Geologic control on the evolution of the inner shelf morphology offshore of the Mississippi barrier islands, northern Gulf of Mexico, USA

Continental Shelf Research
U.S. Geological Survey Northern GOM Hazards and Susceptibility Project, and the U.S. Army Corps of Engineers (USACE) Mississippi Coastal Improvement Project
By: , and 

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Abstract

Between 2008 and 2013, high-resolution geophysical surveys were conducted around the Mississippi barrier islands and offshore. The sonar surveys included swath and single-beam bathymetry, sidescan, and chirp subbottom data collection. The geophysical data were groundtruthed using vibracore sediment collection. The results provide insight into the evolution of the inner shelf and the relationship between the near surface geologic framework and the morphology of the coastal zone. This study focuses on the buried Pleistocene fluvial deposits and late Holocene shore-oblique sand ridges offshore of Petit Bois Island and Petit Bois Pass. Prior to this study, the physical characteristics, evolution, and interrelationship of the ridges between both the shelf geology and the adjacent barrier island platform had not been evaluated. Numerous studies elsewhere along the coastal margin attribute shoal origin and sand-ridge evolution to hydrodynamic processes in shallow water (<20 m). Here we characterize the correlation between the geologic framework and surface morphology and demonstrate that the underlying stratigraphy must also be considered when developing an evolutionary conceptual model. It is important to understand this near surface, nearshore dynamic in order to understand how the stratigraphy influences the long-term response of the coastal zone to sea-level rise. The study also contributes to a growing body of work characterizing shore-oblique sand ridges which, along with the related geology, are recognized as increasingly important components to a nearshore framework whose origins and evolution must be understood and inventoried to effectively manage the coastal zone.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Geologic control on the evolution of the inner shelf morphology offshore of the Mississippi barrier islands, northern Gulf of Mexico, USA
Series title Continental Shelf Research
DOI 10.1016/j.csr.2015.04.008
Volume 101
Year Published 2015
Language English
Publisher North Pacific Marine Science Organization
Publisher location New York, NY
Contributing office(s) St. Petersburg Coastal and Marine Science Center
Description 12 p.
First page 59
Last page 70
Online Only (Y/N) N
Additional Online Files (Y/N) N
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