Seismic Reflection Results from the Gyre 1997 Cruise at the Bryant Canyon of the Louisiana Gulf Coast

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Frequently anticipated questions:


What does this data set describe?

Title:
Seismic Reflection Results from the Gyre 1997 Cruise at the Bryant Canyon of the Louisiana Gulf Coast
Abstract:
This CD-ROM contains digital high resolution seismic-reflection data collected during the USGS GYRE 97006 cruise. The coverage is the offshore Louisana continental slope, Gulf of Mexico. The seismic-reflection data are stored as IBM 4 bit interger SEG-Y format that can be read and manipulated by most seismic-processing software. Much of the information specific to the data are contained in the headers of the SEG-Y format files. The file system format is ISO 9660 which can be read with DOS, Unix, and MAC operating systems with the appropriate CD-ROM driver software installed. This directory contains the processed (using Promax 7.2) and unprossesd (RAW) GI air gun data collected on the GYRE 97006 cruise. These data were collected using a Seismic Systems Inc. generated injected (GI) air gun source. On this cruise the GI gun was configured with two 105 cu. in. chambers, a total of 210 cu. in. The GI gun works by using one chamber for a primary pulse and the second chamber injects a pulse near the maximum expansion of the primary pulse. This results in a dampening effect on the collapse of the primary bubble pulse. The data were logged on an Intel based PC computer (Mudseis system). The data are two-channel (two traces per shot).
Supplemental_Information:
The publication contains both the raw and processed SEG-Y files, as well as navigation and JPEG images of the profiles. These data were acquired on U.S. Geological Survey field activity 1997-006-FA. More information is available from: https://cmgds.marine.usgs.gov/fan_info.php?fan=1997-006-FA.
  1. How might this data set be cited?
    Nealon, Jeffrey, 1999, Seismic Reflection Results from the Gyre 1997 Cruise at the Bryant Canyon of the Louisiana Gulf Coast: Open-File Report 99-449, U.S. Geological Survey, Woods Hole, MA.

    Online Links:

    This is part of the following larger work.

    Nealon, Jeffrey W., Dillon, William P., and Twichell, David, 2000, Seismic reflection results from the GYRE 1997 cruise of the Bryant Canyon on the Louisiana Gulf Coast: Open-File Report 99-449, U.S. Geological Survey, Reston, VA.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -92.833333
    East_Bounding_Coordinate: -91.916667
    North_Bounding_Coordinate: 27.5
    South_Bounding_Coordinate: 26.25
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 09-Apr-1997
    Beginning_Time: 045227
    Ending_Date: 13-Apr-1997
    Ending_Time: 131459
    Currentness_Reference:
    not available from original metadata - assumed to be the start and end of the data acquisition
  5. What is the general form of this data set?
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      Indirect_Spatial_Reference: Gulf of Mexico, Louisiana Continental Slope
    2. What coordinate system is used to represent geographic features?
      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:
      UTM_Zone_Number: 15
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: .9997
      Longitude_of_Central_Meridian: -93
      Latitude_of_Projection_Origin: 0
      False_Easting: 0
      False_Northing: 0
      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest 5
      Ordinates (y-coordinates) are specified to the nearest 5
      Planar coordinates are specified in meters
      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.
      The flattening of the ellipsoid used is 1/298257.
      Vertical_Coordinate_System_Definition:
      Altitude_System_Definition:
      Altitude_Datum_Name: assumed sea level
      Altitude_Resolution: 1
      Altitude_Distance_Units: two-way travel time
      Altitude_Encoding_Method: Attribute values
      Depth_System_Definition:
      Depth_Datum_Name: fish depth below sea level (local surface)
      Depth_Resolution: 1
      Depth_Distance_Units: meters
      Depth_Encoding_Method: Attribute values
  7. How does the data set describe geographic features?
    Entity_and_Attribute_Overview:
    Direct_spatial_Reference_method: raster Raster_Object Information: Raster_Object_Type: Voxel Row_Count: > 10000 Column_Count: 1 Vertical Count: 4096
    Entity_and_Attribute_Detail_Citation:
    Based on the direct spatial reference method in the original metadata that didn't meet the standard formatting requirements.

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Nealon, Jeffrey
  2. Who also contributed to the data set?
    D. Twichell, D. Nichols, T. O'Brien, B. Irwin, V. Cross, M. Taylor D. Foster, B. Danforth, S. Harrison, J. Brand, C. Spagnuolo
  3. To whom should users address questions about the data?
    Twichell, Dave
    U.S. Geological Survey
    Seafloor Mapping Project
    U.S. Geological Survey
    Woods Hole Field Center
    384 Woods Hole Road
    Quissett Campus
    Woods Hole, MA
    USA

    (508) 548-8700 (voice)
    (508) 457-2310 (FAX)
    dtwichell@usgs.gov

Why was the data set created?

The seismic-reflection data are being archived so that further digital processing can be done for the seafloor mapping project: TECTONICS AND SEDIMENTARY PROCESSES OF THE SALT DEFORMED TEXAS-LOUISIANA CONTINENTAL SLOPE. This project proposes (1) mapping the surficial geology of a large part of the TX-LA slope using advanced processing techniques and existing GLORIA and multibeam data, (2) conducting a higher resolution sidescan and sampling cruise to refine the understanding of tectonic, sediment supply, and oceanographic controls on sedimentary processes, (3) linking the surficial geology with the subsurface structures and stratigraphy for modern and ancient comparison of sedimentary systems, and (4) integrating data into a three-dimensional model of depositional systems in this complex environment.

How was the data set created?

  1. From what previous works were the data drawn?
  2. How were the data generated, processed, and modified?
    Date: unknown (process 1 of 3)
    The original SEG-Y files were acquired from David C. Twichell on CD-ROM.
    Flow 1 : load file and geometry
    2D Marine geometry spreadsheet
    Seg-Y Input
    File to input: Raw.seg-y
    Store Processing History:Yes
    Input Auxiliary Traces: Yes
    Get Channel Number from Trace Headers: Yes
    Input Trace Format: Get from Headers
    Display ensemble Formation: No
    Data Input Sample Rate: 0.5 msec
    Maximum Time to input: variable
    Is this Stacked Data: No
    Max Traces Per Ensemble: 120
    Primary Sort Header Word: SHOT
    Input Primary Selection Choice:Input all
    Input secondary selection Choice:None
    Input global XY coordinates: No
    Use coordinate Scalar: Yes
    Remap Seg-Y header Values: No
    Inline Geometry header Load
    water velocity: 1525
    Primary header to match database: FFID
    Secondary Header to match database: None
    Match by Valid trace Number: NO
    Drop traces with Null CDP headers: No
    Drop Traces with Null receiver Headers: No
    Verbose Diagnostics: YES
    Trace header Math
    select Mode:fixed equation Mode
    define header equation:FFID =CDP
    Disk Data Output
    output dataset file Name: geom
    New or existing file:New
    record length to output:0(default parameter means include all)
    Trace sample format:16 bit
    Skip primary disk storage:No
    Flow 2: Mute and Deconvolution
    Disk Data Input
    Read data from other lines/surveys:No
    Select input file: geom
    Trace read option: Get all
    Read data multiple times: No
    Input trace headers only: No
    Override input datas sample interval:No
    Trace Muting
    Reapply Previous mutes: no
    Mute time reference:Time 0
    Type of Mute: TOP
    Starting ramp:30
    Extrapolate mute times:No
    Get Mute Times from Database:Yes
    Select Database:Topmute(Horizon picked ~300 ms above seafloor)
    True Amplitude recovery
    Apply spherical divergence corrections: NO
    Apply inelastic attenuation correction: NO
    Apply db/sec corrections:YES
    DB per second constant:6
    Apply time raise to a power corrections:NO
    Time power constant:NO
    Apply effect to data or remove function:APPLY
    Maximum application Time: 3500-4000
    Spiking Predictive decon
    Type of deconvolution:MIN PHASE SPIKING
    Decon Operator length:80
    Operator white noise level:.1
    window rejection length:2
    Time gate reference:DATABASE FILE
    Select decon gate from Database: Yes Select database:DECON
    Output traces or filters:TRACES
    Apply a band pass filter after decon:NO
    Reapply mutes after decon:YES
    Disk Data Output
    Output dataset file Name:decon
    New or existing file:New
    record length to output:0(default parameter means include all)
    Trace sample format:16 bit
    Skip primary disk storage:No
    Flow 3 Stack
    Disk Data Input
    Read data from other lines/surveys: No
    Select input file:decon
    Trace read option:sort
    Primary Sort header word:CDP
    Secondary sort header word:NONE
    Sort order dataset:*/
    Presort in memory or disk:Memory
    Read data multiple times:No
    Input trace headers only: No
    Override input datas sample interval:No
    CDP Ensemble Stack
    sort order of input ensembles:CDP
    Method of trace summing:Mean
    root Power scalar for stack normalization:0.5
    Apply final datum statics after Stack:Yes
    Has NMO been applied:No
    Disk Data Output
    Output dataset file Name:stack
    New or existing file:New
    record length to output:0(default parameter means include all)
    Trace sample format:16 bit
    Skip primary disk storage:No
    Disk Data Input
    Read data from other lines/surveys:No
    Select input file:stack
    Trace read option:get all
    Read data multiple times:No
    Input trace headers only:No
    Override input data's sample interval:No
    Bandpass Filter
    Type of Filter:single filter
    Type of filter specification:ormsby bandpass
    Phase of filter:Zero
    domain of filter application:Frequency
    Percent zero padding for FFT:25
    Apply notch filter:no
    Ormbsby bandpass filter values:4-8-100-150
    Reapply trace mute after filter:yes
    Seg-Y Output
    type of seg-y:standard
    file name:line1pro.sgy
    Retrieve history form header:yes
    copy reel header:default
    job id for binary header:9999
    line number for binary header:9999
    desired trace format:4 bit integer
    maximum time to output:variable
    remap seg-y header values:no
    Date: 19-Jan-2022 (process 2 of 3)
    Add the larger work citation to incorporate all the authors. Fixed errors flagged by MP, which results in "information not available from original metadata" in some instances. Added the field activity to the supplemental information. Added USGS Thesaurus and ISO 19115 Topic Category theme keywords. Removed the source citation information - and moved the brief information to the first process step. Removed empty, non-required fields. Updated the distribution information. Modified the distribution information to include the data formats and links to the data. The metadata date (19970408), but not the contact (except email and contact instructions) was updated. The metadata available from a harvester may supersede metadata available from the publication. Compare the metadata dates to determine which metadata file is most recent. Person who carried out this activity:
    U.S. Geological Survey
    Attn: VeeAnn A. Cross
    Marine Geologist
    384 Woods Hole Road
    Woods Hole, MA

    508-548-8700 x2251 (voice)
    508-457-2310 (FAX)
    vatnipp@usgs.gov
    Date: 06-Aug-2024 (process 3 of 3)
    Added keywords section with USGS persistent identifier as theme keyword. Person who carried out this activity:
    U.S. Geological Survey
    Attn: VeeAnn A. Cross
    Marine Geologist
    384 Woods Hole Road
    Woods Hole, MA

    508-548-8700 x2251 (voice)
    508-457-2310 (FAX)
    vatnipp@usgs.gov
  3. What similar or related data should the user be aware of?

How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?
  2. How accurate are the geographic locations?
    The ship was navigated with differential GPS The GI air gun was towed 10 m aft of the ship The two-channel streamer was towed 100 m aft of the ship. Each channel consisted of a 25 m length of streamer. accurate within 5-10 meters
  3. How accurate are the heights or depths?
    The air gun was towed at depth of 1 meter. The streamer was towed at a depth of 5 meters. Vertical resolution of the seismic data is about 1-2 meters. There was no correction to a datum such as mean sea level.
  4. Where are the gaps in the data? What is missing?
    archive of SEG-Y format seismic data
  5. How consistent are the relationships among the observations, including topology?
    information not available from original metadata

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?
Access_Constraints none
Use_Constraints none
  1. Who distributes the data set? (Distributor 1 of 1)
    Soderberg, Nancy
    U.S. Geological Survey
    Data Library
    U.S. Geological Survey
    Woods Hole Field Center
    384 Woods Hole Road
    Quissett Campus
    Woods Hole, MA
    USA

    (508) 548-8700 (voice)
    (508) 457-2310 (FAX)
    nsoderberg@usgs.gov
  2. What's the catalog number I need to order this data set? U.S. Geological Suvey Internal CD-ROM Data Archive
  3. What legal disclaimers am I supposed to read?
    Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty.
  4. How can I download or order the data?

Who wrote the metadata?

Dates:
Last modified: 06-Aug-2024
Metadata author:
Foster, David
U.S. Geological Survey
Geophysics Group
U.S. Geological Survey
Woods Hole Field Center
384 Woods Hole Road
Quissett Campus
Woods Hole, MA
USA

(508) 548-8700 (voice)
(508) 457-2310 (FAX)
whsc_data_contact@usgs.gov
Contact_Instructions:
The metadata contact email address is a generic address in the event the metadata contact is no longer with the USGS.
Metadata standard:
FGDC Content Standard (FGDC-STD-001-1998)

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