Identification_Information:  
  Citation:  
    Citation_Information:  
      Originator: Ronald E. Sweeney
      Originator: Robert P. Kucks
      Originator: Patricia L. Hill  
      Originator: Carol A. Finn  
      Publication_Date: 2006  
      Title:  
        Aeromagnetic and Gravity Surveys in Afghanistan: 
        A Web Site for Distribution of Data  
      Geospatial_Data_Presentation_Form: raster digital data  
      Series_Information:  
        Series_Name: U.S. Geological Survey Open-File Report  
        Issue_Identification: Open-File Report 2006-1204  
      Publication_Information:  
        Publication_Place: Denver, Colorado, USA  
        Publisher: U.S. Geological Survey  
      Online_Linkage: http://pubs.usgs.gov/of/2006/1204  
  Description:  
    Abstract: 
      Aeromagnetic data were digitized from aeromagnetic maps created from
      aeromagnetic surveys flown in southeastern and southern Afghanistan
      in 1966 by PRAKLA, Gesellschaft für praktische Lagerstättenforschung
      GmbH, Hannover, Germany, on behalf of the "Bundesanstalt für
      Bodenforschung", Hannover, Germany.  The digitization was done along
      contour lines, followed by interpolation of the data along the original
      survey flight-lines.  Survey and map specifications can be found in two
      project reports, "prakla_report_1967.pdf" and "bgr_report_1968.pdf",
      made available in this open-file report.

      Gravity data were collected from 1645 locations in Afghanistan between
      the years 1911 and 1967 in the 4 surveys identified in the external
      author index file report, "aif.txt", which is made available in this
      open-file report.
    Purpose: 
      The purpose of the aeromagnetic surveys was for a more detailed
      investigation of the sedimentary basins in the southeastern and
      southern part of Afghanistan, as well as the localization of possibly
      existing magnetic deposits.

      The purposes of the gravity surveys can be found in the individual
      survey reports listed in the external author index file report
      ("aif.txt"), which is made available in this open-file report.
  Time_Period_of_Content:  
    Time_Period_Information:  
      Range_of_Dates/Times:  
        Beginning_Date: 1911  
        Ending_Date: 1967  
    Currentness_Reference: survey dates  
  Status:  
    Progress: complete  
    Maintenance_and_Update_Frequency: none planned  
  Spatial_Domain:  
    Bounding_Coordinates:  
      West_Bounding_Coordinate: 60.8° E. longitude  
      East_Bounding_Coordinate: 71.6° E. longitude  
      North_Bounding_Coordinate: 38.1° N. latitude  
      South_Bounding_Coordinate: 29.4° N. latitude  
  Keywords:  
    Place:  
      Place_Keyword_Thesaurus: none  
      Place_Keyword: Afghanistan  
    Theme:  
      Theme_Keyword_Thesaurus: none  
      Theme_Keyword: geophysical data 
      Theme_Keyword: gravity data 
      Theme_Keyword: aeromagnetic data 
      Theme_Keyword: aeromagnetic grid 
  Access_Constraints: none  
  Use_Constraints: none  
  Point_of_Contact:  
    Contact_Information:  
      Contact_Person_Primary:  
        Contact_Person: Ronald Sweeney  
        Contact_Organization: U.S. Geological Survey  
      Contact_Address:  
        Address_Type: mailing address  
        Address:  
          Box 25046, MS964  
          Denver Federal Center  
        City: Denver  
        State_or_Province: CO  
        Postal_Code: 80225-0046  
        Country: USA  
      Contact_Voice_Telephone: 303-236-1389  
      Contact_Electronic_Mail_Address: rsweeney@usgs.gov  
  Native_Data_Set_Environment:  
    These grids and databases were created using USGS processing programs on  
    a UNIX system and on a PC using Geosoft/OASIS montaj application 
    software.  
Data_Quality_Information:  
  Attribute_Accuracy:  
    Attribute_Accuracy_Report: 
      The digital data are Geosoft databases and grids, which were created 
      from the original gravity and digitized aeromagnetic data identified
      in this report.  Data accuracies thus coincided with the original
      survey/data processing accuracies, which can be located in the reports
      listed in the abstract above.  The final aeromagnetic grid interval
      of 400 m was chosen as representative. 
        
      The data in the original grids have been processed using formulas and  
      methods that are not usually documented but that represent  
      industry standard practices for airborne data reduction.  
  
  Logical_Consistency_Report: 
      
    Standard industry practices of the time were followed in data  
    collection and processing.  
  
  Completeness_Report:  
    Areas with no data in the aeromagnetic grid are flagged with 
    Geosoft dummy values.
  Positional_Accuracy:  
    Horizontal_Positional_Accuracy: 
      Horizontal_Positional_Accuracy_Report:
        Horizontal position of the survey aircraft used to collect data 
        being integrated into the composite grid were determined by 
        varying standard aircraft navigation aids.
    Vertical_Positional_Accuracy:  
      Vertical_Positional_Accuracy_Report: 
        The individual aeromagnetic surveys that make up this data 
        set were flown at various fixed barometric altitudes.
  Lineage:  
    Process_Step: 
      Process_Description: 
        See the report, "prakla_report_1967.pdf", for a description of the 
        aeromagnetic data processing steps.  See the reports located in the 
        external author index file report, "aif.txt", for a description of 
        the gravity data processing steps. 
      Process_Date: 1911-1967
    Process_Step:  
      Process_Description: 
        Each of the original aeromagnetic survey maps were digitized
        along coutour lines, followed by interpolation of the data
        along the original survey flight-lines. The initial aeromagnetic
        grids for each survey were constructed using a minimum curvature 
        algorithm and a spacing appropriate for the scale of the digitized 
        map. 
 
        The digitized aeromagnetic data for all surveys were then assembled 
        and regridded to the final grid cell size of 400 m using a minimum 
        curvature algorithm.  
      Process_Date: 1966-2006
Entity_and_Attribute_Information:  
  Overview_Description:  
    Entity_and_Attribute_Overview:  
      One aeromagnetic grid and two databases (aeromagnetic and gravity)
      are included in this report:  
  
      GDR_clmag.grd - Geosoft binary grid format  
      Final southeastern Afghanistan aeromagnetic anomaly grid from 
      digitized data.
  
      GDR_clmag.gdb - Geosoft database format  
      Final southeastern Afghanistan aeromagnetic anomaly database from
      digitized data.  
  
      afgrav.gdb - Geosoft database format  
      Final Afghanistan gravity database from 4 surveys.  
  
      The 2 databases above are also provided in the report in an additional 
      format:  Geosoft XYZ.  (See the files, "readme_GDR_datafiles.pdf" and
      "readme_gravity_datafiles.pdf", in this open-file report for details.)  
  
      The grid projection specifications for the above grid and databases are 
      provided in detail in this open-file report.
    Entity_and_Attribute_Detail_Citation: Open-File Report 2006-1204  
  Detailed_Description:  
    Entity_Type:  
      Entity_Type_Label: gridded aeromagnetic  
      Entity_Type_Definition: Ascii real number value  
      Entity_Type_Definition_Source: well-established geophysical data quantities  
    Attribute:  
      Attribute_Label: Residual total intensity of Earth's magnetic field  
      Attribute_Definition:  
        Gridded values found in file 'GDR_clmag.grd' 
 
        The total magnetic value minus a geomagnetic reference field, which 
        is a long-wavelength regional magnetic field.  The most commonly 
        used reference field is calculated from the theoretical International 
        Geomagnetic Reference Field (IGRF).  
  
        The individual aeromagnetic survey data were digitized from original  
        maps at original flight elevation surfaces.  These digitized data
        were then combined and gridded at 400 m final grid cell size using
        a minimum curvature algorithm.  
  
      Attribute_Definition_Source: 
        see: Nettleton, L.L., 1971, Elementary Gravity and Magnetics for  
        Geologists and Seismologists: Society of Exploration Geophysicists  
        Monograph Series No. 1, p. 83-87.  
  
      Attribute_Domain_Values:  
        Range_Domain:  
          Range_Domain_Minimum: -1053.571 
          Range_Domain_Maximum: 1128.036 
          Attribute_Units_of_Measure: nanoteslas  
  Detailed_Description:  
    Entity_Type:  
      Entity_Type_Label: aeromagnetic anomaly database
      Entity_Type_Definition: Ascii real number value  
      Entity_Type_Definition_Source: well-established geophysical data quantities  
    Attribute:  
      Attribute_Label: Residual total intensity of Earth's magnetic field
      Attribute_Definition:  
        Aeromagnetic anomaly values found in file 'GDR_clmag.gdb' 
 
        The total magnetic value minus a geomagnetic reference field, which 
        is a long-wavelength regional magnetic field.  The most commonly 
        used reference field is calculated from the theoretical International 
        Geomagnetic Reference Field (IGRF).  
  
      Attribute_Definition_Source: 
        see: Nettleton, L.L., 1971, Elementary Gravity and Magnetics for  
        Geologists and Seismologists: Society of Exploration Geophysicists  
        Monograph Series No. 1, p. 83-87. 
 
      Attribute_Domain_Values:  
        Range_Domain:  
          Range_Domain_Minimum: -1075.0
          Range_Domain_Maximum: 1115.0
          Attribute_Units_of_Measure: nanoteslas  
  Detailed_Description:  
    Entity_Type:  
      Entity_Type_Label: gravity anomaly database
      Entity_Type_Definition: Ascii real number value  
      Entity_Type_Definition_Source: well-established geophysical data quantities  
    Attribute:  
      Attribute_Label: Complete Bouguer gravity anomaly 
      Attribute_Definition:  
        Gridded values found in file 'afghan.gdb' 
 
        The complete-Bouguer gravity anomaly database for Afghanistan.  
  
      Attribute_Definition_Source: 
        see: Nettleton, L.L., 1971, Elementary Gravity and Magnetics for  
        Geologists and Seismologists: Society of Exploration Geophysicists  
        Monograph Series No. 1. 
 
        see: http://pubs.usgs.gov/fs/fs-0239-95/fs-0239-95.pdf   
      Attribute_Domain_Values:  
        Range_Domain:  
          Range_Domain_Minimum: -464.4  
          Range_Domain_Maximum: -35.7
          Attribute_Units_of_Measure: milliGals  
Distribution_Information:  
  Distributor:  
    Contact_Information:  
      Contact_Person_Primary:  
        Contact_Person: Ron Sweeney  
        Contact_Organization: U. S. Geological Survey  
      Contact_Address:  
        Address_Type: mailing address  
        Address:  
          Box 25046, MS 964  
          Denver Federal Center  
        City: Denver  
        State_or_Province: CO  
        Postal_Code: 80225  
        Country: USA  
      Contact_Voice_Telephone: 303-236-1389  
      Contact_Electronic_Mail_Address: rsweeney@usgs.gov  
  Resource_Description: USGS Open-File Report 2006-1204 
  Distribution_Liability:  
    Although all data published in the grids and databases 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 these data or related materials.  
  
    Any use of trade, product, or firm names is for descriptive purposes  
    only and does not imply endorsement by the U.S. Government.  
  Standard_Order_Process:  
    Digital_Form:  
      Digital_Transfer_Information:  
        Format_Name:  
          grd - gridded data files
          gdb - database files  
          txt - ASCII description files  
        Transfer_Size: 57.0 Mbytes is the largest file size  
      Digital_Transfer_Option:  
        Online_Option:  
          Computer_Contact_Information:  
            Network_Address:  
              Network_Resource_Name: http://pubs.usgs.gov/of/2006/1204
    Fees: no charge for online downloads  
Metadata_Reference_Information:  
  Metadata_Date: 20060530
  Metadata_Contact:  
    Contact_Information:  
      Contact_Person_Primary:  
        Contact_Person: Ron Sweeney  
        Contact_Organization: U.S. Geological Survey  
      Contact_Address:  
        Address_Type: mailing address  
        Address:  
          U.S. Geological Survey  
          Box 25046 Mail Stop 964  
          Denver Federal Center  
        City: Denver  
        State_or_Province: CO  
        Postal_Code: 80225  
        Country: USA  
      Contact_Voice_Telephone: 303-236-1389  
      Contact_Electronic_Mail_Address: rsweeney@usgs.gov  
  Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata  
  Metadata_Standard_Version: FGDC-STD-001-1998