Geologic map of Alaska

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What does this data set describe?

Title: Geologic map of Alaska
Abstract:
Digital compilation and reinterpretation of published and unpublished geologic mapping of Alaska.
  1. How might this data set be cited?
    Wilson, Frederic H., Labay, Keith, Shew, Nora, and Hults, Chad P., 2015, Geologic map of Alaska:.

    Online Links:

    This is part of the following larger work.

    Wilson, Frederic H., Hults, Chad P., Mull, Charles G., and Karl, Susan M., 2015, Geologic map of Alaska: US Geological Survey Scientific Investigations Map SIM 3340.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: 172.0
    East_Bounding_Coordinate: -130.0
    North_Bounding_Coordinate: 72.0
    South_Bounding_Coordinate: 51.2
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 2015
    Currentness_Reference: publication date
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: Vector Digital Data Set (Polygon)
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      This is a Vector data set. It contains the following vector data types (SDTS terminology):
      • G-polygon (245562)
    2. What coordinate system is used to represent geographic features?
      The map projection used is NAD 1983 Alaska Albers (ESRI Full Name: NAD_1983_Alaska_Albers).
      Projection parameters:
      Standard_Parallel: 55.0
      Standard_Parallel: 65.0
      Longitude_of_Central_Meridian: -154.0
      Latitude_of_Projection_Origin: 50.0
      False_Easting: 0.0
      False_Northing: 0.0
      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest 0.6096
      Ordinates (y-coordinates) are specified to the nearest 0.6096
      Planar coordinates are specified in Meter
      The horizontal datum used is D_North_American_1983.
      The ellipsoid used is GRS_1980.
      The semi-major axis of the ellipsoid used is 6378137.0.
      The flattening of the ellipsoid used is 1/298.257222101.
  7. How does the data set describe geographic features?
    AKStategeol_poly
    Characteristics of the geologic unit are coded in the polygon attribute table. The table includes the following items: CLASS, QCLASS, SOURCE, NSACLASS, NSASUB, NSAMOD, SOURCECLASS, STATE_SYMBOL, STATE_LABEL, STATE_LABEL2, STATE_UNITNAME, AGE_RANGE, and SEQUENCE. (Source: this data set)
    CLASS
    Unique numeric code assigned to a geologic unit from an original source map. Number is unique only within a given quadrangle and specific to SOURCE. (Source: this data set)
    Formal codeset
    Codeset Name:nsaunits (provided as geodatabase table, Filemaker database, Filemaker runtime, and CSV and DBF files)
    Codeset Source:this data set
    QCLASS
    Subdivision of attribute NSACLASS providing more detailed Quaternary classification. Field QCLASS is a key field for linking to field QCLASS in table nsaqkey. (Source: this data set)
    Formal codeset
    Codeset Name:nsaunits (provided as geodatabase table, Filemaker database, Filemaker runtime, and CSV and DBF files)
    Codeset Source:this data set
    SOURCE
    Unique code assigned to each source; uses the 2-letter quadrangle code and a three digit number. By default, 001 is reserved for the topographic map or other source of hydrologic spatial data for each quadrangle. Field SOURCE is a key field and links to SOURCE in table nsarefs. (Source: this data set)
    Formal codeset
    Codeset Name:nsarefs (provided as geodatabase table, Filemaker database, Filemaker runtime, and CSV and DBF files)
    Codeset Source:this data set
    NSACLASS
    Regional numeric code assigned to similar geologic units. Field NSACLASS is a key field and links to field NSACLASS in tables nsaage, nsakey, nsalith, nsarefs, and nsasetting. NSACLASS is also a 1:many relationship with NSACLASS in table nsaunits. (Source: this data set)
    Formal codeset
    Codeset Name:nsakey (provided as geodatabase table, Filemaker database, Filemaker runtime, and CSV and DBF files)
    Codeset Source:this data set
    NSASUB
    Same coding as NSACLASS, but used to define the bedrock unit beneath surficial deposits. Not universally populated. (Source: this data set)
    Formal codeset
    Codeset Name:nsakey (provided as geodatabase table, Filemaker database, Filemaker runtime, and CSV and DBF files)
    Codeset Source:this data set
    NSAMOD
    Indicates if a geologic unit is altered, contact metamorphosed, or has a queried unit assignment. Some maps show contact metamorphosed areas as separate units; these units are assigned a NSACLASS for the appropriate protolith and have 'HFS' selected as NSAMOD value. If only a few polygons of a geologic unit are altered or contact metamorphosed, then the NSAMOD value is set for those polygons only. Queried units, Tk? versus Tk for example, have the same NSACLASS, but Tk? will have NSAMOD = 'Q'. (Source: this data set)
    ValueDefinition
    {Null Value / Empty Field Entry}Unit is not altered, contact metamorphosed, or queried.
    ALTHydrothermally altered, nonspecific
    ALT, QHydrothermally altered, nonspecific, and queried(?)
    ALT-SERSericitic alteration
    HFSContact metamorphism, nonspecific
    HFS, QContact metamorphism, nonspecific, and queried
    QQueried (?) geologic unit
    SOURCECLASS
    Concatenated field that uniquely identifies a given source map (SOURCE) and geologic unit (CLASS). Field SOURCECLASS is a key field that links to field SOURCE_CLASS in table nsaunits. (Source: this data set)
    Formal codeset
    Codeset Name:nsaunits (provided as geodatabase table, Filemaker database, Filemaker runtime, and CSV and DBF files)
    Codeset Source:this data set
    STATE_SYMBOL
    Number defining symbol color in WPGCMYKG.style for ArcGIS to display the detailed digital geologic map in AKStategeol.mxd. (Source: this data set)
    Range of values
    Minimum:0
    Maximum:992
    STATE_LABEL
    Same as STATE_LABEL2 but uses special characters for using FGDCGeoAge font to display the symbols for geologic time periods. (Source: this data set) } represents Mesozoic; ^ Triassic; | Paleozoic; * Pennsylvanian; _ Cambrian; = preCambrian; and < Proterozoic.
    STATE_LABEL2
    Geologic unit label used in the Description of Map Units and detailed version of the state map. Label is in standard text font and does not use special characters. Px is used for Proterozoic and IP for Pennsylvanian. (Source: this data set)
    Formal codeset
    Codeset Name:gen_state_link (provided as Filemaker database, Filemaker runtime, CSV and DBF files)
    Codeset Source:this data set
    STATE_UNITNAME
    Unit name as used in the Description of Map Units (Source: this data set)
    Formal codeset
    Codeset Name:gen_state_link (provided as Filemaker database, Filemaker runtime, and CSV and DBF files)
    Codeset Source:this data set
    AGE_RANGE
    Age range of the map unit in the Description of Map Units, does not necessarily match the units on the printed generalized map. The combining of DMU units for the generalized map may have created longer time intervals for the units. (Source: this data set) Describes the geologic age interval of the geologic unit as used in the Description of Map Units (DMU). Information obtained from gen_state_link (provided as Filemaker databse, Filemaker runtime, and CSV and DBF files)
    SEQUENCE
    A sorting code using a letter for lithologic type and then a number. Used to place the unit in age order. Matches the order given in the Description of Map Units. (Source: this data set) A is unconsolidated units; B is sedimentary rocks; C is volcanic rocks; D is plutonic rocks, E is metamorphic rocks, and F is tectonic units or assemblages.
    AKStategeol_arc
    Characteristics of linear features, which include various types of faults, stratigraphic contacts, and other line types. Lineations and dikes are stored in separate feature classes, but contain similar attributes. Items in AKStategeol_arc include the following items: ARC_CODE, ARC_PARA1, SOURCE, LINEID, LINE_TYPE, LEFT_LABEL, and RIGHT_LABEL. (Source: this data set)
    ARC_CODE
    ARC_CODE is a positive integer value in the arc attribute table. Values range discontinuously from 0 to 99. Values match one-for-one with LINE_TYPE. (Source: this data set)
    ValueDefinition
    1Stratigraphic contact; location certain
    2Stratigraphic contact; location approximate
    3Stratigraphic contact; inferred; queried
    4Normal fault; location certain; if arc-para1 = 1, then upthrown side is on right-hand side
    5Normal fault; location approximate; if arc-para1 = 1, then upthrown side is on right-hand side
    6Normal fault; location inferred, queried; if arc-para1 = 1, then upthrown side is on right-hand side
    7Shoreline or riverbank; arc-para1 = 1 designates single-sided stream, typically used in areas of braiding
    8Internal contact or phase change in the source map.
    9Boundary of altered zone or hornfels
    10Thrust fault; location certain; teeth on right from origin. ARC_PARA1 is dip of the fault plane, if known. A negative number indicates overturned fault.
    11Thrust fault; location approximate; teeth on right from origin. ARC_PARA1 is dip of the fault plane, if known. A negative number indicates overturned fault.
    12Thrust fault; location inferred, queried; teeth on right from origin
    13Moraine or till margin (scour) on bedrock
    14Caldera or crater rim
    15Ice contact (glacier limit)
    18Internal contact
    19Moraine limit having tics on right side from origin. ARC_PARA1 = 1 indicates the moraine is submerged.
    28Caldera or crater rim, inferred or concealed
    30Fault with unknown offset; location certain
    31Fault with unknown offset; location approximate
    32Fault with unknown offset; location inferred
    34Terrace, erosional, or wave-cut scarp; digitize with water on right from origin
    35High-angle reverse fault; certain location; teeth on right from origin; arc-para1 is angle of thrusting, if known
    36High-angle reverse fault; certain approximate; teeth on right from origin; arc-para1 is angle of thrusting, if known
    37High-angle reverse fault; certain inferred; teeth on right from origin; arc-para1 is angle of thrusting, if known
    48Moraine crest
    50Dikes and sills (used in feature class AKStategeol_dike)
    51Concealed contact
    52Concealed normal fault; if arc-para1 = 1, then upthrown side is on right-hand side
    53Concealed thrust fault; teeth on right from origin. ARC_PARA1 is dip of the fault plane, if known. A negative number indicates overturned fault.
    54Concealed high-angle reverse fault
    55Concealed normal fault having right lateral oblique slip
    56Concealed normal fault having left lateral oblique slip
    57Concealed right lateral fault
    58Concealed left lateral fault
    59Concealed shear zone
    60Concealed fault with unknown offset
    71Normal fault; location certain; having right lateral oblique slip; if arc-para1 = 1, then upthrown side is on right-hand side
    72Normal fault; location approximate; having right lateral oblique slip; if arc-para1 = 1, then upthrown side is on right-hand side
    73Normal fault; location certain; having left lateral oblique slip; if arc-para1 = 1, then upthrown side is on right-hand side
    74Normal fault; location approximate; having left lateral oblique slip; if arc-para1 = 1, then upthrown side is on right-hand side
    75Normal fault; location inferred or queried; having left lateral oblique slip; if arc-para1 = 1, then upthrown side is on right-hand side
    76Normal fault; location inferred or queried; having right lateral oblique slip; if arc-para1 = 1, then upthrown side is on right-hand side
    87Right lateral fault; location certain
    88Right lateral fault; location approximate
    89Right lateral fault; location inferred, queried
    90Left lateral fault; location certain
    91Left lateral fault; location approximate
    92Left lateral fault; location inferred, queried
    94Shear zone, location certain
    96Shear zone; location inferred
    97Scratch line used where polygon on source map was not closed, or limit of mapping
    98International border
    99Bounding neat line of 1:250,000 scale quadrangle
    ARC_PARA1
    Used as a modifier for ARC_CODE (Source: this data set) See ARC_CODE attribute definitions for ARC_PARA1 definition
    SOURCE
    Unique code assigned to each source; uses the 2-letter quadrangle code and a three digit number. By default, 001 is reserved for the topographic map or other source of hydrologic spatial data for each quadrangle. Field SOURCE is a key field for linking to field SOURCE in table nsarefs. (Source: this data set)
    Formal codeset
    Codeset Name:nsarefs (provided as geodatabase table, Filemaker database, Filemaker runtime, and CSV and DBF files)
    Codeset Source:this data set
    LINEID
    LINEID provides additional attributes for some faults and glacial moraines. For faults, LINEID identifies the fault system the feature belongs to. For moraines, LINEID identifies the moraine or glacial limit. LINEID is an 8 character alpha-numeric code following this naming convention. The first letter is 'f' if the feature is a fault, or 'm' if a moraine. The second and third characters are alpha abbreviations for the fault system, region, or glaciation. These abbreviations are defined below. The final 4 numbers in LINEID are identifiers which further subdivide the line's description. Field LINEID is a key field for linking to field LINEID in table LINEID. (Source: this data set)
    ValueDefinition
    fBRBorder Ranges fault system
    fCHfaults in the Chugach Mountains region
    fCSCoast Mountains orogen
    fDEDenali fault system
    fFWFairweather-Chugach-Ragged Mountain fault system
    fKBKobuk fault system
    fKGKugruk
    fKTKaltag fault system
    fLALaurentia region, Kandik River area of Alaska
    fLGLivengood region
    fNABrooks Range region
    fTCTikchik-Susitna region
    fTITintina fault system
    fTKTalkeetna suture zone
    fWRWrangellia region
    fYAfaults in the Yakutat block region, south of the Fairweather-Chugach-Ragged Mountain fault system
    fYKYukon-Kuskokwim region
    fYTYukon-Tanana region
    hideused for symbolizing small scale maps; identifies faults not to be drawn in areas of high density
    hide2same as 'hide' but feature to be drawn as ARC_CODE = 2 if map is to show contacts.
    mLWLate Wisconsin glaciation
    LEFT_LABEL
    Geologic unit on the left side of the line feature. (Source: this data set) See polygon attribute STATE_LABEL2.
    RIGHT_LABEL
    Geologic unit on the right side of the line feature. (Source: this data set) See polygon attribute STATE_LABEL2.
    LINE_TYPE
    Descriptive name for ARC_CODE (Source: this data set) Brief description of ARC_CODE
    AKStategeol_dike
    Line features representing dikes and sills (Source: this data set)
    ARC_CODE
    same as attribute ARC_CODE in AKStategeol_arc feature class (Source: this data set)
    ValueDefinition
    50Dikes and sills
    SOURCE
    Unique code assigned to each source; uses the 2-letter quadrangle code and a three digit number. Same as attribute SOURCE in AKStategeol_arc and AKStategeol_poly. (Source: this data set)
    Formal codeset
    Codeset Name:nsarefs (available as geodatabase table, Filemaker database, Filemaker runtime, and CSV and DBF files)
    Codeset Source:this data set
    CLASS
    Unique numeric code assigned to a geologic unit from the original source map. Number is unique only within a given quadrangle and specific to SOURCE. Not universally populated. (Source: this data set)
    Formal codeset
    Codeset Name:nsaunits (provided as geodatabase table, Filemaker database, Filemaker runtime, and CSV and DBF files)
    Codeset Source:this data set
    NSACLASS
    Regional numeric code assigned to similar units. Not universally populated. (Source: this data set)
    Formal codeset
    Codeset Name:nsakey (provided as a geodatabase table, Filemaker database, Filemaker runtime, and CSV and DBF files)
    Codeset Source:this data set
    LINE_TYPE
    Descriptive name for ARC_CODE (Source: this data set) Dikes and sills
    AKStategeol_lineament
    Line features representing lineaments (Source: this data set)
    ARC_CODE
    same as attribute ARC_CODE in AKStategeol_arc feature class (Source: this data set) All lineaments have ARC_CODE = 93
    SOURCE
    Unique code assigned to each source; uses the 2-letter quadrangle code and a three digit number. Same as attribute SOURCE in AKStategeol_arc and AKStategeol_poly. (Source: this data set)
    Formal codeset
    Codeset Name:nsarefs (provided as geodatabase table, Filemaker database, Filemaker runtime, and CSV and DBF files)
    Codeset Source:this data set
    LINE_TYPE
    Descriptive name for ARC_CODE (Source: this data set) Lineament
    lineid
    lineid is a table in AKStategeol.gdb containing additional information about some faults and moraines. (Source: this data set)
    LINEID
    LINEID provides additional attributes for some faults and moraines. LINEID is the keyfield for linking to AKStategeol_arc. (Source: this data set) Describes fault system or region this feature is found. See description of LINEID for AKStategeol_arc.
    LINE_NAME
    Descriptive name of fault system, region, or moraine (Source: this data set) Descriptive name of fault system, region, or moraine
    nsaage
    Table containing geologic age information for each unique NSACLASS value. Provides composite maximum and minimum age assignments for a given NSACLASS. A modified version of International Union of Geological Sciences (IUGS) International Chronostratigraphic Chart or radiometric dating were used to determine age attributes. (Source: this data set)
    NSACLASS
    key field to link to AKStategeol_poly (Source: this data set)
    Formal codeset
    Codeset Name:nsakey (provided as geodatabase table, Filemaker database, Filemaker runtime, and CSV and DBF files)
    Codeset Source:this data set
    MIN_MA
    Minimum age in millions of years, determined either from IUGS or radiometric dating. (Source: this data set)
    Range of values
    Minimum:0
    Maximum:1600
    Units:Ma, million years
    MAX_MA
    Maximum age in millions of years, determined either from IUGS or radiometric dating. (Source: this data set)
    Range of values
    Minimum:0.0117
    Maximum:2500
    Units:Ma, million years
    TYPE
    Defines whether the age assignment is relative, if based on stratigraphic position, or absolute, if based on radiometric dating. The default value is 'Relative'. (Source: this data set)
    ValueDefinition
    AbsoluteAge assignment is based on radiometric dating
    RelativeAge assignment is based on stratigraphic position. Default value.
    AGE_COM
    Age_comments (Source: this data set) Free text
    MIN_EON
    The minimum or youngest age assignment for the eon of the unit, based on geologic interpretation. (Source: this data set)
    Formal codeset
    Codeset Name:International Chronostratigraphic Chart
    Codeset Source:IUGS
    MIN_ERA
    The minimum or youngest age assignment for the era of the unit, based on geologic interpretation. (Source: this data set)
    Formal codeset
    Codeset Name:International Chronostratigraphic Chart
    Codeset Source:IUGS
    MIN_PERIOD
    The minimum or youngest age assignment for the period of the unit, based on geologic interpretation. (Source: this data set)
    Formal codeset
    Codeset Name:International Chronostratigraphic Chart
    Codeset Source:IUGS
    MIN_EPOCH
    The minimum or youngest age assignment for the epoch of the unit, based on geologic interpretation. (Source: this data set)
    Formal codeset
    Codeset Name:International Chronostratigraphic Chart
    Codeset Source:IUGS
    MIN_AGE
    The minimum or youngest age assignment for the age of the unit, based on geologic interpretation. (Source: this data set)
    Formal codeset
    Codeset Name:International Chronostratigraphic Chart
    Codeset Source:IUGS
    MAX_EON
    The maximum or oldest age assignment for the eon of the unit, based on geologic interpretation. (Source: this data set)
    Formal codeset
    Codeset Name:International Chronostratigraphic Chart
    Codeset Source:IUGS
    MAX_ERA
    The maximum or oldest age assignment for the era of the unit, based on geologic interpretation. (Source: this data set)
    Formal codeset
    Codeset Name:International Chronostratigraphic Chart
    Codeset Source:IUGS
    MAX_PERIOD
    The maximum or oldest age assignment for the period of the unit, based on geologic interpretation. (Source: this data set)
    Formal codeset
    Codeset Name:International Chronostratigraphic Chart
    Codeset Source:IUGS
    MAX_EPOCH
    The maximum or oldest age assignment for the epoch of the unit, based on geologic interpretation. (Source: this data set)
    Formal codeset
    Codeset Name:International Chronostratigraphic Chart
    Codeset Source:IUGS
    MAX_AGE
    The maximum or oldest age assignment for the age of the unit, based on geologic interpretation. (Source: this data set)
    Formal codeset
    Codeset Name:International Chronostratigraphic Chart
    Codeset Source:IUGS
    FULL_MIN
    Concatenation of fields MIN_EON, MIN_ERA, MIN_PERIOD, MIN_EPOCH, and MIN_AGE. (Source: this data set)
    Formal codeset
    Codeset Name:International Chronostratigraphic Chart
    Codeset Source:IUGS
    CMIN_AGE
    The most precise minimum age coded; derived from FULL_MIN field. (Source: this data set)
    Formal codeset
    Codeset Name:International Chronostratigraphic Chart
    Codeset Source:IUGS
    FULL_MAX
    Concatenation of fields MAX_EON, MAX_ERA, MAX_PERIOD, MAX_EPOCH, and MAX_AGE. (Source: this data set)
    Formal codeset
    Codeset Name:International Chronostratigraphic Chart
    Codeset Source:IUGS
    CMAX_AGE
    The most precise maximum age coded; derived from FULL_MAX field. (Source: this data set)
    Formal codeset
    Codeset Name:International Chronostratigraphic Chart
    Codeset Source:IUGS
    nsakey
    Table containing labels and colors applied to the map. The table also includes a brief description of the geologic unit. Key field is NSACLASS. (Source: this data set)
    REC_NO
    unique numeric identifier (Source: this data set)
    Range of values
    Minimum:1
    Maximum:1461
    SYMBOL
    Symbol number for wpgcmykg.style; used for symbolizing polygons for the detailed state geologic map; based on NSACLASS (Source: this data set)
    Range of values
    Minimum:0
    Maximum:995
    NSACLASS
    Regional numeric code assigned to similar units. (Source: this data set)
    Range of values
    Minimum:90
    Maximum:20000
    LABEL
    Map labels used for regional maps, which may be different from the generalized and/or detailed state maps. (Source: this data set) free text
    DESCRIPTION
    Brief summary of the regional geologic unit, which may be different from the generalized and/or detailed state maps. (Source: this data set) free text
    nsalith
    Table containing the lithologic coding for each regional geologic unit. Geologic units are comprised of more than one rock type, therefore lithology to NSACLASS is a many-to-one relationship. Each lithology is described in a 5 tiered hierarchy and is given a rank based on abundance. (Source: this data set)
    RECORD_NO
    unique numeric identifier (Source: this data set)
    Range of values
    Minimum:1
    Maximum:4027
    NSACLASS
    Regional numeric code assigned to similar geologic units. Key field to link to AKStategeol_poly. (Source: this data source)
    Range of values
    Minimum:99
    Maximum:12950
    LITH1
    Highest level lithologic classification. Text field. (Source: this data set)
    Formal codeset
    Codeset Name:Lithologic data dictionary
    Codeset Source:GUIDE_TO_DIGITAL_DATABASE_FILES_(readme), Appendix 1
    LITH2
    Second level lithologic classification. LITH2 is based on value of LITH1. Text field. (Source: this data set)
    Formal codeset
    Codeset Name:Lithologic data dictionary
    Codeset Source:GUIDE_TO_DIGITAL_DATABASE_FILES_(readme), Appendix 1
    LITH3
    Third level lithologic classification. LITH3 is based on value of LITH2. Text field. (Source: this data set)
    Formal codeset
    Codeset Name:Lithologic data dictionary
    Codeset Source:GUIDE_TO_DIGITAL_DATABASE_FILES_(readme), Appendix 1
    LITH4
    Fourth level lithologic classification. LITH4 is based on value of LITH3. Text field. (Source: this data set)
    Formal codeset
    Codeset Name:Lithologic data dictionary
    Codeset Source:GUIDE_TO_DIGITAL_DATABASE_FILES_(readme), Appendix 1
    LITH5
    Fifth level lithologic classification. LITH5 is based on value of LITH4. Text field. (Source: this data set)
    Formal codeset
    Codeset Name:Lithologic data dictionary
    Codeset Source:GUIDE_TO_DIGITAL_DATABASE_FILES_(readme), Appendix 1
    TOTALLITH
    Concatenation of LITH1, LITH2, LITH3, LITH4, and LITH5. This field allows for searches on any level of the lithologic hierarchy. (Source: this data set)
    Formal codeset
    Codeset Name:Lithologic data dictionary
    Codeset Source:GUIDE_TO_DIGITAL_DATABASE_FILES_(readme), Appendix 1
    LOWEST
    Copy of the lith field with the most specific part of the lithologic assignment. (Source: this data set)
    Formal codeset
    Codeset Name:Lithologic data dictionary
    Codeset Source:GUIDE_TO_DIGITAL_DATABASE_FILES_(readme), Appendix 1
    FORM
    Description of lithologic form. (Source: this data set)
    Formal codeset
    Codeset Name:Lithform Data Dictionary
    Codeset Source:GUIDE_TO_DIGITAL_DATABASE_FILES_(readme), Appendix 2
    RANK
    Indicates how much of the geologic map unit this lithology represents. (Source: this data set)
    ValueDefinition
    MajorGreater than or equal to 33 percent
    Minorbetween 10 and 33 percent
    Incidentalless than 10 percent
    Indeterminate (major)Abundance of this lithology is not defined. The term 'major' is part of the attribute to insure inclusive searches for major rock types, as rock types listed in the indeterminate category could be a major component of a geologic map unit. These may be eliminated from search results by explicitly omitting 'Indeterminate' from the query results.
    PERCENT
    Optional field containing an estimate of percentage of the unit that this lithology represents. This information is rarely available in Alaska. (Source: this data set)
    Range of values
    Minimum:5
    Maximum:100
    LITH_COMMENT
    comment field (Source: this data set) free form text
    NSAQKEY
    Similar to NSAKEY except it subdivides the Quaternary surficial deposits by assigning color symbols and labels to the Quaternary units. (Source: this data set)
    SYMBOL
    Symbol number for wpgcmykg.style; used for symbolizing polygons based on Quaternary units, QCLASS (Source: this data set)
    Range of values
    Minimum:0
    Maximum:974
    QCLASS
    Subdivision of attribute NSACLASS providing more detailed Quaternary units. Key field linking to AKStategeol_poly. (Source: this data set)
    Formal codeset
    Codeset Name:nsaunits (provided as geodatabase table, Filemaker database, Filemaker runtime, and CSV and DBF files)
    Codeset Source:this data set
    NSACLASS
    Regional numeric code assigned to similar geologic units. (Source: this data set)
    Formal codeset
    Codeset Name:nsakey (provided as geodatabase table, Filemaker database, Filemaker runtime, and CSV and DBF files)
    Codeset Source:this data set
    UNIT_LABEL
    Geologic unit label for statewide Quaternary map (Source: this data set) Quaternary surficial map unit label.
    GEOLOGIC_UNIT
    Brief description of the surficial map unit (Source: this data set) free text
    NSAREFS
    Reference citation for source map and/or other publication used to build AKStategeol data set. (Source: this data set)
    REFNUM
    unique numeric identifier (Source: this data set)
    Range of values
    Minimum:1
    Maximum:1272
    SOURCE
    Unique code assigned to each source; uses the 2-letter 1:250,000 scale quadrangle code and a three digit number. By default, 001 is reserved for the topographic map or other source of hydrologic spatial data for each quadrangle. If a source map extends into multiple quadrangles, it has been assigned a source code for each quadrangle covered. (Source: this data set) Unique code assigned to each source that uses the two letter 1:250,000 scale quadrangle code and a three digit number.
    REFERENCE
    Reference citation (Source: this data set) Reference citation written in USGS style.
    NSASETTING
    Geologic setting for each unique NSACLASS value (Source: this data set)
    NSACLASS
    Regional numeric code assigned to similar geologic units. (Source: this data set)
    Range of values
    Minimum:98
    Maximum:20000
    SETTING
    Description of geologic setting for each unique NSACLASS. (Source: this data set) free text
    NSAUNITS
    Table derived from the central database, NSAUNITS. Contains brief abstracts of the unit descriptions from each SOURCE map, which have been classified into regional and statewide units. (Source: this data set)
    QUADRANGLE
    Name of 1:250,000 scale quadrangle. The name of the Mount McKinley 1:250,000 scale quadrangle was changed to Denali in September 2015. The records for this area are duplicated as both Mount McKinley(MM) and Denali(DN). (Source: this data set) free text
    MAP_UNIT
    Geologic unit label from the SOURCE map. (Source: this data set) free text
    UNIT_NAME
    Map unit name from the SOURCE map. (Source: this data set) free text
    AGE
    Geologic age of the unit as given on the SOURCE map. (Source: this data set) free text
    DESCRIPTION
    Abstracted version of the unit description from the SOURCE map. Focus on lithology and important relationships as described on the SOURCE map. (Source: this data set) free text
    ROCK_CLASS
    General classification of geologic unit. For mixed units, the dominant category is given. (Source: this data set) Igneous, sedimentary, metamorphic, unconsolidated, or melange. For mixed units, the dominant category is given.
    FOSSIL
    Brief notes on any fossil control mentioned on the SOURCE map. (Source: this data set) free text
    RADIOMETRIC_AGE
    Brief notes on radiometric ages mentioned on the SOURCE map. (Source: this data set) free text
    SOURCE
    Unique code assigned to each source; used the 2-letter code for 1:250,000 scale quadrangles, and a three digit number. By default, 001 is used for the topographic map or other source of hydrologic spatial data for each quadrangle. Numbers above 100 indicate sources that were not captured digitally. (Source: this data set) free text
    CLASS
    Unique numeric code assigned to each geologic unit on a SOURCE map. Unique only within a given quadrangle and specific to each SOURCE. (Source: this data set)
    Range of values
    Minimum:0
    Maximum:55240
    SOURCE_CLASS
    Concatenation of fields SOURCE and CLASS. (Source: this data set) free text
    NSACLASS
    Regional numeric code assigned to like geologic units. Link to many of the other databases or tables. (Source: this data set)
    Range of values
    Minimum:90
    Maximum:12950
    NSAMOD
    Indicates if geologic unit is altered, contact metamorphosed, or has a queried unit assignment. (Source: this data set)
    ValueDefinition
    ALTHydrothermally altered, nonspecific
    ALT-BIOBiotite alteration
    ALT-POTPotassic alteration
    ALT-SERSericitic alteration
    HFSContact metamorphism, nonspecific
    QQueried (?) geologic unit
    QCLASS
    Regional numeric code assigned to similar surficial units. (Source: this data set)
    Range of values
    Minimum:0
    Maximum:4900
    NSASUB
    Used to define the bedrock unit (NSACLASS) underlying surficial deposits. Not universally populated. (Source: this data set)
    Range of values
    Minimum:0
    Maximum:8626
    radiometric_ages
    Point feature class with radiometric age data for samples analyzed by K/Ar, 40Ar/39Ar, Rb/Sr, fission-track, and other methods, excluding U/Pb determinations. Created from Radiometric database, which is provided as a Filemaker database, Filemaker runtime, and DBF and CSV files. (Source: this data set)
    REC_NO
    Unique numeric identifier for this data set (Source: this data set)
    Range of values
    Minimum:1
    Maximum:6108
    SAMPLE
    Sample number/identifier (Source: this data set) free text
    QUAD
    Name of 1:250,000 scale quadrangle (Source: this data set) free text
    LATITUDE
    Latitude given in decimal degrees, NAD27 (Source: this data set)
    Range of values
    Minimum:50.266667
    Maximum:70.953333
    Units:degree
    LONGITUDE
    Longitude given in decimal degrees, NAD27 (Source: this data set)
    Range of values
    Minimum:-179.127
    Maximum:179.433333
    Units:degree
    ROCK_TYPE
    Rock type of sample dated (Source: this data set) free text
    MINERAL
    Mineral or phase dated (Source: this data set) free text
    METHOD
    Dating method used (Source: this data set)
    ValueDefinition
    40/39Argon-argon dating
    40/39 AverageAverage of multiple 40Ar/39Ar ages
    40/39 High temp. frac.40Ar/39Ar high temperature fraction
    40/39 Isochron40Ar/39Ar isochron age
    40/39 Plateau40Ar/39Ar plateau age
    40/39 Total Fusion40Ar/39Ar total fusion age
    Fission-trackFission track dating
    K/ArPotassium-argon dating
    Lu/HfLutetium-hafnium dating
    Pb-alphaLead-alpha dating
    Rb/SrRubidium-strontium dating
    Re/OsRhenium-osmium dating
    Sm/NdSamarium-neodymium dating
    U-Th/HeUranium-thorium / helium dating; uranium-helium dating
    COMMENT
    Comments about the sample or analysis. (Source: this data set) free text
    REFERENCE
    Reference citations for the age determination (Source: this data set) free text
    AGE
    Reported age in millions of years (Source: this data set)
    Range of values
    Minimum:-30.5
    Maximum:3258
    Units:Ma, million years
    ERROR
    Analytical error for the age calculation, if reported (Source: this data set)
    Range of values
    Minimum:0
    Maximum:1300
    Units:Ma, million years
    PLATEAU_AGE
    40Ar/39Ar plateau age, if reported (Source: this data set)
    Range of values
    Minimum:-0.0103
    Maximum:832.5
    Units:Ma, million years
    PLATEAU_ERROR
    Analytical error for the 40Ar/39Ar plateau age, if reported (Source: this data set)
    Range of values
    Minimum:0.0008
    Maximum:21.8
    Units:Ma, million years
    ISOCHRON_AGE
    40Ar/39Ar isochron age, if reported (Source: this data set)
    Range of values
    Minimum:-0.019
    Maximum:196.6
    Units:Ma, million years
    ISOCHRON_ERROR
    Analytical error for the 40Ar/39Ar isochron age, if reported (Source: this data set)
    Range of values
    Minimum:0.0015
    Maximum:62.6
    Units:Ma, million years
    FUSION_AGE
    40Ar/39Ar total fusion age, if reported (Source: this data set)
    Range of values
    Minimum:-0.038
    Maximum:1352.4
    Units:Ma, million years
    FUSION_ERROR
    Analytical error for the 40Ar/39Ar total fusion age, if reported (Source: this data set)
    Range of values
    Minimum:0.001
    Maximum:129.8
    Units:Ma, million years
    u_pb_ages
    Point feature class of U-Pb age data for samples analyzed by uranium-lead methods. Created from u-pb database, which is provided as a Filemaker database, Filemaker runtime, and DBF and CSV files. (Source: this data set)
    REC_NO
    unique numeric identifier for this data table (Source: this data set)
    Range of values
    Minimum:1
    Maximum:1389
    SAMPLE
    Sample number/identifier (Source: this data set) free text
    QUAD
    Name of 1:250,000 scale quadrangle (Source: this data set) free text
    LATITUDE
    Latitude given in decimal degrees, NAD27 (Source: this data set)
    Range of values
    Minimum:51.376667
    Maximum:68.37
    Units:degree
    LONGITUDE
    Longitude given in decimal degrees, NAD27 (Source: this data set)
    Range of values
    Minimum:-174.696667
    Maximum:179.375
    Units:degree
    ROCK_TYPE
    Rock type of sample dated (Source: this data set) free text
    MINERAL
    Mineral or phase dated (Source: this data set) free text
    METHOD
    Dating method used (Source: this data set)
    ValueDefinition
    ICPMSInductively coupled plasma-mass spectrometry
    SHRIMPSensitive high resolution ion microprobe
    TIMSThermal ionization mass spectrometry
    TIMS-multigrainThermal ionization mass spectrometry multi-grain
    TIMS-singlegrainThermal ionization mass spectrometry single grain
    U/ThUranium-thorium dating
    U/PbUranium-lead dating
    COMMENT
    Comments about the sample or analysis. (Source: this data set) free text
    REFERENCE
    Reference citations for the age determination (Source: this data set) free text
    PREFERRED_AGE
    Interpreted best age based on the data; reported in millions of years (Source: this data set)
    Range of values
    Minimum:0.0051
    Maximum:2108
    Units:Ma, million years
    ERROR
    Analytical error for the preferred age, if reported (Source: this data set)
    Range of values
    Minimum:0
    Maximum:725
    Units:Ma, million years
    SIGMA
    Number of standard deviations of reported analytical error (Source: this data set) Either 1 or 2 standard deviations
    AGE_TYPE
    Additional description of the interpreted age or sample. (Source: this data set) free text
    AGE_EVENT
    Additional description of the interpreted age. (Source: this data set) free text
    F206PB_238U
    206Pb/238U age (Source: this data set)
    Range of values
    Minimum:0.0051
    Maximum:1977
    Units:Ma, million years
    F206PB_238U_ERROR
    206Pb/238U age error (Source: this data set)
    Range of values
    Minimum:0.06
    Maximum:20
    Units:Ma, million years
    F207PB_235U
    207Pb/235U age (Source: this data set)
    Range of values
    Minimum:28.9
    Maximum:2054
    Units:Ma, million years
    F207PB_235U_ERROR
    207Pb/235U age error (Source: this data set)
    Range of values
    Minimum:0.1
    Maximum:20
    Units:Ma, million years
    F207PB_206PB
    207Pb/206Pb age (Source: this data set)
    Range of values
    Minimum:15
    Maximum:2258
    Units:Ma, million years
    F207PB_206PB_ERROR
    207Pb/206Pb age error (Source: this data set)
    Range of values
    Minimum:1
    Maximum:399
    Units:Ma, million years
    F208PB_232TH
    208Pb/232Th age (Source: this data set)
    Range of values
    Minimum:3
    Maximum:2408
    Units:Ma, million years
    F208PB_232TH_ERROR
    208Pb/232Th age error (Source: this data set)
    Range of values
    Minimum:6
    Maximum:12
    Units:Ma, million years
    F206PB_204PB
    206Pb/204Pb age (Source: this data set)
    Range of values
    Minimum:21.5
    Maximum:6115
    Units:Ma, million years
    F206PB_204PB_ERROR
    206Pb/204Pb age error (Source: this data set) field is empty
    UPPER_INTERCEPT
    Upper concordia intercept (Source: this data set)
    Range of values
    Minimum:70
    Maximum:2450
    Units:Ma, million years
    UPPER_ERROR
    Upper concordia intercept error (Source: this data set)
    Range of values
    Minimum:1
    Maximum:470
    Units:Ma, million years
    LOWER_INTERCEPT
    Lower concordia intercept (Source: this data set)
    Range of values
    Minimum:-304
    Maximum:1371
    Units:Ma, million years
    LOWER_ERROR
    Lower concordia intercept error (Source: this data set)
    Range of values
    Minimum:0.8
    Maximum:699
    Units:Ma, million years

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    U.S. Geological Survey, Alaska Science Center
    Attn: Frederic H. Wilson
    Research Geologist
    4210 University Drive
    Anchorage, AK
    US

    907-786-7448 (voice)
    fwilson@usgs.gov

Why was the data set created?

This data set represents part of a systematic effort to release geologic map data for the United States in a uniform manner. Geologic data in this data set has been compiled from a wide variety of sources, published and unpublished, ranging from state and regional geologic map to field mapping.

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 2)
    The geology for each of the 153 1:250,000 scale quadrangles in Alaska was compiled from many different sources. Data capture has been ongoing since 1995. Linework was hand digitized from materials of various media and scale. The arcs and polygons were attributed, and topology was checked. Data is archived as ARC/Info coverages.
    Date: 2015 (process 2 of 2)
    The geology data from the 153 quadrangle coverages were combined to create the detailed map feature classes in AKStatewidegeol.gdb
  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?
    Many types of source materials of varying scales were used to compile this data set. Sources include previously published maps, unpublished mapping, and air photo interpretation, and reflects more than a century of work in Alaska. Vector features were mostly digitized either by digitizing on screen or on a large format digitizing tablet. Vectors and polygons were attributed and checked. Topology rules were checked.
  2. How accurate are the geographic locations?
    Data is presented for use at a nominal scale of 1:250,000.
  3. How accurate are the heights or depths?
    not applicable.
  4. Where are the gaps in the data? What is missing?
    The data set AKStategeol.gdb consists of arc, polygon, and point features depicting the geology of Alaska in both detailed and generalized versions. The detailed state map geologic units are described in the Description of Map Units (DMU) found in the accompanying pamphlet. The features for the generalized version were derived from the detailed features; the generalized version is used for the printed version of the state map. A separate metadata file is provided for the generalized version. The AKStategeol.gdb also includes many tables which contain additional information and can be linked to either the arc or polygon features. The information in the tables were derived from a set of related Filemaker databases which contain additional information. The native Filemaker database files and a stand-alone Filemaker_Runtime file, along with CSV and DBF files are provided with this publication. The features in AKStategeol.gdb are also provided as shapefiles.
  5. How consistent are the relationships among the observations, including topology?
    The geologic data consists of attributed arcs and polygons. Each polygon has a coded attribute designating the mapped geologic unit. Faults, stratigraphic contacts, dikes, lineations and other linear features are represented as arcs. When a fault is also a stratigraphic contact, only a single arc is present. Dangling arcs may be present (fault, dike, lineation, etc.).

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. Users are advised to read the data set's metadata thoroughly to understand appropriate use and data limitations. Acknowledgment of the U.S. Geological Survey would be appreciated in products derived from these data.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey
    MS902 Box 25286 Denver Federal Center
    Lakewood, CO
    U.S.A.

    1-888-ASK-USGS (voice)
  2. What's the catalog number I need to order this data set?
  3. What legal disclaimers am I supposed to read?
    This publication was prepared by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, expressed or implied, or assumes any legal liability or responsibility for the accuracy, product, or process disclosed in this report, or represents that its use would not infringe privately owned rights. Reference therein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof.
  4. How can I download or order the data?

Who wrote the metadata?

Dates:
Last modified: 26-Oct-2015
Metadata author:
U.S. Geological Survey, Alaska Region
Attn: Nora B. Shew
Geologist
4210 University Drive
Anchorage, AK
US

907-786-7445 (voice)
907-786-7401 (FAX)
nshew@usgs.gov
Metadata standard:
FGDC Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
Generated by mp version 2.9.32 on Mon Oct 26 17:23:18 2015