Identification_Information:
  Citation:
    Citation_Information:
      Originator: Geoffrey C. Collins
      Originator: G. Wesley Patterson
      Originator: James W. Head
      Originator: Robert T. Pappalardo
      Originator: Louise M. Prockter
      Originator: Baerbel K. Lucchitta
      Originator: Jonathan P. Kay
      Publication_Date: 2013
      Title: Global Geologic Map of Ganymede, SIM-3237
      Edition: 1
      Geospatial_Data_Presentation_Form: vector digital data
      Publication_Information:
        Publication_Place: Denver, CO
        Publisher: U.S. Geological Survey
      Online_Linkage: http://pubs.usgs.gov/sim/3237/
      Online_Linkage: http://www.usgs.gov/pubprod/
  Description:
    Abstract:
      Ganymede is the largest satellite of Jupiter, and its icy surface has been formed through a variety of of impact cratering, tectonic, and possibly cryovolcanic processes.  The history of Ganymede can be divided into three distinct phases: an early phase dominated by impact cratering and mixing of non-ice materials in the icy crust, a phase in the middle of its history marked by great tectonic upheaval, and a late quiescent phase characterized by a gradual drop in heat flow and further impact cratering.  Images of Ganymede suitable for geologic mapping were collected during the flybys of Voyager 1 and Voyager 2 (1979), as well as during the Galileo mission in orbit around Jupiter (1995-2003).  This map represents a synthesis of our understanding of Ganymede geology after the conclusion of the Galileo mission.

      The two fundamental classes of material units on Ganymede are dark materials and light materials.  The dark/light distinction is based on sharp relative albedo contrasts at terrain boundaries, rather than on absolute albedo, as several other types of surface modification (e.g., crater rays, polar caps) change the absolute albedo within these terrain classes.  Dark materials cover 35% of Ganymedeâs surface, with almost the entire remainder of the surface covered by light materials.

      Dark materials are heavily cratered, though not as heavily cratered as the surface of the neighboring satellite Callisto, suggesting that dark materials cannot be a primordial surface.  At high resolution, dark materials are dominated by the downslope movement of loose dark regolith within impact craters and on the sides of bright ridges and hummocks.  These observations suggest that dark materials are covered by a thin lag deposit of dark regolith derived by sublimation of a more ice-rich crust below.  Dark materials commonly exhibit sets of concentric arcuate structures known as furrows.  Furrows may be the remnants of ancient multi-ring impact basins, similar to intact impact basins on Callisto such as Valhalla and Asgard.

      Light materials crosscut dark materials and exhibit a lower impact crater density, demonstrating that they were formed later.  Light materials are subdivided into an intricate patchwork of crosscutting lineaments called grooves, mixed with areas of relatively smooth terrain.  At high resolution, most light materials are dominated by extensional faulting.  Even light materials that appear to be smooth at low resolution are marked at high resolution by sets of parallel lineaments of apparent tectonic origin.  There is an open question on the extent to which light terrain is formed by cryovolcanic flooding of dark material with brighter ice, versus tectonic destruction of preexisting surface features and exposure of brighter subsurface ice in fault scarps; it is certainly possible that both of these processes play important roles in the formation of light materials.  Not all tectonic activity on Ganymede has led to the formation of light material ö some dark material is cut by extensional faults without exhibiting a major change in albedo, while reticulate material is cut by two sets of tectonic lineaments and is transitional in albedo between adjacent light and dark materials.

      The other material units found on Ganymede were created by several types of impact features, ranging from impact craters, to viscously relaxed impact features called palimpsests, to the large impact basin Gilgamesh in the southern hemisphere.

    Purpose: 
       Much has been learned about Ganymede's impact cratering, tectonic, and possibly cryovolcanic processes since the Voyager flybys, primarily during and following the Galileo Mission at Jupiter (December 1995-September 2003). Our mapping incorporates this new understanding to assist in map unit definition and provide a global synthesis of Ganymede's geology.

    Supplemental_Information:
      > Patterson, G.W., Collins, G.C., Head, J.W., and 4 others, 2010, Global geological mapping of Ganymede: Icarus, v. 207, p. 845-867.
      > Shoemaker, E.M., Lucchitta, B.K., Wilhelms, D.E., and 2 others, 1982, The geology of Ganymede, in: Satellites of Jupiter (Morrison, D., ed.), Univ. of Arizona Press, p. 435-520.
      > Pappalardo, R.T., Collins, G.C., Head, J.W., and 6 others, 2004, Geology of Ganymede, in: Jupiter (Bagenal, F., Dowling, T., McKinnon, W., eds.), Cambridge Univ. Press, p. 363-396.

  Time_Period_of_Content:
    Time_Period_Information:
      Multiple_Dates/Times:
        Single_Date/Time:
          Calendar_Date: 2006
        Single_Date/Time:
          Calendar_Date: 2013
    Currentness_Reference: publication date
  Status:
    Progress: Complete
    Maintenance_and_Update_Frequency: None planned
  Spatial_Domain:
    Bounding_Coordinates:
      West_Bounding_Coordinate: 0
      East_Bounding_Coordinate: 360
      North_Bounding_Coordinate: 90
      South_Bounding_Coordinate: -90
  Keywords:
    Theme:
      Theme_Keyword_Thesaurus: NASA
      Theme_Keyword: Geologic Map
      Theme_Keyword: Ganymede
      Theme_Keyword: Galilean satellites
      Theme_Keyword: Jupiter
      Theme_Keyword: Voyager 1
      Theme_Keyword: Voyager 2
      Theme_Keyword: Galileo
      Theme_Keyword: Cassini
      Theme_Keyword: New Horizons
    Place:
      Place_Keyword_Thesaurus: Gazatteer of Planetary Nomenclature (http://planetarynames.wr.usgs.gov)
      Place_Keyword: Ganymede
      Place_Keyword: Jupiter
  Access_Constraints: None
  Use_Constraints: None
  Point_of_Contact:
    Contact_Information:
      Contact_Person_Primary:
        Contact_Person: Jim Skinner
        Contact_Organization: USGS
      Contact_Address:
        Address_Type: mailing address
        Address: 2255 North Gemini Drive
        City: Flagstaff
        State_or_Province: AZ
        Postal_Code: 86001
        Country: USA
      Contact_Voice_Telephone: 928-556-7100
      Contact_Electronic_Mail_Address: jskinner@usgs.gov
  Security_Information:
    Security_Classification: Unclassified
  Native_Data_Set_Environment: Esri ArcMap 10.0
Data_Quality_Information:
  Attribute_Accuracy:
    Attribute_Accuracy_Report: All attributes were verified by displaying the lines in both the database and the spatial coverage and they are believed to be logically consistent.
  Logical_Consistency_Report: These data are believed to be logically consistent. Line geometry is topologically clean.
  Completeness_Report: Competed at the given scale for publication by USGS
  Positional_Accuracy:
    Horizontal_Positional_Accuracy:
      Horizontal_Positional_Accuracy_Report: The final map was generalized and scaled to be commensurate with a 1:15,000,000 map scale, although map component compilation was at a larger scale.   Overall, the geologic map product is only as accurate as the 2005 basemap created by the USGS which contains kilometer errors.
      Quantitative_Horizontal_Positional_Accuracy_Assessment:
        Horizontal_Positional_Accuracy_Explanation: Becker, T. et al., 2001. Final Digital Global Maps of Ganymede, Europa, and Callisto, In Lunar and Planetary Science XXXII, Abstract #2009, Lunar and Planetary Institute, Houston (CD-ROM).
      Quantitative_Horizontal_Positional_Accuracy_Assessment:
        Horizontal_Positional_Accuracy_Explanation: http://www.lpi.usra.edu/meetings/lpsc2001/pdf/2009.pdf
  Lineage:
    Source_Information:
      Source_Citation:
        Citation_Information:
          Originator: Tammy Becker
          Originator: Brent Archinal
          Originator: Timothy R. Colvin
          Originator: Mert Davies
          Originator: A. Gitlin
          Originator: Randy L. Kirk
          Originator: Lynn Weller
          Publication_Date: 2001
          Title: Final Digital Global Maps of Ganymede, Europa, and Callisto
          Edition: 1
          Geospatial_Data_Presentation_Form: remote-sensing image
          Publication_Information:
            Publication_Place: Houston, TX
            Publisher: Lunar and Planetary Science XXXII
          Online_Linkage: http://www.lpi.usra.edu/meetings/lpsc2001/pdf/2009.pdf
    Process_Step:
      Process_Description: Relative age relationships of mapped units were determined based on crosscutting relationships and differences in crater density.  Dark cratered material (dc) is crosscut by grooves to form dark lineated material (dl).  Dark materials and reticulate material are crosscut by light materials.  Light materials are divided into three broad age categories based on crosscutting relationships.  The youngest (lg3, ls3, li3) light material units are not crosscut by any other light units, while the oldest (lg1, ls1, li1) are crosscut by all adjacent light units.  Intermediate age light material units (lg2, ls2, li2) are crosscut by the youngest units, and intermediate units in turn crosscut the oldest units.  Dark lineated (dl) and reticulate (r) material sometimes share common groove spacing, morphology, and orientation with adjacent old light materials (lg1, ls1, li1), indicating that they may have formed contemporaneously.  Palimpsests are divided into ancient palimpsests (p1), which are crosscut by light material, young palimpsests (p2), which overlie light material, and undivided palimpsests (pu), which do not come in contact with light material and thus crosscutting relationships cannot be used for relative age determination.  The p2 palimpsests Epigeous and Zakar overlie all ages of light materials, Teshub overlies undivided light materials (l) and is cut by young light grooved material (lg3), and Hathor overlies undivided light material (l) while its secondary craters overlie old light subdued material (ls1) and intermediate light grooved material (lg2).  All basin materials (br, bs, bi) overlie all ages of light materials.  Some degraded crater materials (c1) are crosscut by dark lineated (dl) and light materials, while other degraded crater materials overlie light materials.  Partially degraded and fresh crater materials (c2 and c3) overlie all other material units.
Spatial_Data_Organization_Information:
  Direct_Spatial_Reference_Method: Vector
  Point_and_Vector_Object_Information:
    SDTS_Terms_Description:
      SDTS_Point_and_Vector_Object_Type: G-polygon
      Point_and_Vector_Object_Count: 3046
Spatial_Reference_Information:
  Horizontal_Coordinate_System_Definition:
    Geographic:
      Latitude_Resolution: 0.01
      Longitude_Resolution: 0.01
      Geographic_Coordinate_Units: Decimal degrees
    Geodetic_Model:
      Horizontal_Datum_Name: D_Ganymede_2000
      Ellipsoid_Name: Ganymede_2000_IAU_IAG
      Semi-major_Axis: 2632345.0
      Denominator_of_Flattening_Ratio: infinity
  Vertical_Coordinate_System_Definition:
    Altitude_System_Definition:
      Altitude_Resolution: 0.000003
      Altitude_Encoding_Method: Explicit elevation coordinate included with horizontal coordinates
Entity_and_Attribute_Information:
  Detailed_Description:
    Entity_Type:
      Entity_Type_Label: CraterRims
    Entity_Type_Definition: Crater rims
    Attribute:
      Attribute_Label: Shape_Length
      Attribute_Definition: Length of crater rim perimeter in meters
  Detailed_Description:
    Entity_Type:
      Entity_Type_Label: Depressions
    Entity_Type_Definition: Known depressions
    Attribute:
      Attribute_Label: Type
      Attribute_Definition: depression
  Detailed_Description:
    Entity_Type:
      Entity_Type_Label: Domes
    Entity_Type_Definition: Known domes
    Attribute:
      Attribute_Label: Type
      Attribute_Definition: dome
  Detailed_Description:
    Entity_Type:
      Entity_Type_Label: Secondary Craters
    Entity_Type_Definition: Known secondary craters
    Attribute:
      Attribute_Label: Type
      Attribute_Definition: secondary craters
  Detailed_Description:
    Entity_Type:
      Entity_Type_Label: Furrows
    Entity_Type_Definition: Known furrows
    Attribute:
      Attribute_Label: Type
      Attribute_Definition: furrow
  Detailed_Description:
    Entity_Type:
      Entity_Type_Label: GroovesRepresentative
    Entity_Type_Definition: Known representative grooves
    Attribute:
      Attribute_Label: Type
      Attribute_Definition: groove
  Detailed_Description:
    Entity_Type:
      Entity_Type_Label: GeologyUnits
    Entity_Type_Definition: Geologic unit type
    Attribute:
      Attribute_Label: UnitName
      Attribute_Definition: Basins, Bright Materials, Crater Materials, Dark Materials, Palimpsests, Reticulate
  Detailed_Description:
    Entity_Type:
      Entity_Type_Label: GeologicContacts
    Entity_Type_Definition: Geologic contact type
    Attribute:
      Attribute_Label: Type
      Attribute_Definition: certain, approximate, interior
Distribution_Information:
  Distributor:
    Contact_Information:
      Contact_Organization_Primary:
        Contact_Organization: U.S. Geological Survey
      Contact_Address:
        Address_Type: mailing address
        Address: Box 25286 Federal Center
        City: Denver
        State_or_Province: CO
        Postal_Code: 80225
        Country: USA
      Contact_Electronic_Mail_Address: ktanaka@usgs.gov
  Resource_Description: Downloadable Data
  Standard_Order_Process:
    Digital_Form:
      Digital_Transfer_Information:
        Format_Name: Esri File GeoDatabase
        Format_Version_Number: ArcGIS 9.3
        Format_Specification: GIS
        File_Decompression_Technique: zip
        Transfer_Size: 200
      Digital_Transfer_Option:
        Online_Option:
          Computer_Contact_Information:
            Network_Address:
              Network_Resource_Name: http://www.usgs.gov/pubprod/
              Network_Resource_Name: http://pubs.usgs.gov/sim/3237
          Access_Instructions: Web browser
    Fees: n/a
    Ordering_Instructions: Digital download using a web browser.
  Technical_Prerequisites: GIS software
  Available_Time_Period:
    Time_Period_Information:
      Single_Date/Time:
        Calendar_Date: 2012
Metadata_Reference_Information:
  Metadata_Date: 20120229
  Metadata_Review_Date: 2012
  Metadata_Contact:
    Contact_Information:
      Contact_Person_Primary:
        Contact_Person: Trent Hare
        Contact_Organization: USGS
      Contact_Address:
        Address_Type: mailing address
        Address: 2255 North Gemini Drive
        City: Flagstaff
        State_or_Province: AZ
        Postal_Code: 86001
        Country: USA
      Contact_Voice_Telephone: 928-556-7126
      Contact_Electronic_Mail_Address: thare@usgs.gov
  Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata
  Metadata_Standard_Version: FGDC-STD-001-1998
  Metadata_Time_Convention: local time
  Metadata_Access_Constraints: None
  Metadata_Use_Constraints: None
  Metadata_Security_Information:
    Metadata_Security_Classification: Unclassified
  Metadata_Extensions:
    Online_Linkage: http://www.esri.com/metadata/esriprof80.html
    Profile_Name: Esri Metadata Profile