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Open-File Report 03-007

Bathymetry and Acoustic Backscatter of the Mid and Outer Continental Shelf, Head of De Soto Canyon, Northeastern Gulf of Mexico—Data, Images, and GIS

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shaded relief bathymetry

Shaded-relief bathymetry (color-coded by depth) of a portion of the 2002 multibeam sonar survey of the Head of De Soto Canyon region, Northeastern Gulf of Mexico. The width of the image is about 7.5 km.


Introduction

The mid to outer continental shelf off Mississippi-Alabama and off northwest Florida were the focus of U.S. Geological Survey (USGS) multibeam echosounder (MBES) mapping cruises in 2000 and 2001 (Figure 1), respectively. These areas were mapped to investigate the extent of "deep-water reefs" first suggested by Ludwig and Walton (1957). The reefs off Mississippi and Alabama were initially described in water depths of 60 to 120 m (Ludwig and Walton, 1957) but the 2000 mapping found reef and hardgrounds to be much more extensive than previously thought (Gardner et al., 2001). The persistent trend of reef-like features along the outer shelf of Mississippi-Alabama suggested the trend might continue along the northwest Florida mid and outer shelf so a MBES-mapping effort was mounted in 2001 to test this suggestion. It is critical to determine the accurate location, geomorphology, and types of the ridges and reefs that occur in this region to understand the Quaternary history of the area and to assess their importance as benthic habitats for fisheries.

The area known as the "Head of De Soto Canyon" is the large unmapped region between the 2000 and 2001 mapped areas (Figure 1). It was unknown whether the reefs of the Mississippi-Alabama shelf continue eastward into the head of De Soto Canyon and connect with the ridges and reefs mapped on the northwest Florida outer shelf. The existence of carbonate-cemented Quaternary to Holocene sandstones along the western wall of the head of De Soto Canyon (Shipp and Hopkins, 1978; Benson et al., 1997; W.W. Schroeder, personal commun., 2002) is of interest because of the potential benthic habitats they may represent. In the summer of 2002, the USGS, in cooperation with Minerals Management Service (MMS), the University of New Hampshire, and the University of New Brunswick, conducted a MBES survey of the Head of De Soto Canyon Region connecting the 2000 and 2001 mapped regions.

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Location map

Figure 1. Northeastern Gulf of Mexico location map showing the areas mapped in 2000 (yellow), 2001 (blue), and 2002 (green) using high-resolution multibeam echosounders (MBES).

This report provides the multibeam bathymetry and acoustic backscatter data, images, FGDC-compliant metadata, and a geographic information system (GIS) project of the 2002 survey of the Head of De Soto Canyon Region, Northeastern Gulf of Mexico.

Reports similar to this report publishing multibeam data of the 2000 and 2001 surveys can be found at,

2000 - Multibeam Mapping of the Pinnacles Region, Gulf of Mexico

2001 - Multibeam Mapping of the West Florida Shelf, Gulf of Mexico

For more information about the 2002 survey, see the Head of De Soto Canyon Multibeam Cruise Report, or visit our Pacific Seafloor Mapping Web site.

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References

Benson, D.J., Schroeder, W.W., and Shultz, A.W., 1997, Sandstone hardbottoms along the western rim of De Soto Canyon, northeast Gulf of Mexico: Gulf Coast Assoc. Geol. Soc. Trans., v. 47, p. 43-48.

Gardner, J.V., Dartnell, P., Sulak, K.J., , Calder, B., and Hellequin, L., 2001, Physiography and Late Quaternary-Holocene Processes of Northeastern Gulf of Mexico Outer Continental Shelf off Mississippi and Alabama: Gulf of Mexico Science v. 20, p. 132-157.

Ludwig, J.C., and Walton, W.R., 1957, Shelf-edge calcareous brominences in northeastern Gulf of Mexico: Bull. Amer. Assoc. Petroleum Geologists, v. 41, p. 2054-2101.

Shipp, R.L., and Hopkins, T.S., 1978, Physical and biological observations of the northern rim of the De Soto Canyon make from a research submersible: Northeast Gulf Science, v. 2, p. 113-121.


FGDC Metadata

The multibeam bathymetry and acoustic backscatter data are available in this report in two formats; ASCII XYZ and ESRI GRID. FGDC metadata is provided for each format and is available in three different forms, FAQ (Frequently Anticipated Questions), HTML, and text.

ASCII XYZ
ASCII-FAQ
ASCII-HTML
ASCII-TEXT
 
ESRI GRID
GRID-FAQ
GRID-HTML
GRID-TEXT

Disclaimer
These data not intended for navigational purposes.
Although these data have been used by the U.S. Geological Survey, U.S. Department of the Interior, these data and information are provided with the understanding that they are not guaranteed to be usable, timely, accurate, or complete. Users are cautioned to consider carefully the provisional nature of these data and information before using them for decisions that concern personal or public safety or the conduct of business that involves substantial monetary or operational consequences. Conclusions drawn from, or actions undertaken on the basis of, such data and information are the sole responsibility of the user.
Neither the U.S. Government nor any agency thereof, nor any of their employees, contractors, or subcontractors, make any warranty, express or implied, nor assume any legal liability or responsibility for the accuracy, completeness, or usefulness of any data, software, information, apparatus, product, or process disclosed, nor represent that its use would not infringe on privately owned rights.


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