Archive of Digitized Analog Boomer Seismic Reflection Data Collected from the Northern Gulf of Mexico: 1982, 1985, 1986, 1989, 1991, and 1992

The USGS-SPCMSC currently holds 13 major geophysical surveys from the northern Gulf of Mexico in its paper repository, while UNO holds seven. Over 2,000 line-kilometers (km) of data are available. Paper copies of data are difficult and expensive to duplicate and share with other facilities and cannot be analyzed using standard geographic information systems (GIS) and interpretative software. Conversion of this data into a usable digital format is necessary to archive the geologic information that otherwise might be lost, requiring additional redundant and expensive marine geophysical surveys. The USGS NGGDPP addresses the need to preserve, catalog, and provide access to geological and geophysical data for scientific research and economic development. In addition to the current efforts under the NGGDPP, four geophysical investigations from the 1980s and 1990s were previously archived through a preservation project in collaboration with the Bureau of Ocean Energy Management (Harrison and others, 2007; Sanford and others, 2009a, b, c). The USGS-SPCMSC scans its analog HRSP holdings using a large-format continuous scanner. The analog to digital conversion process used for this dataset is similar to the processes used previously in Harrison and others (2007) and Sanford and others (2009a, b, c). The digital files were converted into Tagged Image File Format (TIFF) for standard accessibility by raster image processors. The TIFF images of the seismic profiles were also converted into SEG-Y format. This standard non-proprietary format is the accepted industry standard for seismic data and can be accessed by all major seismic data processing and interpretation systems. Accompanying the HRSP are navigation and metadata files, which are generated for use in GIS, database and Internet Message Access Protocol (IMAP) services. Processed seismic profile images are also provided. The processed profiles provided in this data release are Portable Document Format (PDF) images that were created using Seismic Unix and/or ImageMagick software. The northern Gulf of Mexico is a passive continental margin, where minimal structural change to the shallow stratigraphy has occurred during the last few thousand years (Anderson and others, 2004). Therefore, subsurface data collected from this environment for the purposes of geologic assessment can be considered useful in perpetuity. The geologic information collected by the USGS in the northern Gulf of Mexico remains a valuable resource for sea floor and stratigraphic investigations, and is continuously revisited by researchers interested in Holocene and recent earth processes. For example, decades-old geologic data are commonly used in sediment resource studies in coastal Louisiana (Kindinger and others, 2001; Kulp and others, 2002; Rogers and others, 2009) and previously collected datasets across the Mississippi-Alabama shelf have been used in recent geologic-framework assessments (Roberts and others, 2004; Greene and others, 2007; Flocks and others, 2009). The seismic data were collected using a single-channel Huntec boomer/benthos hydrophone system with an Ocean Research Equipment (ORE) Geopulse power supply. The system consists of an electromechanical sound source mounted on a catamaran sled towed behind the vessel at the water surface. The signal emitted from the sound source is received by a 5 meter- (m) long hydrophone streamer towed alongside the sled. The received signal was recorded by a signal that passed through bandpass filters and was sent to a graphic recorder using a sweeping stylus to burn electrostatic paper. The seismic returns were printed onto paper rolls as two-dimensional profiles representing shots horizontally (time along track) and depth (two-way travel time). Geographic positioning of the system was collected using a long-range navigation (LORAN-C) system and annotated onto the paper copies.