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Open-File Report 03-271

FGDC FORMAL SEISMIC METADATA

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Identification_Information:
Citation:
Citation_Information:
Originator: Karynna Calderon
Originator: Shawn V. Dadisman
Originator: James G. Flocks
Originator: Dana S. Wiese
Originator: Jack L. Kindinger
Publication_Date: 2003
Title:
Archive of Chirp Seismic Reflection Data Collected During USGS Cruises 01SCC01 and 01SCC02, Timbalier Bay and Offshore East Timbalier Island, Louisiana, June 30 - July 9 and August 1 - 12, 2001
Geospatial_Data_Presentation_Form: Seismic Reflection Profile Section
Series_Information:
Series_Name: U.S. Geological Survey Open-File Report
Issue_Identification: 03-271
Publication_Information:
Publication_Place: St. Petersburg, FL
Publisher: U.S. Geological Survey
Description:
Abstract:
This archive consists of two-dimensional marine seismic reflection profile data collected in Timbalier Bay and in the Gulf of Mexico offshore East Timbalier Island, Louisiana. These data were acquired in June, July, and August of 2001 aboard the R/V G.K. Gilbert. Included here are data in a variety of formats including binary, American Standard Code for Information Interchange (ASCII), Hyper Text Markup Language (HTML), Portable Document Format (PDF), Rich Text Format (RTF), Graphics Interchange Format (GIF) and Joint Photographic Experts Group (JPEG) images, and shapefiles. Binary data are in Society of Exploration Geophysicists (SEG) SEG-Y format and may be downloaded for further processing or display. Reference maps and GIF images of the profiles may be viewed with a web browser. The Geographic Information Systems (GIS) information provided is compatible with Environmental Systems Research Institute (ESRI) GIS software.
Purpose:
Marine seismic reflection data are used to image and map sedimentary and structural features of the seafloor and subsurface. These data are useful in mapping stratigraphy and in assessing other submarine geologic characteristics and features. These data were collected as part of a Louisiana Sand Resources Study done in cooperation with the University of New Orleans, the U.S. Army Corps of Engineers, and the Louisiana Department of Natural Resources. This study is part of the U.S. Geological Survey (USGS) Subsidence and Coastal Change (SCC) project.
Supplemental_Information:
The USGS Center for Coastal and Watershed Studies team in St. Petersburg, Florida, assigns a unique identifier to all seismic data collected during each cruise or field activity. The method used to assign the identifier for the activity is as follows: YYPPP##, where YY stands for the last 2 digits of the year in which the fieldwork is conducted, PPP is a 3-letter abbreviation for the project the data are collected for, and ## is a 2-digit event tag that represents a discreet leg or time period of fieldwork. Here, for example, 01SCC01 tells us the data were collected in 2001 for the Subsidence and Coastal Change Project and that the data were collected during the first field activity for that project in that calendar year. The naming convention the center uses for each seismic line is as follows: yye###a, where yy is the last 2 digits of the year in which the data were collected, e is a 1-letter abbreviation for the equipment type (i.e. c for chirp and b for boomer), ### is a 3-digit number representing a specific track, and a is a 1-letter abbreviation representing the section of a line if recording was prematurely terminated.

Seismic reflection profiles are acquired by means of an acoustic source (usually generated electronically) and hydrophone or receiver arrays. Both elements are typically towed in the water behind a survey vessel. The sound source emits a short acoustic pulse, or shot, that propagates through the water and sediment column. The acoustic energy is reflected at density boundaries (such as the seafloor or sediment layers beneath the seafloor) and detected at the receiver. This process is repeated at intervals ranging between 100 milliseconds (ms) and 1 second (s) depending on the seismic source employed. In this way, a two-dimensional vertical image of the geologic structure beneath the ship track can be interpreted.

The chirp system uses a signal of continuously varying frequency. The seismic source employed consisted of an EdgeTech X-Star SB-424 tow fish running Triton Elics FSSB software. The tow fish is routinely flown 2 - 5 m above the seafloor. Therefore, water depths shown on the chirp profiles are relative to the depth of the tow fish and not to sea level. Furthermore, the raising or lowering of the tow fish during a survey (to avoid obstacles or follow relief) produces a relative shift in the multiple reflections seen in the profile, which may be confused as a geologic feature. Any elevation change of the tow fish is recorded in the crew logbook. The fish was towed about 10 m behind the Global Positioning System (GPS) antenna, and no correction for this offset has been made. The sample frequency of the data was 25 kilohertz (kHz). All tracklines were recorded to 32 ms. Based on survey speeds of 3.5 - 4 knots and a shot rate of 0.125 s, the shot spacing was about 0.25 m. For each recorded shot of the chirp data, 3 channels of trace data were collected. Channel 3 is the "real," or in-phase component of the signal, channel 2 is the "imaginary," or quadrative component of the signal, and channel 1 is the "envelope," or product of channels 2 and 3. Only channel 1 was used to produce the profiles presented here. However, all channels are included in the SEG-Y data files. No SEG-Y data exists for tracklines 01c003, 01c011, 01c012, or 01c027. The original trace files for tracklines 01c001, 01c002, 01c009, 01c010, 01c015, 01c016, 01c019, 01c029, 01c031, 01c047, 01c048, 01c049, and 01c068 were broken up into 2 or more new trace files (i.e. 01c001 became 01c001a and 01c001b) because the original total number of traces exceeds the maximum allowed by the processing system.

Seismic data were stored in SEG-Y format, which is a standard digital format that can be read and manipulated by most seismic processing software packages. The SEG-Y file format includes a 3,200-byte descriptive header that contains detailed information regarding the data acquisition and processing parameters. All data presented here are stored in SEG-Y, integer, Motorola format. The SEG-Y data files are too large to fit on one Digital Versatile Disc (DVD), so they have been distributed onto four discs with the SEG-Y data files for lines 01c001a - 01c019b on Disc 1, lines 01c020 - 01c040 on Disc 2, lines 01c041 - 01c060 on Disc 3, and lines 01c061 - 01c081 on Disc 4. The SEG-Y formatted trace data files have a .TRA extension. Additional recording parameters for each seismic data file can also be found in the .PAR file associated with each .TRA file. However, the .PAR and .pln files are only needed to process or display the data with Triton Elics Delph Seismic software.

Differential GPS (DGPS) navigation was provided to the acquisition system every second by a WAAS/Beacon DGPS receiver. The accuracy of this receiver is within 5 m. However, the data required some editing to remove spurious data values. The edited results were used to generate the trackline maps presented here. The navigation data have not been corrected to reflect the 10-m offset between the shotpoint and the GPS antenna. Position fixes for every 1,000 shots and for the starts of lines are also provided as an aid for registering of the data after plotting. All navigation files are stored as flat ASCII text files.

The trackline maps provided in this archive are in geographic projection. They were created using ESRI GIS software ArcView 3.2, exported to Adobe Illustrator for further editing, and saved for the web in JPEG format. These JPEG images are viewable with a web browser. Also included on each disc is the ESRI ArcView project and shapefiles used to create the trackline maps presented here. The project is compatible with ArcView 3.x (Unix or Windows) and ArcGIS 8.x (Windows). The shapefiles can also be viewed using public domain software ArcExplorer 2.0 (Windows) and 4.0 (Windows, Unix, Linux), which can currently be downloaded from the ESRI website at <http://www.esri.com/software/arcexplorer/index.html>.

Field Activity Collection System (FACS) logs are available in both HTML and Rich Text Format. Scanned versions of the handwritten logbooks are also provided as Adobe Acrobat PDF files.

Also included on each disc are example Seismic Unix (SU) scripts that allow the user to strip off navigation fixes from the SEG-Y headers, along with a fix for every 1,000 shots, and produce a gained GIF image of each profile. These images can then be displayed using a variety of shareware programs such as ImageMagick (Unix or Linux) or a web browser.

Time_Period_of_Content:
Time_Period_Information:
Range_of_Dates/Times:
Beginning_Date: 20010630
Ending_Date: 20010812
Currentness_Reference: Data collection interval
Status:
Progress: Complete
Maintenance_and_Update_Frequency: None planned
Spatial_Domain:
Bounding_Coordinates:
West_Bounding_Coordinate: -90.395033
East_Bounding_Coordinate: -90.182895
North_Bounding_Coordinate: 29.143576
South_Bounding_Coordinate: 28.946107
Keywords:
Theme:
Theme_Keyword_Thesaurus: None
Theme_Keyword: marine seismic reflection
Theme_Keyword: chirp
Theme_Keyword: 01SCC01
Theme_Keyword: 01SCC02
Theme_Keyword: SEG-Y
Theme_Keyword: Subsidence and Coastal Change Project
Theme_Keyword: Louisiana Sand Resources Study
Theme_Keyword: beach renourishment
Place:
Place_Keyword_Thesaurus: None
Place_Keyword: Louisiana
Place_Keyword: Gulf of Mexico
Place_Keyword: Timbalier Bay
Place_Keyword: East Timbalier Island
Place_Keyword: Port Furchon
Access_Constraints: None. These data are held in the public domain.
Use_Constraints:
The U.S. Geological Survey requests to be acknowledged as the originator of the data in future products or derivative research.
Point_of_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Jack L. Kindinger
Contact_Organization: U.S. Geological Survey
Contact_Position: Oceanographer
Contact_Address:
Address_Type: mailing address
Address: 600 Fourth Street South
City: St. Petersburg
State_or_Province: FL
Postal_Code: 33701
Country: USA
Contact_Voice_Telephone: (727) 803-8747, ext. 3018
Contact_Electronic_Mail_Address: jkindinger@usgs.gov
Browse_Graphic:
Browse_Graphic_File_Name: DVD/maps/all.jpg
Browse_Graphic_File_Description:
Trackline map of all chirp seismic reflection data collected during USGS Cruises 01SCC01 and 01SCC02. These data were collected in Timbalier Bay and in the Gulf of Mexico offshore of East Timbalier Island, Louisiana, in June, July, and August of 2001. This map is in geographic projection and was created at a scale of 1:200,000 using ESRI GIS software ArcView 3.2. The image was exported to Adobe Illustrator for further editing and saved for the web in JPEG format. The USGS is not the originator of all layers used in creating the maps presented in this archive. The rivers layer is a Louisiana Oil Spill Coordinator's Office (LOSCO) data set derived from ESRI/Geographic Data Technology, Inc. (GDT) data that were in turn derived from Bureau of the Census TIGER/Line files. The water bodies layer is also a LOSCO data set derived from ESRI/GDT data.
Browse_Graphic_File_Type: JPEG
Browse_Graphic:
Browse_Graphic_File_Name: DVD/maps/area_a.jpg
Browse_Graphic_File_Description:
Trackline map of chirp seismic reflection data collected in Area A of Timbalier Bay, Louisiana (refer to Area A of the full survey map), during USGS Cruises 01SCC01 and 01SCC02 in June, July, and August of 2001. This map is in geographic projection and was created at a scale of 1:100,000 using ESRI GIS software ArcView 3.2. The image was exported to Adobe Illustrator for further editing and saved for the web in JPEG format. The USGS is not the originator of all layers used in creating this map. The rivers layer is a LOSCO data set derived from ESRI/GDT data that were in turn derived from Bureau of the Census TIGER/Line files. The water bodies layer is also a LOSCO data set derived from ESRI/GDT data.
Browse_Graphic_File_Type: JPEG
Browse_Graphic:
Browse_Graphic_File_Name: DVD/maps/area_b.jpg
Browse_Graphic_File_Description:
Trackline map of chirp seismic reflection data collected in Area B of the Gulf of Mexico offshore of East Timbalier Island, Louisiana (refer to Area B of the full survey map), during USGS Cruises 01SCC01 and 01SCC02 in June, July, and August of 2001. This map is in geographic projection and was created at a scale of 1:100,000 using ESRI GIS software ArcView 3.2. The image was exported to Adobe Illustrator for further editing and saved for the web in JPEG format. The USGS is not the originator of all layers used in creating this map. The rivers layer is a LOSCO data set derived from ESRI/GDT data that were in turn derived from Bureau of the Census TIGER/Line files. The water bodies layer is also a LOSCO data set derived from ESRI/GDT data.
Browse_Graphic_File_Type: JPEG
Data_Set_Credit:
Funding and/or support for this study were provided by the Coastal and Marine Geology Program (CMGP) of the USGS, the University of New Orleans, the U.S. Army Corps of Engineers, and the Louisiana Department of Natural Resources. We thank boat captains Dave Bennett of Eckerd College in St. Petersburg, Florida, and Keith A. Ludwig and Richard W. Young of the USGS in St. Petersburg, Florida, for their assistance in data collection. We also thank reviewers Terence N. Edgar of the USGS in St. Petersburg, Florida, and Patricia A. Metz of the USGS in Tampa, Florida, whose comments improved this document.
Native_Data_Set_Environment: SEG-Y

Data_Quality_Information:
Attribute_Accuracy:
Attribute_Accuracy_Report:
The validity or accuracy of marine seismic reflection profiles is highly qualitative and depends on equipment and operating condition variables. Visual inspection of the images rendered from the data did not show any major anomalies. The original trackline 01c001 was divided into 01c001a and b; 01c002 into 01c002a, b, and c; 01c009 into 01c009a, b, and c; 01c010 into 01c010a and b; 01c015 into 01c015a and b; 01c016 into 01c016a and b; 01c019 into 01c019a and b; 01c029 into 01c029a, b, and c; 01c031 into 01c031a and b; 01c047 into 01c047a, b, and c; 01c048 into 01c048a, b, and c; 01c049 into 01c049a and b; and 01c068 into 01c068a and b because the original total number of traces exceeds the maximum allowed by the processing system.
Logical_Consistency_Report:
These data sets are from two cruises with consistent instrument calibrations.
Completeness_Report:
These data are collected along tracklines (2D). Therefore, data are inherently incomplete. Geologic details between lines must be inferred. No digital data exists for tracklines 01c003, 01c011, 01c012, or 01c027.
Positional_Accuracy:
Horizontal_Positional_Accuracy:
Horizontal_Positional_Accuracy_Report:
The positional accuracy was determined with a WAAS/Beacon DGPS receiver. The accuracy of this receiver is within 5 m. The DGPS data were fed to a navigation computer running Hypack software, which converted the data to Zone 15 Universal Transverse Mercator (UTM) coordinates. The UTM string was fed every second to the Delph Seismic acquisition system, and navigation fixes were recorded in the SEG-Y headers. However, the tow fish was towed about 10 m behind the GPS antenna, and no correction for this offset has been made.
Vertical_Positional_Accuracy:
Vertical_Positional_Accuracy_Report: Chirp data depth is relative to the depth of the tow fish.
Lineage:
Process_Step:
Process_Description:
Chirp processing: Raw SEG-Y data were processed with Seismic Unix to produce the GIF seismic profiles included in this report. A representative data processing sequence consisted of: 1) Strip off channel 1 for each shot and convert to SU format 2) Automatic gain control 3) Postscript display 4) Convert Postscript to GIF format
Process_Date: 2002
Process_Step:
Process_Description:
Positional (navigation) data: As the seismic reflection data were acquired, the position of the vessel was continuously determined by a DGPS receiver. Positions were recorded approximately every second and written to the SEG-Y headers. The ASCII navigation and 1,000-shot interval navigation files were extracted from the SEG-Y headers using Seismic Unix scripts.
Process_Date: 2002
Process_Step:
Process_Description:
Editing navigation: The ASCII navigation files were extracted from the SEG-Y headers and edited to remove spurious data points. The data were then processed using PROJ.4 freeware to convert Zone 15 UTMs to latitude and longitude and reformat the data for use with ESRI GIS software ArcView 3.2. Both sets of coordinates are provided for all lines.
Process_Date: 2002
Process_Step:
Process_Description:
Open-File preparation: No processing has been done to the SEG-Y data files provided on these discs. The data were displayed as 8-bit gray scale Postscript files using the Seismic Unix 'psimage' algorithm. The Postscript images were then converted to GIF images with ImageMagick.
Process_Date: 2002

Spatial_Data_Organization_Information:
Indirect_Spatial_Reference:
Horizontal X and Y locations (both UTMs and latitude and longitude) for each shot location are provided in ASCII position files, along with the time the shot was recorded in Greenwich Mean Time.

Spatial_Reference_Information:
Horizontal_Coordinate_System_Definition:
Geographic:
Latitude_Resolution: 0.000009
Longitude_Resolution: 0.000009
Geographic_Coordinate_Units: decimal degrees
Geodetic_Model:
Horizontal_Datum_Name: WGS84
Ellipsoid_Name: WGS84
Semi-major_Axis: 6378137 m
Denominator_of_Flattening_Ratio: 298.257

Entity_and_Attribute_Information:
Overview_Description:
Entity_and_Attribute_Overview:
Binary data file: Each profile is available as a binary file in Society of Exploration Geophysicists (SEG) SEG-Y format. A SEG-Y file consists of 1) a 3,200-byte file identification record of ASCII-formatted general information, 2) a 400-byte binary record with information such as sample rate and record length specific to the data set, and 3) multiple records, with three seismic reflection traces per record for chirp data. Each trace record is preceded by a 240-byte trace header containing information such as trace number and acquisition day and time specific to each trace. The trace data are represented as a time series of unitless 16-bit integer or 32-bit real numbers proportional to the reflection coefficient. The SEG-Y file is useful only if you have access to specialized software designed to process and display seismic reflection data. These SEG-Y files have a .TRA extension and range in size from 3.29 to 268 MB.
Entity_and_Attribute_Detail_Citation:
Barry, K.M., Cavers, D.A., and Kneale, C.W., 1975, Recommended standards for digital tape formats: Geophysics, v. 40, n.2, p. 344-352. Also available online at: <http://www.seg.org/publications/tech-stand/index_body.html>.
Entity_and_Attribute_Overview:
Graphic image file: Each profile is available as a GIF image. The trackline maps provided are JPEG images that contain hotlinks to the seismic profile images. The profiles range in size from 115 KB to 5.5 MB.

Distribution_Information:
Distributor:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Shawn V. Dadisman
Contact_Organization: U.S. Geological Survey
Contact_Position: Geologist
Contact_Address:
Address_Type: mailing address
Address: 600 Fourth Street South
City: St. Petersburg
State_or_Province: FL
Postal_Code: 33701
Country: USA
Contact_Voice_Telephone: (727) 803-8747, ext. 3029
Contact_Electronic_Mail_Address: sdadisman@usgs.gov
Contact_Instructions:
Data may be available on-line only by special arrangement with the distributor above.
Resource_Description: U.S. Geological Survey Open-File Report 03-271
Distribution_Liability:
This Digital Versatile Disc (DVD) publication was prepared by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, make any warranty, expressed or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed in this report, or represents that its use would not infringe privately owned rights. Reference therein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. Any views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.

Although all data published on these DVDs have been used by the USGS, no warranty, expressed or implied, is made by the USGS as to the accuracy of the data and related materials and/or the functioning of the software. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the USGS in the use of this data, software, or related materials.

Standard_Order_Process:
Digital_Form:
Digital_Transfer_Information:
Format_Name: SEG-Y
Format_Information_Content:
The SEG-Y standard format (Barry et al., 1975) consists of the following: a 3,600-byte reel identification header with the first 3,200 bytes consisting of an ASCII header block and a 400-byte binary header block that both include information specific to line and reel number, a trace data block that follows the reel identification header with the first 240 bytes of each trace block consisting of the binary trace identification header, and seismic data samples that follow the trace identification header.
File_Decompression_Technique: None
Transfer_Size: 14,800 MB
Digital_Transfer_Option:
Offline_Option:
Offline_Media: DVD
Recording_Format: UDF (Universal Disc Format)
Compatibility_Information: UNIX, LINUX, DOS, MAC
Digital_Form:
Digital_Transfer_Information:
Format_Name: ESRI project, shapefile, metadata
Format_Information_Content:
GIS project and layers used to create the trackline maps presented in this archive and associated metadata.
File_Decompression_Technique: unzip
Transfer_Size: 22.1 MB
Digital_Transfer_Option:
Online_Option:
Computer_Contact_Information:
Network_Address:
Network_Resource_Name: DVD/software/arc/arc.zip
Fees:
Available from the Denver Open-File Sales Department. Prices vary.
Ordering_Instructions:
Most open-file reports are available from USGS Information Services, Box 25286, Federal Center, Denver, CO 80225 (telephone: 1-888-ASK-USGS; email: infoservices@usgs.gov).
Technical_Prerequisites:
Use of SEG-Y data requires specialized seismic processing software, such as Unix or Linux-based public domain software Seismic Unix (SU) developed by the Colorado School of Mines Center for Wave Phenomena, which can be downloaded at <http://www.cwp.mines.edu/cwpcodes/index.html>.

Metadata_Reference_Information:
Metadata_Date: 20030528
Metadata_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Karynna Calderon
Contact_Organization: U.S. Geological Survey
Contact_Position: Geographer, Data Management Group
Contact_Address:
Address_Type: mailing address
Address: 600 Fourth Street South
City: St. Petersburg
State_or_Province: FL
Postal_Code: 33701
Country: USA
Contact_Voice_Telephone: (727) 803-8747, ext. 3143
Contact_Electronic_Mail_Address: kcalderon@usgs.gov
Metadata_Standard_Name: Content Standard for Digital Geospatial Metadata
Metadata_Standard_Version: FGDC-STD-001-1998

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