During June 1998 and April 1999, the U.S. Geological Survey (USGS) conducted two research cruises in the northern Gulf of Mexico to acquire high-resolution seismic reflection data across the upper and middle continental slope as part of an investigation of the seismic character, distribution, and potential effects of naturally-occurring marine gas hydrates and related free gas within the gas hydrate stability zone. Over 1600 km of two-dimensional multichannel seismic reflection profiles were acquired during these two cruises. The specific objectives of this investigation are (a) to produce high-resolution images of the gas hydrate stability zone; (b) to study the distribution and character of potential seafloor failures and their relationship to known and inferred gas hydrate deposits; (c) to look at systematic variations in subsurface structure in gas hydrate and non-hydrate areas; and (d) to estimate, if possible, the amounts of hydrates present within the gas hydrate stability zone. The multichannel profiles provide high-quality images with approximately 5 meters of vertical resolution and up to 2 km of penetration. This report gives an overview of the acquisition and data processing of the multichannel seismic reflection profiles and provides references and links to reports with more detailed information. Geologic interpretations of these seismic profiles regarding gas hydrate occurrence and distribution within the study areas of this investigation are given in Hart and others (2002).
Hart, Patrick E., Cooper, Alan K., and Twichell, David C., 2005, GOM98SHTALLG.SHP - Locations of All Shotpoints, USGS Cruise M1-98-GM: Open-File Report 2005-1071, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Science Center, Woods Hole, MA.This is part of the following larger work.Online Links:
Twichell, D.C., Cross, V.A., Paskevich, V.F., Hutchinson, D.R., Winters, W.J., and Hart, P.E., 2005, GIS of selected geophysical and core data in the northern Gulf of Mexico continental slope collected by the U.S. Geological Survey: Open-File Report 2005-1071, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Science Center, Woods Hole, MA.Online Links:
This is a Vector data set. It contains the following vector data types (SDTS terminology):
Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.000000. Longitudes are given to the nearest 0.000000. Latitude and longitude values are specified in Decimal degrees.
The horizontal datum used is North American Datum of 1983.
The ellipsoid used is Geodetic Reference System 80.
The semi-major axis of the ellipsoid used is 6378137.000000.
The flattening of the ellipsoid used is 1/298.257222.
Sequential unique whole numbers that are automatically generated.
Coordinates defining the features.
Character string defining the line number
| Range of values | |
|---|---|
| Minimum: | 15 |
| Maximum: | 10769 |
| Units: | integer count |
| Resolution: | 1 |
| Range of values | |
|---|---|
| Minimum: | 28.02689 |
| Maximum: | 28.65736 |
| Units: | decimal degrees |
| Resolution: | .00001 |
| Range of values | |
|---|---|
| Minimum: | -89.94109 |
| Maximum: | -88.99771 |
| Units: | decimal degrees |
| Resolution: | .00001 |
| Range of values | |
|---|---|
| Minimum: | 211505.38 |
| Maximum: | 303918.00 |
| Units: | meters |
| Resolution: | .01 |
| Range of values | |
|---|---|
| Minimum: | 3131736.77 |
| Maximum: | 3120741.85 |
| Units: | meters |
| Resolution: | .01 |
650-329-5160 (voice)
650-329-5190 (FAX)
hart@usgs.gov
This GIS overlay is a component of the U.S. Geological Survey, Woods Hole Field Center's, Gulf of Mexico GIS database. The Gulf of Mexico GIS database is intended to organize and display USGS held data and provide on-line (WWW) access to the data and/or metadata.
Person who carried out this activity:
(508) 548-8700 x2251 (voice)
(508) 457-2310 (FAX)
vatnipp@usgs.gov
Data sources produced in this process:
Hart, P.E., Cooper, A.K., Twichell, D., Lee, M., and Agena, W., 2002, High-resolution multichannel seismic-reflection data acquired in the northern Gulf of Mexico, 1998-99: Open-File Report 02-368, U.S. Geological Survey, Coastal and Marine Geology Program, Western Coastal and Marine Geology, Menlo Park, CA.Online Links:
Cooper, Alan, Hart, Patrick, and Pecher, Ingo, 1998, Cruise Report for a Seismic Investigation of Gas Hydrates in the Mississippi Canyon Region, Northern Gulf of Mexico - Cruise M1-98-GM: Open-File Report 98-506, U.S. Geological Survey, Coastal and Marine Geology Program, Western Coastal and Marine Geology, Menlo Park, CA.Online Links:
No additional checks for topological consistency were performed on this data set. No duplicate features are present.
Are there legal restrictions on access or use of the data?
- Access_Constraints: None
- Use_Constraints:
- Public domain data from the U.S. Government are freely redistributable with proper metadata and source attribution. Please recognize the U.S. Geological Survey (USGS) as the source of this information.
(508) 548-8700 x2266 (voice)
(508) 457-2310 (FAX)
dtwichell@usgs.gov
Downloadable Data
Although this data set has been used by the U.S. Geological Survey (USGS), no warranty, expressed or implied, is made by the USGS as to the accuracy of the data and/or related materials. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the USGS in the use of these data or related materials. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
| Data format: | The SHP file contains the geospatial data. The SHX file contains the index of the geospatial data. The DBF file contains the attribute data in dBase format. The PRJ file contains the coordinate system information (optional). The AVL file contains the legend information (optional). The SBN and SBX files contain the spatial index of the geospatial data (optional). The XML file contains the metadata describing the data set <data set name>.shp.xml. An ASCII version of the metadata file. A browse graphic showing the data layer coverage and extent (optional). in format SHP (version 3.3) ESRI Shapefile Format Size: 0.101 |
|---|---|
| Network links: |
<http://pubs.usgs.gov/of/2005/1071/data/seismic/1998/nav/gom98shtallg.zip> |
| Media you can order: |
DVD-ROM
(Density 4.75
Gbytes)
(format UDF)
|
These data are available in Environmental Systems Research Institute (ESRI) shapefile format. The user must have ArcGIS® or ArcView® 3.0 or greater software to read and process the data file. In lieu of ArcView or ArcGIS, the user may utilize another GIS application package capable of the importing data. A free data viewer, arcexplorer, capable of displaying the data is available from ESRI at www.esri.com.
(508) 548-8700 x2266 (voice)
(508) 457-2310 (FAX)
