OFFSHORE U.S. NON-EXCLUSIVE
GRAVITY & MAGNETIC INFORMATION

Blake Plateau - North Marine Gravity / Magnetic / Seismic Survey

Data

• Survey Size: 4,112 line miles
• Data Spacing: Variable
• Data Provided:
  Profiles showing: free-air gravity, 2-D Bouguer gravity, adjusted 2-D Bouguer gravity, water depth, total magnetic intensity minus Earth's normal field, adjusted total magnetic intensity minus Earth's normal field, intersection statistics
  Contour maps of: Bouguer gravity, magnetic anomalies, bathymetry
• Total Cost: $20,000
• Conditions of Sale: Seismic data available

Interpretation

• Available upon request

· Blake Plateau, North Map: 33K jpeg file

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Blake Plateau - South Marine Gravity / Magnetic / Seismic Survey

Data

• Survey Size: 4,200 line miles
• Data Spacing: Variable
• Data Provided:
  Profiles (1" = 5,280') at seismic scale showing: free-air gravity, adjusted free-air gravity, Bouguer gravity, water depth, total magnetic intensity minus Earth's normal field, adjusted total magnetic intensity minus Earth's normal field, line intersection statistics
  Bouguer Gravity Map (1/250,000)
  Total Magnetic Intensity Minus Earth's Normal Field Map (1/250,000)
  Bathymetry Map (1/250,000)
• Total Cost: $40,000
• Conditions of Sale: Seismic data available

Interpretation

• Available upon request

· Blake Plateau, South Map: 27K jpeg file

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Georgia Embayment Marine Gravity / Magnetic / Seismic Survey

Data

• Survey Size: 4,980 line miles
• Data Spacing: 1½ mile primary grid
• Data Provided:
  Profiles showing: free-air gravity, Bouguer gravity, final adjusted Bouguer gravity, Eötvös correction, total magnetic intensity, bathymetry
  Contour maps of: Bouguer gravity, magnetic anomalies, bathymetry
• Cost/Mile:
  $9.50/line mile if seismic is purchased
  $19.00/line mile if seismic is not purchased
• Conditions of Sale: Seismic data available

Integrated Gravity / Magnetic / Seismic / Geologic Structural Interpretation

• Data Provided:
  Magnetics Reduced-to-Pole Map
  Second Vertical Derivative of Magnetics Reduced-to-Pole Map
  Residual Gravity Map
  Composite Map showing basement depth, susceptibility blocks, trends, and faults
  Profiles illustrating basement depth, susceptibility blocks, trends, and faults
• Interpretation Cost: $15,000
• Conditions of Sale: Purchase of seismic data prerequisite for purchase of interpretation

· Georgia Embayment Map: 44K jpeg file

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Isostatic Anomaly Survey, Gulf of Mexico

Data

• Survey Size: 100,000 square miles
• Date: 1987
• Data set includes:
  Schafer underwater gravity
  Teledyne underwater gravity
  Petty-Ray shipborne gravity
  Tidelands shipborne gravity
  EDCON shipborne gravity
• Project Summary:
  An isostatic model for the crust of the Gulf of Mexico has been constructed. The calculated gravity effect of this crustal model represents a regional gravity effect which has been subtracted from the observed free-air gravity field resulting in an Isostatic Anomaly Map.
  Ownership of the underlying basic data sets is a prerequisite to purchase. Companies that do not own all of the data sets may purchase and receive the maps and digital grids over the owned data sets only.
• Data Provided:
  Maps: Regional Isostatic Correction, Total Isostatic Correction, Isostatic Anomaly
  Magnetic Tape: Mapped data on 6,000-foot grid interval
  Report
• Cost: $15,000

· Isostatic Anomaly Survey on Regional Coverage Map: 18K gif file

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Northeast Gulf Survey and Interpretation

Data

• Survey Size: 17,450 line miles covering 50,000 square miles
• Line Spacing: 3 x 10 miles between 2,000 and 6,000 ft. water depths; 6 x 20 miles for water depths greater than 6,000 feet
• Survey Date: 1984
• Data Provided:
  Maps (scales 1:192,000 and 1:500,000): Bathymetry, Terrain-corrected Bouguer Gravity, Free-Air Gravity, Total Magnetic Intensity
  Profiles of each survey line: bathymetry, observed and processed gravity, Eötvös correction, total magnetic intensity, base station magnetics
  Magnetic Tape: one-minute samples of observed and processed data, including navigation
  Interpretation: structural and tectonic interpretation of basement and sedimentary structures based on gravity, magnetic and published geologic and seismic data
  Maps: High-Density Basement, Magnetic Basement, Tectonic Interpretation, Reduced-to-Pole Total Magnetic Intensity (RTP), Regional Gravity, Residual Gravity, Second Vertical Derivatives (SVD) of RTP Magnetics and Residual Gravity
  Magnetic Tape: mapped data on 6,000-foot grid interval of observed and interpreted data
  Report
• New Pricing:
  Call for quotation, partial and complete purchases available.

· Northeast Gulf Survey on Regional Coverage Map: 13K gif file
· Northeast Gulf Detailed Layout Map: 111K gif file

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Offshore California Marine Gravity Surveys

Data

• Survey Areas: Point Arena, Santa Maria, Eel River Basin
• Data Provided:
  2-D Bouguer Gravity
  Free-Air Gravity
  Bathymetry
  Shipline Location

· Offshore California Marine Gravity Map: 17K gif file

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Offshore Western United States - California (NOAA Data, OSS Surveyor) Marine Gravity and Magnetic Survey

Data

• Survey Size: Areas A and B
  Gravity, 11,115 line miles
  Magnetics, 33,453 line miles
• Data Spacing: Areas A and B
  Primary line spacings are 5 and 10 miles
• Data Provided:
  Hand-Mapped Terrain-Corrected Bouguer Gravity Map
  Hand-Mapped Total Magnetic Intensity Map with Earth's normal field removed
• Total Cost: Areas A and B - $19,900

Interpretation

• Available upon request

· Offshore Western U.S. Map: 46K jpg file

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Schafer/Teledyne Gulf of Mexico Underwater Gravity Surveys

Data

• Project Size: 124,574 underwater stations
  Data sets include: 32,609 stations offshore Texas; 53,465 stations offshore Louisiana; 38,500 stations offshore Mississippi, Alabama, Florida
• Project Summary:
  Digitized principal facts for all of the Schafer/Teledyne underwater gravity data in the Gulf of Mexico. The digital data include station gravity and water depth at each station. The gravity value, water depth and location of each station have been extensively cross-checked, and reduced values have been carefully compared against the original maps in order to obtain a data set that is internally consistent and accurate. A total of 124,574 stations are available.
  Terrain corrections were computed for Hayford-Bowie Zones A-L (from station location to radius of 28.8 km) using a 3,000-foot water depth grid compiled from the Schafer surveys, EDCON's bathymetric data base and published bathymetric data. These terrain corrections were computed using bathymetric surface fitting techniques which provide accurate consistent terrain effect computations.
• Data Provided: The digital data set includes both complete Bouguer and surface equivalent free-air gravity values. Free-air gravity has been computed using the method adopted by the Defense Mapping Agency so that the data are compatible with EDCON and other shipborne gravity surveys.
• Cost: Ownership of the Schafer data is a prerequisite for the purchase of the digital data. The price for a single purchase of 50,000 or more stations is $0.30 per station. Partial purchase of fewer stations is at the following rates (minimum purchase is 2,000 stations): $0.50 per station for the first 10,000 stations; $0.40 per station for the next 10,000 stations; $0.30 per station for all stations over 20,000

· Schafer / Teledyne Underwater Gravity Survey on Regional Coverage Map: 16K gif file

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Texas-Louisiana Continental Shelf Top of Salt Interpretation

Data

• Survey Area: 51,732 square miles
• Station Spacing: 3,734 feet
• Date: 1971
• Data Provided:
  Maps (scale 1:96,000): Top of Salt, Residual Gravity, Calculated Gravity, Second-Order Residual Gravity, Regional Gravity (1" = 20,000')
  Magnetic Tape: grid of all mapped data and Bouguer Gravity
  Report: digitized data, regional field, negative residual field, computer technique of fitting gravity data, top of salt, calculated gravity, second-order residual gravity, areas requiring further study
  Interpretation: 3-D inverse model, integrated gravity/geologic structural interpretation
• New Pricing:
• Conditions of Sale:
  First 3,000 square miles, $4.00/square mile
  3,000 - 10,000 square miles, $2.75/square mile
  Over 10,000 square miles, $2.00/square mile
  1,000 square mile minimum purchase
  Ownership of Schafer Underwater Gravity coverage is a prerequisite for purchase of the Top of Salt Interpretation

· Texas/Louisiana Continental Shelf Survey on Regional Coverage Map: 16K gif file
· Texas/Louisiana Continental Shelf Detailed Layout Map: 19K gif file

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Western and Central Gulf of Mexico Survey and Interpretation

Data

• Survey Size: 80,000 line miles
• Line Spacing: 1 x 5 mile grid over 2/3 of survey area. 3 x 10 mile and 6 x 20 mile coverage in some of the deeper water areas - see map.
• Survey Date: 1984
• Data Provided:
  Maps (scales 1:192,000 and 1:500,000): Bathymetry, Terrain-corrected Bouguer Gravity, Free-Air Gravity, Total Magnetic Intensity
  Profiles of each survey line: bathymetry, observed and processed gravity, Eötvös correction, total magnetic intensity, base station magnetics
  Magnetic Tape: one-minute samples of observed and processed data, including navigation
  Interpretation: structural and tectonic interpretation of basement and sedimentary structures based on gravity, magnetic and published geologic and seismic data
  Maps: High-Density Basement, Magnetic Basement, Tectonic Interpretation, Reduced-to-Pole Total Magnetic Intensity (RTP), Regional Gravity, Residual Gravity, Second Vertical Derivatives (SVD) of RTP Magnetics and Residual Gravity
  Magnetic Tape: mapped data on 6,000-foot grid interval of observed and interpreted data
  Report
• New Pricing:
  Call for quotation, partial and complete purchases available.

· Western and Central Gulf of Mexico Survey on Regional Coverage Map: 13K gif file
· Western and Central Gulf of Mexico Detailed Layout Map: 1300K pdf file

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