Archive of Chirp Subbottom Profile Data Collected in 2015 from the Northern Chandeleur Islands, Louisiana

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Metadata:

Identification_Information:
Citation:
Citation_Information:
Originator: Arnell S. Forde
Originator: Nancy T. DeWitt
Originator: Jake J. Fredericks
Originator: Jennifer L. Miselis
Publication_Date: 20180116
Title:
Archive of Chirp Subbottom Profile Data Collected in 2015 from the Northern Chandeleur Islands, Louisiana
Geospatial_Data_Presentation_Form: multimedia presentation
Series_Information:
Series_Name: U.S. Geological Survey Data Release
Issue_Identification: doi:10.5066/F7668C5C
Publication_Information:
Publication_Place: St. Petersburg, Florida
Publisher:
U.S. Geological Survey - St. Petersburg Coastal and Marine Science Center
Online_Linkage: https://doi.org/10.5066/F7668C5C
Larger_Work_Citation:
Citation_Information:
Originator: Arnell S. Forde
Originator: Nancy T. DeWitt
Originator: Jake J. Fredericks
Originator: Jennifer L. Miselis
Publication_Date: 20180117
Title:
Chirp Subbottom Profile Data Collected in 2015 from the Northern Chandeleur Islands, Louisiana
Series_Information:
Series_Name: U.S. Geological Survey Data Series
Issue_Identification: 1077
Publication_Information:
Publication_Place: Reston, Virginia
Publisher: U.S. Geological Survey
Online_Linkage: https://doi.org/10.3133/ds1077
Description:
Abstract:
From September 14 to 28, 2015, the U.S. Geological Survey (USGS) conducted a geophysical survey to investigate the geologic controls on barrier island evolution and medium-term and interannual sediment transport along the sand berm constructed in 2011 (offshore, at the northern end of the Chandeleur Islands, Louisiana) as mitigation of the Deepwater Horizon oil spill. This investigation is part of a broader USGS project, which seeks to better understand barrier island evolution over medium time scales (months to years). This publication serves as an archive of unprocessed, digital chirp subbottom data, survey trackline map, navigation files, geographic information system (GIS) data, and formal Federal Geographic Data Committee (FGDC) metadata. Processed subbottom profile images are also provided. The archived trace data are in standard Society of Exploration Geophysicists (SEG) SEG Y revision 0 format (Barry and others, 1975) and may be downloaded and processed with commercial or public domain software such as Seismic Unix (SU). These data are available for viewing using GeoMapApp (http://www.geomapapp.org/) and Virtual Ocean (http://www.virtualocean.org/) multi-platform open source software. In addition, the SEG Y files can be downloaded from the USGS Coastal and Marine Geoscience Data System (http://cmgds.marine.usgs.gov).
Purpose:
To archive all digital chirp subbottom profile data and associated files collected during Field Activity Number 2015-331-FA. Additional survey and data details are available from the U.S. Geological Survey Coastal and Marine Geoscience Data System (CMGDS) at, https://cmgds.marine.usgs.gov/fan_info.php?fan=2015-331-FA.
Supplemental_Information:
All Chirp systems use a signal of continuously varying frequency; the system used during this survey produces high-resolution, shallow-penetration (typically less than 75-milliseconds [ms]) profile images of sub-seafloor stratigraphy. The towfish contains a transducer that transmits and receives acoustic energy and is typically towed 1–2 meters (m) below the sea's surface. As transmitted acoustic energy intersects density boundaries, such as the seafloor or sub-surface sediment layers, energy is reflected toward the transducer, received, and recorded by a PC-based seismic acquisition system. This process is repeated at regular intervals (for example, 0.125 seconds [s]) and returned energy is recorded for a specific duration (for example, 50 ms). In this way, a two-dimensional (2D) vertical image of the shallow geologic structure beneath the towfish is produced. The seismic source utilized during 2015-331-FA consisted of an EdgeTech SB-424 towfish running Discover version 3.51 acquisition software and towed approximately 3.6 m in front (port side) of the Global Positioning System (GPS) antenna. The data were acquired using a frequency sweep of 4–20 kilohertz (kHz), a 43 kHz sample frequency, and recording lengths that ranged between approximately 67 and 242 ms. Based on survey speeds of 3.5 knots, the shot spacing was approximately 0.450 m. The binary portion of the unprocessed seismic data is stored in SEG Y rev. 0, IBM float format, which is a standard digital format that can be read and manipulated by most seismic processing software packages; the first 3,200 bytes of the file header are in American Standard Code for Information Interchange (ASCII) format instead of Extended Binary Coded Decimal Interchange Code (EBCDIC) format. The SEG Y formatted trace files have a .sgy extension and may be downloaded and processed with commercial or public domain software such as Seismic Unix (SU) (Cohen and Stockwell, 2010). The printable profiles provided are chirp subbottom profile images that were processed using SU software. Survey Field Activity Collection System (FACS) and geophysical logs are also provided as supplemental information in the download file, 2015-331-FA_logs.zip.
Time_Period_of_Content:
Time_Period_Information:
Range_of_Dates/Times:
Beginning_Date: 20150914
Ending_Date: 20150928
Currentness_Reference: ground condition
Status:
Progress: Complete
Maintenance_and_Update_Frequency: None planned
Spatial_Domain:
Bounding_Coordinates:
West_Bounding_Coordinate: -88.877667
East_Bounding_Coordinate: -88.832981
North_Bounding_Coordinate: 30.072044
South_Bounding_Coordinate: 30.015653
Keywords:
Theme:
Theme_Keyword_Thesaurus: USGS Metadata Identifier
Theme_Keyword: USGS:038cad80-d0e8-4328-bc44-b1a1ed999a5c
Theme:
Theme_Keyword_Thesaurus: ISO 19115 Topic Category
Theme_Keyword: geoscientificInformation
Theme_Keyword: oceans
Theme:
Theme_Keyword_Thesaurus: USGS Thesaurus
Theme_Keyword: sub-bottom profiling
Theme_Keyword: marine geology
Theme_Keyword: geology
Theme_Keyword: coastal processes
Theme:
Theme_Keyword_Thesaurus: Data Categories for Marine Planning
Theme_Keyword: distributions
Theme_Keyword: physical habitats and geomorphology
Theme:
Theme_Keyword_Thesaurus: Marine Realms Information Bank (MRIB) Keywords
Theme_Keyword: seismic reflection profiling
Theme:
Theme_Keyword_Thesaurus: None
Theme_Keyword: Seismic reflection
Theme_Keyword: Chirp
Theme_Keyword: Society of Exploration Geophysicists
Theme_Keyword: SEG Y
Theme_Keyword: Barrier Island Mapping
Theme_Keyword: 2015-331-FA
Place:
Place_Keyword_Thesaurus: Geographic Names Information System (GNIS) Content
Place_Keyword: United States of America
Place_Keyword: Louisiana
Place_Keyword: Gulf of Mexico
Place_Keyword: Chandeleur Islands
Access_Constraints: None. These data are held in the public domain.
Use_Constraints:
Public domain data from the U.S. Government are freely redistributable with proper metadata and source attribution. The U.S. Geological Survey requests to be acknowledged as originator of the data in future products or derivative research.
Point_of_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Arnell S. Forde
Contact_Organization: U.S. Geological Survey
Contact_Position: Geologist
Contact_Address:
Address_Type: mailing and physical
Address: 600 4th Street South
City: Saint Petersburg
State_or_Province: FL
Postal_Code: 33701
Country: USA
Contact_Voice_Telephone: (727) 502-8000
Contact_Electronic_Mail_Address: aforde@usgs.gov
Data_Set_Credit:
Funding and (or) support for this study was provided by the USGS Coastal and Marine Geology Program. The authors thank Kyle Kelso of the USGS SPCMSC for his assistance in data collection and piloting the research vessel (R/V) Sallenger. This document was improved by reviews from Noreen Buster and and Xan Fredericks of the USGS - St. Petersburg, Florida.
Native_Data_Set_Environment:
Environment as of Metadata Creation: Microsoft Windows 7 Version 6.1 (Build 7601) Service Pack 1; Environmental Systems Research Institute (Esri) ArcGIS 10.3.1.4959
Cross_Reference:
Citation_Information:
Originator: Barry, K.M., Cavers, D.A., and Kneale, C.W.
Publication_Date: 1975
Title: Recommended standards for digital tape formats
Series_Information:
Series_Name: Geophysics
Issue_Identification: v. 40, no. 2
Other_Citation_Details: pages 344-352
Online_Linkage: http://www.seg.org/publications/tech-stand/
Cross_Reference:
Citation_Information:
Originator: Cohen, J.K., and Stockwell, J.W., Jr., CWP/SU
Publication_Date: 2010
Title:
Seismic Un*x Release No. 44: An open source software package for seismic research and processing
Publication_Information:
Publication_Place: Golden, Colorado
Publisher: Center for Wave Phenomena, Colorado School of Mines
Online_Linkage: http://www.cwp.mines.edu/cwpcodes/
Data_Quality_Information:
Attribute_Accuracy:
Attribute_Accuracy_Report:
The validity or accuracy of marine subbottom profiles is highly qualitative and dependent on equipment and operating condition variables. Visual inspection of the images rendered from the data did not show major anomalies.
Logical_Consistency_Report:
These datasets are from one field activity with consistent instrument calibrations.
Completeness_Report:
A total of 57 seismic lines were collected during this survey. These data are collected along 2D tracklines and are therefore inherently incomplete.
Positional_Accuracy:
Horizontal_Positional_Accuracy:
Horizontal_Positional_Accuracy_Report:
Differential global positioning system (DGPS) correction was obtained through the Marinestar high precision (HP) broadcast subscription from Fugro, Inc., which has a manufacturer's stated horizontal accuracy of 10 centimeters (cm). To ensure consistent spacing between survey lines (for example, 5 m in the nearshore and 10 m for offshore lines), pre-determined trackline locations were imported into Hypack 15.0.1.1 navigation software and followed during seismic data collection. As the subbottom data were acquired, vessel position was recorded in real-time kinematic mode via the CodaOctopus F190R+ Precision Attitude and Positioning System, which integrates the Marinestar position data with measured vessel heave, pitch, and roll. Positions from the CodaOctopus F190R+ inertial aided navigation system (IANS) were recorded and written to seismic trace headers in latitude and longitude coordinates (World Geodetic System of 1984, WGS84) every 1 second (s). The approximate 4-m offset between the chirp shot and ship's GPS was not accounted for during acquisition, nor have the ASCII navigation files and trackline map been corrected to reflect the offset.
Vertical_Positional_Accuracy:
Vertical_Positional_Accuracy_Report:
These data are not to be used for bathymetry. Two-way travel (TWT) times shown on the printable profile images are relative to the chirp towfish position, not to the sea surface.
Lineage:
Process_Step:
Process_Description:
Chirp processing: The SEG Y data were processed with Seismic Unix (Release 44) software to produce gained Graphics Interchange Format (GIF) images of the subbottom profiles included in this data release. A representative chirp data processing sequence consisted of (1) removing navigation data for each shot and converting the SEG Y file to SU format, (2) applying automatic gain control, (3) generating a PostScript image of the traces, and (4) converting the PostScript image to a GIF image. For additional SU processing and script details, please refer to Data Series 1077 (Forde and others, 2018).
Source_Used_Citation_Abbreviation: SEG Y
Process_Date: 2016
Source_Produced_Citation_Abbreviation: SEG Y.gif
Process_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Arnell S. Forde
Contact_Organization: U.S. Geological Survey
Contact_Position: Geologist
Contact_Address:
Address_Type: mailing and physical address
Address: 600 4th Street South
City: St. Petersburg
State_or_Province: FL
Postal_Code: 33701
Contact_Voice_Telephone: (727) 502-8000
Contact_Electronic_Mail_Address: aforde@usgs.gov
Process_Step:
Process_Description:
Navigation processing: Location data were extracted from the SEG Y headers using Seismic Unix software and output as ASCII text files; PROJ.4.7.0 (http://trac.osgeo.org/proj/) software was used to project WGS84 latitude and longitude coordinates to Universal Transverse Mercator (UTM) northings and eastings (WGS84, Zone 16, meters). Raw navigation files for each seismic line, saved by Julian Day (JD) and line number, were concatenated into comma-delimited text files for use with Esri ArcGIS software. The final output files are as follows: (1) 2015-331-FA.txt contains unique shotpoint positions (along each line) for the entire survey, (2) s2015-331-FA.txt includes the 1,000-shot-interval locations that were generated to correlate shot locations on the trackline map with evenly spaced 1,000-shot index markers along the top of the printable profile images, and (3) 2015-331-FA_s has the start-of-line locations for each trackline. The concatenated, comma-delimited text files were later imported into ArcGIS and saved as either a point or polyline file (in Esri's shapefile format) for use in the map document (.mxd) included in this archive.
Source_Used_Citation_Abbreviation: JD*.txt
Process_Date: 2016
Source_Produced_Citation_Abbreviation: 2015-331-FA.txt
Source_Produced_Citation_Abbreviation: s2015-331-FA.txt
Source_Produced_Citation_Abbreviation: 2015-331-FA_s.txt
Process_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Arnell S. Forde
Contact_Organization: U.S. Geological Survey
Contact_Position: Geologist
Contact_Address:
Address_Type: mailing and physical address
Address: 600 4th Street South
City: St. Petersburg
State_or_Province: FL
Postal_Code: 33701
Contact_Voice_Telephone: (727) 502-8000
Contact_Electronic_Mail_Address: aforde@usgs.gov
Process_Step:
Process_Description:
Trackline map creation: 2015-331-FA_location.mxd was created with Esri ArcGIS 10.3.1 software. The survey navigation file, 2015-331-FA.txt, was imported into ArcMap 10.3.1 and processed using the ArcScript "Points to Lines" to create a line shapefile of the cruise tracklines called 2015-331-FA_trkln. The 1,000-shot-interval file and the start-of-line file were imported into ArcMap and saved as point shapefiles 2015-331-FA_shots and 2015-331-FA_sol, respectively. The ArcGIS files included in this release are unprojected (geographic coordinates, WGS84). Please refer to the shapefile metadata and readme file, included in 2015-331-FA_arc.zip, for detailed information about the geospatial files provided in this data release.
Source_Used_Citation_Abbreviation: 2015-331-FA.txt
Source_Used_Citation_Abbreviation: s2015-331-FA.txt
Source_Used_Citation_Abbreviation: 2015-331-FA_s.txt
Process_Date: 2016
Source_Produced_Citation_Abbreviation: 2015-331-FA_trkln.shp
Source_Produced_Citation_Abbreviation: 2015-331-FA_shots.shp
Source_Produced_Citation_Abbreviation: 2015-331-FA_sol.shp
Process_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Arnell S. Forde
Contact_Organization: U.S. Geological Survey
Contact_Position: Geologist
Contact_Address:
Address_Type: mailing and physical address
Address: 600 4th Street South
City: St. Petersburg
State_or_Province: FL
Postal_Code: 33701
Contact_Voice_Telephone: (727) 502-8000
Contact_Electronic_Mail_Address: aforde@usgs.gov
Process_Step:
Process_Description:
Added keywords section with USGS persistent identifier as theme keyword.
Process_Date: 20201013
Process_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: U.S. Geological Survey
Contact_Person: VeeAnn A. Cross
Contact_Position: Marine Geologist
Contact_Address:
Address_Type: Mailing and Physical
Address: 384 Woods Hole Road
City: Woods Hole
State_or_Province: MA
Postal_Code: 02543-1598
Contact_Voice_Telephone: 508-548-8700 x2251
Contact_Facsimile_Telephone: 508-457-2310
Contact_Electronic_Mail_Address: vatnipp@usgs.gov
Spatial_Data_Organization_Information:
Direct_Spatial_Reference_Method: Point
Spatial_Reference_Information:
Horizontal_Coordinate_System_Definition:
Geographic:
Latitude_Resolution: 0.0197884765
Longitude_Resolution: 0.0227336944
Geographic_Coordinate_Units: Decimal Degrees
Geodetic_Model:
Horizontal_Datum_Name: World Geodetic System of 1984
Ellipsoid_Name: WGS 1984
Semi-major_Axis: 6378137.0
Denominator_of_Flattening_Ratio: 298.257223563
Entity_and_Attribute_Information:
Detailed_Description:
Entity_Type:
Entity_Type_Label: 2015-331-FA.txt, s2015-331-FA.txt, 2015-331-FA_s.txt
Entity_Type_Definition: Shotpoint navigation files
Entity_Type_Definition_Source: SEG Y headers http://www.seg.org/publications/tech-stand.
Attribute:
Attribute_Label: UTMX
Attribute_Definition: UTM-X coordinate (Zone 16)
Attribute_Definition_Source: Universal Transverse Mercator Coordinate System
Attribute_Domain_Values:
Range_Domain:
Range_Domain_Minimum: 319211.339
Range_Domain_Maximum: 323123.872
Attribute_Units_of_Measure: meters
Attribute:
Attribute_Label: UTMY
Attribute_Definition: UTM-Y coordinate (Zone 16)
Attribute_Definition_Source: Universal Transverse Mercator Coordinate System
Attribute_Domain_Values:
Range_Domain:
Range_Domain_Minimum: 3322594.357
Range_Domain_Maximum: 3328251.18
Attribute_Units_of_Measure: meters
Attribute:
Attribute_Label: Line
Attribute_Definition: Trackline number
Attribute_Definition_Source: U.S. Geological Survey
Attribute_Domain_Values:
Unrepresentable_Domain:
The naming convention used for each subbottom line is as follows: JD###_LxFy, where '###' is the integer assigned on the Julian Day (JD) of data collection, 'L' is an abbreviation of line and precedes the line number, 'x' is a 1- or 2-digit number representing a specific trackline number, 'F' is an abbreviation of file, and 'y' is a number representing a new line if recording was prematurely terminated or reran for quality or acquisition problems. If a trackline exceeded the file size limit/maximum shotpoint number (as determined by the acquisition software, Discover v. 3.51) the filename was appended with sequentially increasing numbers such as .001, .002, etc.
Attribute:
Attribute_Label: Shot
Attribute_Definition: Shotpoint number
Attribute_Definition_Source: U.S. Geological Survey
Attribute_Domain_Values:
Range_Domain:
Range_Domain_Minimum: 1
Range_Domain_Maximum: 16000
Attribute:
Attribute_Label: Lon
Attribute_Definition: Longitude (decimal degrees)
Attribute_Definition_Source: World Geodetic System 1984 Geographic Coordinate System
Attribute_Domain_Values:
Range_Domain:
Range_Domain_Minimum: -88.877667
Range_Domain_Maximum: -88.832981
Attribute_Units_of_Measure: decimal degrees
Attribute:
Attribute_Label: Lat
Attribute_Definition: Latitude (decimal degrees)
Attribute_Definition_Source: World Geodetic System 1984 Geographic Coordinate System
Attribute_Domain_Values:
Range_Domain:
Range_Domain_Minimum: 30.015653
Range_Domain_Maximum: 30.072044
Attribute_Units_of_Measure: decimal degrees
Attribute:
Attribute_Label: YEAR
Attribute_Definition: Year
Attribute_Definition_Source: U.S. Geological Survey
Attribute_Domain_Values:
Range_Domain:
Range_Domain_Minimum: 2015
Range_Domain_Maximum: 2015
Attribute:
Attribute_Label: DOY:HR:MIN:SEC
Attribute_Definition: Day of year:hour:minute:second
Attribute_Definition_Source: U.S. Geological Survey
Attribute_Domain_Values:
Unrepresentable_Domain: Day of year, hour, minute and second of data acquisition
Overview_Description:
Entity_and_Attribute_Overview:
Binary data file: Seismic trace data are available as binary files in SEG Y format. These files have a .sgy extension and range in size from 2.5 to 123 MB. These data are included in the download file, 2015-331-FA_segy.zip, and can also be found by going to http://cmgds.marine.usgs.gov. The SEG Y rev. 0 format (Barry and others, 1975) presented here consists of the following: a 3,600-byte reel identification header, with the first 3,200 bytes consisting of an ASCII header block followed by a 400-byte binary header block, both of which 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.
Entity_and_Attribute_Overview:
Graphic image file: Printable versions of the processed subbottom profiles are available as GIF images and are included in the download file, 2015-331-FA_seisimag.zip.
Entity_and_Attribute_Overview:
Navigation file: Navigation files are available as ASCII text files. Provided are raw shotpoint navigation files, reprojected survey shotpoint navigation, 1,000-shot-interval locations, and start of line files. The final navigation files are provided in 2015-331-FA_nav.zip.
Entity_and_Attribute_Overview:
GIS file: The GIS data associated with this survey are provided as a compressed zip file, 2015-331-FA_arc.zip, which is composed of an Esri map document, shapefiles, a folder for the processed profile images, shapefile metadata and a readme file. The shapefiles provided may also be viewed using other versions of Esri desktop software including their free software Explorer for ArcGIS, which is available at http://www.esri.com/software/arcgis/explorer/index.html.
Entity_and_Attribute_Detail_Citation:
The entity and attribute information was generated by the individual and/or agency identified as the originator of the dataset. Please review the rest of the metadata record for additional details and information.
Distribution_Information:
Distributor:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Arnell S. Forde
Contact_Organization: U.S. Geological Survey
Contact_Position: Geologist
Contact_Address:
Address_Type: mailing and physical
Address: 600 4th Street South
City: St. Petersburg
State_or_Province: FL
Postal_Code: 33701
Country: USA
Contact_Voice_Telephone: (727) 502-8000
Contact_Electronic_Mail_Address: aforde@usgs.gov
Contact_Instructions:
All of this publication is available online. The SEG Y files are also downloadable from the Coastal and Marine Geoscience Data System https://cmgds.marine.usgs.gov.
Distribution_Liability:
This publication was prepared by an agency of the United States Government. Although these data were processed successfully on a computer system at the U.S. Geological Survey, no warranty expressed or implied is made regarding the display or utility of the data on any other system, nor shall the act of distribution imply any such warranty. The U.S. Geological Survey shall not be held liable for improper or incorrect use of the data described and (or) contained herein. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof.
Standard_Order_Process:
Digital_Form:
Digital_Transfer_Information:
Format_Name: SEG Y
Format_Version_Number: Revision 0
File_Decompression_Technique: Winzip or 7zip
Transfer_Size: 6730
Digital_Transfer_Option:
Online_Option:
Computer_Contact_Information:
Digital_Form:
Digital_Transfer_Information:
Format_Name: ASCII
File_Decompression_Technique: Winzip or 7zip
Transfer_Size: 4.40
Digital_Transfer_Option:
Online_Option:
Computer_Contact_Information:
Digital_Form:
Digital_Transfer_Information:
Format_Name: SHP (Esri shapefile)
File_Decompression_Technique: Winzip or 7zip
Transfer_Size: 1.70
Digital_Transfer_Option:
Online_Option:
Computer_Contact_Information:
Digital_Form:
Digital_Transfer_Information:
Format_Name: GIF
File_Decompression_Technique: Winzip or 7zip
Transfer_Size: 48.6
Digital_Transfer_Option:
Online_Option:
Computer_Contact_Information:
Fees: None
Technical_Prerequisites:
Use of SEG Y data requires specialized seismic processing software, such as public domain software Seismic Unix http://www.cwp.mines.edu/cwpcodes/index.html.
Metadata_Reference_Information:
Metadata_Date: 20201013
Metadata_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Arnell S. Forde
Contact_Organization: U.S. Geological Survey
Contact_Position: Geologist
Contact_Address:
Address_Type: mailing and physical
Address: 600 4th Street South
City: St. Petersburg
State_or_Province: FL
Postal_Code: 33701
Country: USA
Contact_Voice_Telephone: (727) 502-8000
Contact_Electronic_Mail_Address: aforde@usgs.gov
Metadata_Standard_Name: Content Standard for Digital Geospatial Metadata
Metadata_Standard_Version: FGDC-STD-001-1998

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