyon on narrow-shelf sediment dynamics, southern California
Series title:
Marine Geology
DOI:
10.1016/0025-3227(80)90141-3
Volume
34
Issue:
1-2
Year Published:
1980
Language:
English
Publisher:
Elsevier
Contributing office(s):
Coastal and Marine Geology Program
Description:
18 p.
First page:
61
Last page:
78
Country:
United States
State:
California
Other Geospatial:
San Gabriel Submarine Canyon
Online Only (Y/N):
N
Additional Online Files(Y/N):
N