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- Identification_Information:
-
- Citation:
-
- Citation_Information:
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- Originator: Patrick E. Hart
- Originator: Deborah R. Hutchinson
- Originator: Myung Lee
- Publication_Date: 2005
- Title:
-
High-resolution multichannel seismic-reflection data
acquired in the northern Gulf of Mexico, 2003
- Series_Information:
-
- Series_Name: U.S. Geological Survey Open-File Report
- Issue_Identification: 05-1411
- Publication_Information:
-
- Publication_Place: Menlo Park, CA
- Publisher: U.S. Geological Survey
- Online_Linkage: <http://geopubs.wr.usgs.gov/open-file/of05-1411/>
- Geospatial_Data_Presentation_Form: seismic reflection profile section
- Description:
-
- Abstract:
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This report consists of two-dimensional marine seismic
reflection profile data from the northern Gulf of Mexico. These data
were acquired in 2003 with the Research Vessel Gyre (G-1-03-GM). The
data are available in binary and JPEG image formats. Binary data are
in Society of Exploration Geologists (SEG) SEG-Y format and may be
downloaded for further processing or display. Reference maps and
JPEG images of the profiles may be viewed with your Web browser.
- Purpose:
-
Marine seismic reflection data are used to image and map
sedimentary and structural features of the seafloor and subsurface.
These data were acquired across the upper and middle continental
slope of the northern Gulf of Mexico as part of an investigation of
the of the seismic character, distribution, and potential effects of
naturally-occurring marine gas hydrates and related free gas within
the gas hydrate stability zone. The specific objectives of this
investigation are: (a) To provide site survey information for the
two JIP drilling sites/lease blocks (Keathley Canyon 195 and Atwater
Valley 14). (b) To tie the new data to regional coverages in the
Gulf. (c) To tie the Marion Dufresne coring sites into the regional
MCS grid. (d) To provide baseline information for selecting targets
for the August 2003 NRL/DOE Gyre cruise. The seismic profiles provide
high-quality images with approximately 5 meters of vertical
resolution and up to 2 km of subbottom penetration.
- Supplemental_Information:
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Multichannel seismic reflection profiles are
acquired by means of an acoustic source (usually compressed air
discharged via an air gun or water gun), and a hydrophone array.
Both elements are typically towed in the water behind a survey
vessel. The sound source emits a short acoustic pulse, which
propagates through the water and sediment columns. The acoustic
energy is reflected at acoustic impedance (the product of sound-speed
and density) boundaries (such as the seafloor or
sediment layers beneath the seafloor), and detected at the
hydrophone. As the vessel moves, this process is repeated at
intervals ranging between 10 and 30 meters depending on the source
type. In this way a two-dimensional image of the geologic structure
beneath the ship track is constructed.
Additional information about the USGS survey G-1-03-GM is
available at <http://pubs.usgs.gov/of/2003/of03-474/>.
The data window for G-1-03-GM is
-94.818 26.715 -89.239 29.345 (decimal degrees).
- Time_Period_of_Content:
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- Time_Period_Information:
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- Range_of_Dates/Times:
-
- Beginning_Date: 20030429
- Ending_Date: 20030516
- Currentness_Reference:
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Data assumed to be constant over time, but may
change due to geologic processes.
- Status:
-
- Progress: Complete
- Maintenance_and_Update_Frequency: None planned
- Spatial_Domain:
-
- Bounding_Coordinates:
-
- West_Bounding_Coordinate: -94.82
- East_Bounding_Coordinate: -89.24
- North_Bounding_Coordinate: +29.35
- South_Bounding_Coordinate: +26.72
- Keywords:
-
- Theme:
-
- Theme_Keyword_Thesaurus: none
- Theme_Keyword: U.S. Geological Survey
- Theme_Keyword: USGS
- Theme_Keyword: Coastal and Marine Geology Program
- Theme_Keyword: CMGP
- Theme:
-
- Theme_Keyword_Thesaurus:
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ISO 19115 Topic Category <http://gcmd.gsfc.nasa.gov/User/difguide/iso_topics.html>
- Theme_Keyword: geoscientific
- Theme_Keyword: imageryBaseMapsEarthCover
- Theme_Keyword: oceans
- Theme:
-
- Theme_Keyword_Thesaurus:
-
Olsen, L.M., G. Major, S. Leicester, K. Shein, J. Scialdone,
H. Weir, S. Ritz, C. Solomon, M. Holland, R. Bilodeau,
T. Northcutt, R. Vogel.
2004.
NASA/Global Change Master Directory (GCMD) Earth Science Keywords.
Version 5.1.1
[online: <http://gcmd.nasa.gov/Resources/valids/keyword_list.html>]
- Theme_Keyword: Gas Hydrates
- Theme_Keyword: AIRGUN ARRAYS
- Theme_Keyword: WATERGUNS
- Theme_Keyword: MULTICHANNEL FILTER RADIOMETERS
- Theme_Keyword: SEISMIC REFLECTION PROFILERS
- Theme:
-
- Theme_Keyword_Thesaurus: none
- Theme_Keyword: marine seismic reflection
- Theme_Keyword: gas hydrate
- Theme_Keyword: air gun
- Theme_Keyword: water gun
- Theme_Keyword: multichannel
- Theme_Keyword: SEG-Y
- Theme_Keyword: G-1-03-GM
- Theme_Keyword: G1-03-GM
- Place:
-
- Place_Keyword_Thesaurus:
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Geographic Names Information System (GNIS)
<http://geonames.usgs.gov/>
- Place_Keyword: Gulf of Mexico
- Place:
-
- Place_Keyword_Thesaurus: none
- Place_Keyword: Northern Gulf of Mexico
- Place_Keyword: Mississippi Canyon
- Place_Keyword: Keathley Canyon
- Place_Keyword: Atwater Valley
- 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: Patrick E. Hart
- Contact_Organization: U.S. Geological Survey
- Contact_Position: geophysicist
- Contact_Address:
-
- Address_Type: mailing address
- Address: USGS, MailStop 999, 345 Middlefield Road
- City: Menlo Park
- State_or_Province: CA
- Postal_Code: 94025-3561
- Country: USA
- Contact_Voice_Telephone: (650) 329-5160
- Contact_Electronic_Mail_Address: hart@usgs.gov
- Browse_Graphic:
-
- Browse_Graphic_File_Name:
-
<http://pubs.usgs.gov/of/2005/1411/images/gom_index.gif>
- Browse_Graphic_File_Description:
-
Map of Northern Gulf of Mexico showing areas of 2003 USGS seismic
research cruise
- Browse_Graphic_File_Type: JPEG
- Cross_Reference:
-
- Citation_Information:
-
- Originator: Deborah R. Hutchinson
- Originator: Patrick E. Hart
- Publication_Date: 2003
- Title:
-
Cruise Report for G1-03-GM, USGS Gas Hydrates Cruise,
R/V Gyre, 1-14 May 2003, Northern Gulf of Mexico
- Series_Information:
-
- Series_Name: USGS Open-File Report
- Issue_Identification: 03-474
- Publication_Information:
-
- Publication_Place: Woods Hole, MA
- Publisher: U. S. Geological SurveyCross_Reference
- Other_Citation_Details: <http://pubs.usgs.gov/of/2003/of03-474/>
- Cross_Reference:
-
- Citation_Information:
-
- Originator: Patrick E. Hart
- Originator: Alan K. Cooper
- Originator: David Twichell
- Originator: Myung Lee
- Originator: Warren Agena
- Publication_Date: 2002
- Title:
-
High-Resolution Multichannel Seismic-Reflection Data Acquired
in the Northern Gulf of Mexico, 1998-99
- Series_Information:
-
- Series_Name: USGS Open-File Report
- Issue_Identification: 02-368
- Publication_Information:
-
- Publication_Place: Menlo Park, CA
- Publisher: U. S. Geological Survey
- Other_Citation_Details: <http://geopubs.wr.usgs.gov/open-file/of02-368/>
- Cross_Reference:
-
- Citation_Information:
-
- Originator: Myung Lee
- Originator: Patrick E. Hart
- Originator: Warren Agena
- Publication_Date: 2000
- Title:
-
Processing Strategy for Water-Gun Seismic Data from the Gulf
of Mexico
- Series_Information:
-
- Series_Name: USGS Bulletin
- Issue_Identification: 2181
- Publication_Information:
-
- Publication_Place: Denver, CO
- Publisher: U. S. Geological Survey
- Other_Citation_Details: <http://greenwood.cr.usgs.gov/pub/bulletins/b2181/>
- Cross_Reference:
-
- Citation_Information:
-
- Originator:
-
United States Geological Survey (USGS), Coastal and
Marine Geology (CMG)
- Publication_Date: 2005
- Title:
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USGS Coastal & Marine Geology InfoBank,
USGS CMG G-1-03-GM Metadata
- Online_Linkage:
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<http://walrus.wr.usgs.gov/infobank/g/g103gm/html/g-1-03-gm.meta.html>
- 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-Y format. A SEG-Y file consists of 1) a 3200-byte file
identification record of EBCDIC encoded 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, one
seismic reflection trace per record. 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 pressure recorded
at each hydrophone. The SEG-Y file is useful only if you have access
to specialized software designed to process and display seismic
reflection data.
- 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 JPEG image.
- 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 too numerous to quantify. There
have been no efforts to assess the validity of the data.
- Logical_Consistency_Report:
-
These data have not been assessed for
internal consistency.
- Completeness_Report:
-
These are sparse line coverages (2D).
Therefore, data are inherently incomplete. Geologic details between
lines must be inferred. The surveys were not designed to cover a
particular geographic area; the line spacings and azimuths were chosen
to assess geologic features related to known and inferred gas hydrate
deposits.
- Positional_Accuracy:
-
- Horizontal_Positional_Accuracy:
-
- Horizontal_Positional_Accuracy_Report:
-
Positions were determined with
differential Global Positioning System (GPS). Absolute position
accuracy was approximately plus/minus 10 m.
- Vertical_Positional_Accuracy:
-
- Vertical_Positional_Accuracy_Report:
-
The vertical position was local
sea level and there have been no corrections to a datum or for
tidal variations.
- Lineage:
-
- Process_Step:
-
- Process_Description:
-
2003 multichannel seismic data acquisition:
Acquisition and recording of air-gun and water-gun seismic
reflection data. The source consisted of either a 13/13 cubic inch
dual-chamber GI ("Generator-Injector") air gun, a 24/24 cubic inch
GI air gun, or a 15 cubic inch water gun. The "injector" chamber
of the GI gun was timed to discharge a short time (typically
20-30 msec) after the "generator" chamber so as to suppress the
bubble pulse and create an optimal signal. The streamer was
240 meters in length with a 10-meter group interval (three
hydrophones per group), and was manufactured by Innovative
Transducers, Inc. (ITI) with solid-core construction and
"thin-film" cylindrical hydrophones of polyvinylidene fluoride
(PVDF) plastic. A problem with a streamer connection caused the
far 2 channels to be very noisy, and these channels were eliminated
during data processing. Data were digitized with the Geometrics
Strataview seismograph and recorded with the Geometrics Marine
Controller in SEG-D format.
- Process_Date: 2003
- Process_Step:
-
- Process_Description:
-
Multichannel data processing: A representative
data processing sequence consisted of: 1. SEG-D input and
resample to 1.0 millisecond; 2. Geometry assignment and sort to
CDP at 5 m spacing; 3. Wavelet deconvolution (Derived wavelet
using 3 shot gathers and 16-18 msec window); 4. Predictive
deconvolution (1st-zero crossing, operator length = 60 msec and a
single design window); 5. Trace edit ; 6. Single window balance;
7. Band-pass filtering; 8. Common-Offset DMO; 9. Velocity
analysis and NMO; 10. Stack (12-fold where 10 m shot spacing,
6-fold where 20 m shot spacing, 4-fold where 30-m shot spacing);
11. True amplitude gain application on stacked data;
12. Post-stack 2nd-zero crossing deconvolution (Operator length =
30 msec and single design window); 13. Migration velocity analysis
based on the stacking velocity: Iteratively adjusted;
14. Migration; 15. Post-stack 40-400 Hz band-pass filtering ;
16. Water-bottom mute.
- Process_Date: 2003
- Process_Step:
-
- Process_Description:
-
Positional (navigation) data: As the seismic
reflection data were acquired, the position of the vessel was
continuously determined with the differnetial Global Positioning
System (GPS). GPS positions were recorded approximately every
second, and written to an ASCII file. This file was subsequently
used to determine the position of each seismic reflection
"shotpoint".
- Process_Date: 2003
- Process_Step:
-
- Process_Description:
-
Open File preparation The migrated seismic
profiles were converted from SEG-Y format to CGM plot files using
Paradigm Focus software. Then the CGM files were converted to
300 dots per inch JPEG image file using Larson CGM to Image
software.
- Process_Date: 2004
- Process_Contact:
-
- Contact_Information:
-
- Contact_Person_Primary:
-
- Contact_Person: Patrick E. Hart
- Contact_Organization: U.S. Geological Survey
- Contact_Position: geophysicist
- Contact_Address:
-
- Address_Type: mailing address
- Address: USGS, MailStop 999, 345 Middlefield Road
- City: Menlo Park
- State_or_Province: CA
- Postal_Code: 94025-3561
- Country: USA
- Contact_Voice_Telephone: (650) 329-5160
- Contact_Electronic_Mail_Address: hart@usgs.gov
- Spatial_Data_Organization_Information:
-
- Indirect_Spatial_Reference:
-
Horizontal X and Y locations for each shot
location are provided in ASCII position files.
- Spatial_Reference_Information:
-
- Horizontal_Coordinate_System_Definition:
-
- Geographic:
-
- Latitude_Resolution: 0.00001
- Longitude_Resolution: 0.00001
- Geographic_Coordinate_Units: decimal degrees
- Geodetic_Model:
-
- Horizontal_Datum_Name: WGS 84
- Ellipsoid_Name: WGS 84
- Semi-major_Axis: 6378137 m
- Denominator_of_Flattening_Ratio: 298.257
- Distribution_Information:
-
- Distributor:
-
- Contact_Information:
-
- Contact_Person_Primary:
-
- Contact_Person: Patrick E. Hart
- Contact_Organization: U.S. Geological Survey
- Contact_Position: geophysicist
- Contact_Address:
-
- Address_Type: mailing address
- Address: USGS, MailStop 999, 345 Middlefield Road
- City: Menlo Park
- State_or_Province: CA
- Postal_Code: 94025-3561
- Country: USA
- Contact_Voice_Telephone: (650) 329-5160
- Contact_Electronic_Mail_Address: hart@usgs.gov
- Contact_Instructions:
-
Data may be available off-line only by special
arrangement with the distributor above. Please use the on-line
download option unless precluded by download times or access
difficulties.
- Resource_Description: U.S. Geological Suvey Open-File Report 05-1411
- Distribution_Liability:
-
This dataset 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
information, apparatus, products, or processes disclosed in this
report, nor represents that its use would not infringe privately owned
rights. 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.
Although all data published in this report 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. The act of distribution
shall not constitute any such warranty, and no responsibility is
assumed by the USGS in the use of this data.
- Standard_Order_Process:
-
- Digital_Form:
-
- Digital_Transfer_Information:
-
- Format_Name: SEG-Y, JPEG, ASCII
- Transfer_Size: 8 gigabytes
- Digital_Transfer_Option:
-
- Online_Option:
-
- Computer_Contact_Information:
-
- Network_Address:
-
- Network_Resource_Name: <http://geopubs.wr.usgs.gov/open-file/of05-1411/>
- Offline_Option:
-
- Recording_Format: ISO 9660
- Offline_Media: CD-R or DVD-R
- Fees: none
- Technical_Prerequisites:
-
Use of SEG-Y data requires specialized software,
such as ProMax and Seisworks by Landmark Geophysical; FOCUS and SeisX
by Paradigm Geophysical; SPW by Parallel Geoscience; or VISTA by
Seismic Image Software.
- Metadata_Reference_Information:
-
- Metadata_Date: 20050822
- Metadata_Contact:
-
- Contact_Information:
-
- Contact_Person_Primary:
-
- Contact_Person: Patrick E. Hart
- Contact_Organization: U.S. Geological Survey
- Contact_Position: geophysicist
- Contact_Address:
-
- Address_Type: mailing address
- Address: USGS, MailStop 999, 345 Middlefield Road
- City: Menlo Park
- State_or_Province: CA
- Postal_Code: 94025-3561
- Country: USA
- Contact_Voice_Telephone: (650) 329-5160
- Contact_Electronic_Mail_Address: hart@usgs.gov
- Metadata_Standard_Name: Content Standard for Digital Geospatial Metadata
- Metadata_Standard_Version: FGDC-STD-001-1998
Generated by mp version 2.8.11 on Thu Aug 18 13:06:28 2005
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