Data tables related to geology and gold mineralization in the Richardson district, east-central Alaska

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What does this data set describe?

Title:
Data tables related to geology and gold mineralization in the Richardson district, east-central Alaska
Abstract:
This report describes the results of geologic mapping and sample analysis from the Richardson district, east-central Alaska.
Supplemental_Information:
Attribute information for the following tables (entities) is included in this metadata file under the "Entity_and_Attribute_Information" section. Each layer is listed and described in detail under its own heading starting "Entity_Type_Label." Tables include:
table1   grab samples, approximate locations, assigned rock types and analyses
table2    Modal mineralogy of gneisses
table3    Estimated modal mineral abundances (volume %)
table4    XRF major oxide and normative values for gneiss samples
table5    XRF major and minor element results for amphibolite samples
table6    XRF major oxide and normative values for igneous rock samples
table7    Trace element compositions (in ppm) of igneous rocks
table8    Samples employed for Geothermometry and Geobarometry
table9    Average microprobe data of mineral assemblages
table10    Fluid inclusion samples, locations, and assay values
table11    Fluid inclusion data and estimated fluid parameters
table12    Comparison between Bald Knob, Democrat, Ryan Lode fluid inclusion data
table13    Interpreted 40Ar/39Ar ages (in Ma)
table14    Ages of geologic events
table15    40Ar/39Ar step-heating results and data
  1. How should this data set be cited?

    Graham, G.E., and Jozwik, Diana, 2007, Data tables related to geology and gold mineralization in the Richardson district, east-central Alaska: Raw Data File RDF 2007-2, State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys, Fairbanks, AK USA.

    Online Links:

    Other_Citation_Details: 32 pp.

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -146.4829
    East_Bounding_Coordinate: -146.1133
    North_Bounding_Coordinate: 64.8802
    South_Bounding_Coordinate: 64.3246

  3. What does it look like?

  4. Does the data set describe conditions during a particular time period?

    Beginning_Date: 1999
    Ending_Date: 2002
    Currentness_Reference: publication date

  5. What is the general form of this data set?

    Geospatial_Data_Presentation_Form: tabular digital data, report

  6. How does the data set represent geographic features?

    1. How are geographic features stored in the data set?

    2. What coordinate system is used to represent geographic features?

      Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.0001. Longitudes are given to the nearest 0.0001. Latitude and longitude values are specified in Decimal degrees.

      The horizontal datum used is North American Datum of 1927.
      The ellipsoid used is Clarke 1866.
      The semi-major axis of the ellipsoid used is 6378137.
      The flattening of the ellipsoid used is 1/298.25722210088.

  7. How does the data set describe geographic features?

    table1.csv
    List of grab samples, approximate locations, assigned rock types and analyses. (Source: Garth Graham)

    Sample
    Items in the Sample# field. (Source: Garth Graham)

    A unique sample identifier

    UTMX
    Easting for UTM Zone 6, NAD 27 (Source: Garth Graham)

    Range of values
    Minimum:525000
    Maximum:542000
    Units:meters

    UTMY
    Northing for UTM Zone 6, NAD 27 (Source: Garth Graham)

    Range of values
    Minimum:7133090
    Maximum:7195200
    Units:meters

    Rock type
    Description of rock sample (Source: Garth Graham)

    Description of rock type

    Mag. Susc. (*10^-3 SI)
    Magnetic susceptibility made with a Kappameter model KT-6 magnetic susceptibility meter. (Source: Garth Graham)

    Range of values
    Minimum:-0.05
    Maximum:1.3
    Units:SI

    T.S.
    Thin section (Source: Garth Graham)

    Marked "X" if a thin section was made.

    P.S.
    Polished section (Source: Garth Graham)

    Marked "X" if a polished section was made.

    WRA
    Whole rock analysis (Source: Garth Graham)

    Marked "X" if whole rock analysis was performed on sample.

    Geotherm
    microprobe and/or geothermobarometric analysis (Source: Garth Graham)

    Marked "X" if microprobe or geothermobarometric analysis was performed on sample.

    FI
    Fluid inclusion study (Source: Garth Graham)

    Marked "X" if fluid inclusion analysis was performed on sample.

    Ar/Ar
    40Ar/39Ar radiometric dating (Source: Garth Graham)

    Marked "X" if argon dating was performed on sample.

    table2.csv
    Modal mineralogy of gneisses. Values are visual estimates of percentages from petrographic analysis. (Source: Garth Graham)

    Sample
    Items in the Sample field. (Source: Garth Graham)

    A unique sample identifier

    UTMX
    Easting for UTM Zone 6, NAD 27 (Source: Garth Graham)

    Range of values
    Minimum:525000
    Maximum:542000
    Units:meters

    UTMY
    Northing for UTM Zone 6, NAD 27 (Source: Garth Graham)

    Range of values
    Minimum:7133090
    Maximum:7195200
    Units:meters

    Quartz
    Quartz (Source: Garth Graham)

    Range of values
    Minimum:0
    Maximum:100
    Units:percent

    Plag
    Plagioclase (Source: Garth Graham)

    Range of values
    Minimum:0
    Maximum:100
    Units:percent

    Kspar
    Potassium feldspar (Source: Garth Graham)

    Range of values
    Minimum:0
    Maximum:100
    Units:percent

    Biot
    Biotite (Source: Garth Graham)

    Range of values
    Minimum:0
    Maximum:100
    Units:percent

    Opaques
    Opaque minerals (Source: Garth Graham)

    Range of values
    Minimum:0
    Maximum:100
    Units:percent

    Sill
    Sillimanite (Source: Garth Graham)

    Range of values
    Minimum:0
    Maximum:100
    Units:percent

    Gar
    Garnet (Source: Garth Graham)

    Range of values
    Minimum:0
    Maximum:100
    Units:percent

    Chl
    Chlorite (Source: Garth Graham)

    Range of values
    Minimum:0
    Maximum:100
    Units:percent

    table3.csv
    Estimated modal mineral abundances (volume %) in felsic dike thin sections. (Source: Garth Graham)

    Sample
    Items in the Sample field. (Source: Garth Graham)

    A unique sample identifier

    Group
    A suite of rocks that are similar in their mineralogy. The rocks were grouped based on having a molecular proportion of aluminum oxide greater than that of sodium oxide and potassium oxide combined. (Source: Garth Graham)

    ValueDefinition
    1strongly peraluminous magmatic suite of rocks
    2Weakly- to non-peraluminous magmatic suite of rocks

    Qtz
    Estimated modal mineral abundance of quartz (volume %) in felsic dike thin section. (Source: Garth Graham)

    Range of values
    Minimum:0
    Maximum:100
    Units:percent volume

    Plag
    Estimated modal mineral abundance of plagioclase (volume %) in felsic dike thin section. (Source: Garth Graham)

    Range of values
    Minimum:0
    Maximum:100
    Units:percent volume

    Kspar
    Estimated modal mineral abundance of potassium feldspar (volume %) in felsic dike thin section. (Source: Garth Graham)

    Range of values
    Minimum:0
    Maximum:100
    Units:percent volume

    Tourm
    Estimated modal mineral abundance of tourmaline (volume %) in felsic dike thin section. (Source: Garth Graham)

    Range of values
    Minimum:0
    Maximum:100
    Units:percent volume

    Mica
    Estimated modal mineral abundance of white mica and minor biotite (volume %) in felsic dike thin section. (Source: Garth Graham)

    Range of values
    Minimum:0
    Maximum:100
    Units:percent volume

    Point Cnts.
    Point counts: number of points counted (Source: Garth Graham)

    Range of values
    Minimum:0
    Maximum:109
    Units:point counts

    table4.csv
    XRF major oxide and normative values for gneiss samples in the Richardson study area. (Source: Garth Graham)

    Sample
    Items in the Sample field. (Source: Garth Graham)

    A unique sample identifier

    SiO2
    Silicon dioxide values acquired by analysis with X-ray Fluorescence (XRF) and shown in percent (%). (Source: Bondar-Clegg)

    Range of values
    Minimum:0.01
    Maximum:100
    Units:percent

    TiO2
    Titanium oxide values acquired by analysis with X-ray Fluorescence (XRF) and shown in percent (%). (Source: Bondar-Clegg)

    Range of values
    Minimum:0.01
    Maximum:100
    Units:percent

    Al2O3
    Aluminum oxide values acquired by analysis with X-ray Fluorescence (XRF) and shown in percent (%). (Source: Bondar-Clegg)

    Range of values
    Minimum:0.01
    Maximum:100
    Units:percent

    Fe2O3
    Iron oxide (+3) values acquired by analysis with X-ray Fluorescence (XRF) and shown in percent (%). (Source: Bondar-Clegg)

    Range of values
    Minimum:0.01
    Maximum:100
    Units:percent

    MnO
    Manganese oxide values acquired by analysis with X-ray Fluorescence (XRF) and shown in percent (%). (Source: Bondar-Clegg)

    Range of values
    Minimum:0.01
    Maximum:100
    Units:percent

    MgO
    Magnesium oxide values acquired by analysis with X-ray Fluorescence (XRF) and shown in percent (%). (Source: Bondar-Clegg)

    Range of values
    Minimum:0.01
    Maximum:100
    Units:percent

    CaO
    Calcium oxide values acquired by analysis with X-ray Fluorescence (XRF) and shown in percent (%). (Source: Bondar-Clegg)

    Range of values
    Minimum:0.01
    Maximum:100
    Units:percent

    Na2O
    Sodium oxide values acquired by analysis with X-ray Fluorescence (XRF) and shown in percent (%). (Source: Bondar-Clegg)

    Range of values
    Minimum:0.01
    Maximum:100
    Units:percent

    K2O
    Potassium oxide values acquired by analysis with X-ray Fluorescence (XRF) and shown in percent (%). (Source: Bondar-Clegg)

    Range of values
    Minimum:0.01
    Maximum:100
    Units:percent

    P2O5
    Phosphorus pentoxide values acquired by analysis with X-ray Fluorescence (XRF) and shown in percent (%). (Source: Bondar-Clegg)

    Range of values
    Minimum:0.01
    Maximum:100
    Units:percent

    LOI
    Loss on Ignition (LOI) values shown in percent. (Source: Bondar-Clegg)

    Range of values
    Minimum:0.01
    Maximum:100
    Units:percent

    Total
    Calculated oxide and LOI total for sample shown in percent. (Source: Bondar-Clegg)

    Range of values
    Minimum:0.01
    Maximum:105
    Units:percent

    %AN
    (Normative Anorthite/Normative Anorthite + Normative Albite) *100 (Source: Rainer Newberry)

    Range of values
    Minimum:0
    Maximum:100
    Units:percent

    Q
    CIPW Norm quartz calculation (Source: Garth Graham)

    Range of values
    Minimum:0
    Maximum:100
    Units:percent

    or
    CIPW norm orthoclase calculation (Source: Garth Graham)

    Range of values
    Minimum:0
    Maximum:100
    Units:percent

    ab
    CIPW norm albite calculation (Source: Garth Graham)

    Range of values
    Minimum:0
    Maximum:100
    Units:percent

    an
    CIPW norm anorthite calculation (Source: Garth Graham)

    Range of values
    Minimum:0
    Maximum:100
    Units:percent

    C
    CIPW norm corundum calculation (Source: Garth Graham)

    Range of values
    Minimum:0
    Maximum:100
    Units:percent

    hy
    CIPW norm hypersthene calculation (Source: Garth Graham)

    Range of values
    Minimum:0
    Maximum:100
    Units:percent

    mt
    CIPW norm magnetite calculation (Source: Garth Graham)

    Range of values
    Minimum:0
    Maximum:100
    Units:percent

    il
    CIPW norm ilmenite calculation (Source: Garth Graham)

    Range of values
    Minimum:0
    Maximum:100
    Units:percent

    hem
    CIPW norm hematite calculation (Source: Garth Graham)

    Range of values
    Minimum:0
    Maximum:100
    Units:percent

    ap
    CIPW norm apatite calculation (Source: Garth Graham)

    Range of values
    Minimum:0
    Maximum:100
    Units:percent

    table5.csv
    XRF major and minor element results for amphibolite samples 127 and 158B. (Source: Garth Graham)

    Sample
    Items in the Samples field. (Source: Garth Graham)

    A unique sample identifier

    SiO2
    Silicon dioxide values acquired by analysis with X-ray Fluorescence (XRF) and shown in percent (%). (Source: Bondar-Clegg)

    Range of values
    Minimum:0.01
    Maximum:100
    Units:percent

    TiO2
    Titanium oxide values acquired by analysis with X-ray Fluorescence (XRF) and shown in percent (%). (Source: Bondar-Clegg)

    Range of values
    Minimum:0.01
    Maximum:100
    Units:percent

    Al2O3
    Aluminum oxide values acquired by analysis with X-ray Fluorescence (XRF) and shown in percent (%). (Source: Bondar-Clegg)

    Range of values
    Minimum:0.01
    Maximum:100
    Units:percent

    Fe2O3
    Iron oxide (+3) values acquired by analysis with X-ray Fluorescence (XRF) and shown in percent (%). (Source: Bondar-Clegg)

    Range of values
    Minimum:0.01
    Maximum:100
    Units:percent

    MnO
    Manganese oxide values acquired by analysis with X-ray Fluorescence (XRF) and shown in percent (%). (Source: Bondar-Clegg)

    Range of values
    Minimum:0.01
    Maximum:100
    Units:percent

    MgO
    Magnesium oxide values acquired by analysis with X-ray Fluorescence (XRF) and shown in percent (%). (Source: Bondar-Clegg)

    Range of values
    Minimum:0.01
    Maximum:100
    Units:percent

    CaO
    Calcium oxide values acquired by analysis with X-ray Fluorescence (XRF) and shown in percent (%). (Source: Bondar-Clegg)

    Range of values
    Minimum:0.01
    Maximum:100
    Units:percent

    Na2O
    Sodium oxide values acquired by analysis with X-ray Fluorescence (XRF) and shown in percent (%). (Source: Bondar-Clegg)

    Range of values
    Minimum:0.01
    Maximum:100
    Units:percent

    K2O
    Potassium oxide values acquired by analysis with X-ray Fluorescence (XRF) and shown in percent (%). (Source: Bondar-Clegg)

    Range of values
    Minimum:0.01
    Maximum:100
    Units:percent

    P2O5
    Phosphorus pentoxide values acquired by analysis with X-ray Fluorescence (XRF) and shown in percent (%). (Source: Bondar-Clegg)

    Range of values
    Minimum:0.01
    Maximum:100
    Units:percent

    LOI
    Loss on Ignition (LOI) values shown in percent. (Source: Bondar-Clegg)

    Range of values
    Minimum:0.01
    Maximum:100
    Units:percent

    Total
    Calculated oxide and LOI total for sample shown in percent. (Source: Bondar-Clegg)

    Range of values
    Minimum:0.01
    Maximum:105
    Units:percent

    Ba
    Barium values acquired by analysis with X-ray Fluorescence (XRF) and shown in parts per million (ppm). (Source: Garth Graham)

    Range of values
    Minimum:0
    Maximum:100000
    Units:ppm

    Sr
    Strontium values acquired by analysis with X-ray Fluorescence (XRF) and shown in parts per million (ppm). (Source: Garth Graham)

    Range of values
    Minimum:0
    Maximum:100000
    Units:ppm

    Y
    Yttrium values acquired by analysis with X-ray Fluorescence (XRF) and shown in parts per million (ppm). (Source: Garth Graham)

    Range of values
    Minimum:0
    Maximum:100000
    Units:ppm

    Nb
    Niobium values acquired by analysis with X-ray Fluorescence (XRF) and shown in parts per million (ppm). (Source: Garth Graham)

    Range of values
    Minimum:0
    Maximum:100000
    Units:ppm

    Zr
    Zirconium values acquired by analysis with X-ray Fluorescence (XRF) and shown in parts per million (ppm). (Source: Garth Graham)

    Range of values
    Minimum:0
    Maximum:100000
    Units:ppm

    Rb
    Rubidium values acquired by analysis with X-ray Fluorescence (XRF) and shown in parts per million (ppm). (Source: Garth Graham)

    Range of values
    Minimum:0
    Maximum:100000
    Units:ppm

    table6.csv
    XRF major oxide and normative values for igneous rock samples in the Richardson study area. (Source: Garth Graham)

    Sample
    Items in the Sample field. (Source: Garth Graham)

    A unique sample identifier

    Rock type
    Description of rock (Source: Garth Graham)

    Description of rock type

    SiO2
    Silicon dioxide values acquired by analysis with X-ray Fluorescence (XRF) and shown in percent (%). (Source: Bondar-Clegg)

    Range of values
    Minimum:0.01
    Maximum:100
    Units:percent

    TiO2
    Titanium oxide values acquired by analysis with X-ray Fluorescence (XRF) and shown in percent (%). (Source: Bondar-Clegg)

    Range of values
    Minimum:0.01
    Maximum:100
    Units:percent

    Al2O3
    Aluminum oxide values acquired by analysis with X-ray Fluorescence (XRF) and shown in percent (%). (Source: Bondar-Clegg)

    Range of values
    Minimum:0.01
    Maximum:100
    Units:percent

    Fe2O3
    Iron oxide (+3) values acquired by analysis with X-ray Fluorescence (XRF) and shown in percent (%). (Source: Bondar-Clegg)

    Range of values
    Minimum:0.01
    Maximum:100
    Units:percent

    MnO
    Manganese oxide values acquired by analysis with X-ray Fluorescence (XRF) and shown in percent (%). (Source: Bondar-Clegg)

    Range of values
    Minimum:0.01
    Maximum:100
    Units:percent

    MgO
    Magnesium oxide values acquired by analysis with X-ray Fluorescence (XRF) and shown in percent (%). (Source: Bondar-Clegg)

    Range of values
    Minimum:0.01
    Maximum:100
    Units:percent

    CaO
    Calcium oxide values acquired by analysis with X-ray Fluorescence (XRF) and shown in percent (%). (Source: Bondar-Clegg)

    Range of values
    Minimum:0.01
    Maximum:100
    Units:percent

    Na2O
    Sodium oxide values acquired by analysis with X-ray Fluorescence (XRF) and shown in percent (%). (Source: Bondar-Clegg)

    Range of values
    Minimum:0.01
    Maximum:100
    Units:percent

    K2O
    Potassium oxide values acquired by analysis with X-ray Fluorescence (XRF) and shown in percent (%). (Source: Bondar-Clegg)

    Range of values
    Minimum:0.01
    Maximum:100
    Units:percent

    P2O5
    Phosphorus pentoxide values acquired by analysis with X-ray Fluorescence (XRF) and shown in percent (%). (Source: Bondar-Clegg)

    Range of values
    Minimum:0.01
    Maximum:100
    Units:percent

    LOI
    Loss on Ignition (LOI) values shown in percent. (Source: Bondar-Clegg)

    Range of values
    Minimum:0.01
    Maximum:100
    Units:percent

    Total
    Calculated oxide and LOI total for sample shown in percent. (Source: Bondar-Clegg)

    Range of values
    Minimum:0.01
    Maximum:105
    Units:percent

    %AN
    (Normative Anorthite/Normative Anorthite + Normative Albite) *100 (Source: Rainer Newberry)

    Range of values
    Minimum:0
    Maximum:100
    Units:percent

    Q
    CIPW Norm quartz calculation (Source: Garth Graham)

    Range of values
    Minimum:0
    Maximum:100
    Units:percent

    or
    CIPW norm orthoclase calculation (Source: Garth Graham)

    Range of values
    Minimum:0
    Maximum:100
    Units:percent

    ab
    CIPW norm albite calculation (Source: Garth Graham)

    Range of values
    Minimum:0
    Maximum:100
    Units:percent

    an
    CIPW norm anorthite calculation (Source: Garth Graham)

    Range of values
    Minimum:0
    Maximum:100
    Units:percent

    C
    CIPW norm corundum calculation (Source: Garth Graham)

    Range of values
    Minimum:0
    Maximum:100
    Units:percent

    hy
    CIPW norm hypersthene calculation (Source: Garth Graham)

    Range of values
    Minimum:0
    Maximum:100
    Units:percent

    mt
    CIPW norm magnetite calculation (Source: Garth Graham)

    Range of values
    Minimum:0
    Maximum:100
    Units:percent

    il
    CIPW norm ilmenite calculation (Source: Garth Graham)

    Range of values
    Minimum:0
    Maximum:100
    Units:percent

    hem
    CIPW norm hematite calculation (Source: Garth Graham)

    Range of values
    Minimum:0
    Maximum:100
    Units:percent

    ap
    CIPW norm apatite calculation (Source: Garth Graham)

    Range of values
    Minimum:0
    Maximum:100
    Units:percent

    ru
    CIPW norm rutile calculation (Source: Garth Graham)

    Range of values
    Minimum:0
    Maximum:100
    Units:percent volume

    table7.csv
    Trace element compositions (in ppm) of igneous rocks from the Richardson study area. (Source: Garth Graham)

    Sample
    Items in the Sample field. (Source: Garth Graham)

    A unique sample identifier

    Unit
    Name of a structural feature with a distinctive appearance. (Source: Garth Graham)

    Name of a structural feature with a distinctive appearance.

    Ba
    Barium values acquired by analysis with X-ray Fluorescence (XRF) and shown in parts per million (ppm). (Source: Garth Graham)

    Range of values
    Minimum:0
    Maximum:100000
    Units:ppm

    Nb
    Niobium values acquired by analysis with X-ray Fluorescence (XRF) and shown in parts per million (ppm). (Source: Garth Graham)

    Range of values
    Minimum:0
    Maximum:100000
    Units:ppm

    Rb
    Rubidium values acquired by analysis with X-ray Fluorescence (XRF) and shown in parts per million (ppm). (Source: Garth Graham)

    Range of values
    Minimum:0
    Maximum:100000
    Units:ppm

    Sr
    Strontium values acquired by analysis with X-ray Fluorescence (XRF) and shown in parts per million (ppm). (Source: Garth Graham)

    Range of values
    Minimum:0
    Maximum:100000
    Units:ppm

    Y
    Yttrium values acquired by analysis with X-ray Fluorescence (XRF) and shown in parts per million (ppm). (Source: Garth Graham)

    Range of values
    Minimum:0
    Maximum:100000
    Units:ppm

    Zr
    Zirconium values acquired by analysis with X-ray Fluorescence (XRF) and shown in parts per million (ppm). (Source: Garth Graham)

    Range of values
    Minimum:0
    Maximum:100000
    Units:ppm

    Nb+Y
    Total of Niobium and Yttrium (Source: Garth Graham)

    Range of values
    Minimum:0
    Maximum:100000
    Units:ppm

    table8.csv
    Samples employed for Geothermometry and Geobarometry from Richardson field area. (Source: Garth Graham)

    Sample
    Items in the Sample field. (Source: Garth Graham)

    A unique sample identifier

    UTM N
    Northing for UTM Zone 6, NAD 27 (Source: Garth Graham)

    Range of values
    Minimum:7133090
    Maximum:7195200
    Units:meters

    UTM E
    Easting for UTM Zone 6, NAD 27 (Source: Garth Graham)

    Range of values
    Minimum:525000
    Maximum:542000
    Units:meters

    Fault block
    Direction of fault block (Source: Garth Graham)

    ValueDefinition
    NENortheast
    EEast
    WWest
    SSouth
    NWNorthwest

    Mineral assemblage present
    Minerals present in rock sample. (Source: Garth Graham)

    Quartz-plagioclase-biotite-muscovite-sillimanite-garnet

    Quartz-plagioclase-biotite-sillimanite-garnet

    Quartz-plagioclase-biotite-garnet

    Quartz-plagioclase-biotite-sillimanite-garnet

    Quartz-plagioclase-biotite-garnet

    Geobarometer(s) employed
    Mineral assemblages used in determining sample temperature and pressure conditions. (Source: Garth Graham)

    ValueDefinition
    1garnet-sillimanite-plagioclase-quartz
    2garnet-muscovite-plagioclase-biotite
    3garnet-muscovite-plagioclase-quartz
    4garnet-muscovite-sillimanite-quartz
    5garnet-muscovite-biotite-sillimanite

    Temp Est. (degree C)
    Calculated temperature experienced by metamorphic rocks in the Richardson area. (Source: Garth Graham)

    Range of values
    Minimum:450
    Maximum:725
    Units:degree Celsius

    table9.csv
    Average microprobe data of mineral assemblages for geothermobarometric calculations. (Source: Garth Graham)

    Sample
    Items in the Sample field. (Source: Garth Graham)

    A unique sample identifier

    Mineral
    Mineral analyzed by microprobe. (Source: Garth Graham)

    ValueDefinition
    ggarnet
    bbiotite
    hhornblende
    wmwhite mica
    pplagioclase

    Na2O
    Sodium oxide average values acquired by analysis with microprobe and shown in percent (%). (Source: Garth Graham)

    Range of values
    Minimum:0.01
    Maximum:100
    Units:percent

    MgO
    Magnesium oxide average values acquired by analysis with microprobe and shown in percent (%). (Source: Garth Graham)

    Range of values
    Minimum:0.01
    Maximum:100
    Units:percent

    Al2O3
    Aluminum oxide average values acquired by analysis with microprobe and shown in percent (%). (Source: Garth Graham)

    Range of values
    Minimum:0.01
    Maximum:100
    Units:percent

    SiO2
    Silicon dioxide average values acquired by analysis with microprobe and shown in percent (%). (Source: Garth Graham)

    Range of values
    Minimum:0.01
    Maximum:100
    Units:percent

    K2O
    Potassium oxide average values acquired by analysis with microprobe and shown in percent (%). (Source: Garth Graham)

    Range of values
    Minimum:0.01
    Maximum:100
    Units:percent

    CaO
    Calcium oxide average values acquired by analysis with microprobe and shown in percent (%). (Source: Garth Graham)

    Range of values
    Minimum:0.01
    Maximum:100
    Units:percent

    TiO2
    Titanium dioxide average values acquired by analysis with microprobe and shown in percent (%). (Source: Garth Graham)

    Range of values
    Minimum:0.01
    Maximum:100
    Units:percent

    FeO
    Iron oxide (+2) average values acquired by analysis with microprobe and shown in percent (%). (Source: Garth Graham)

    Range of values
    Minimum:0.01
    Maximum:100
    Units:percent

    MnO
    Manganese oxide average values acquired by analysis with microprobe and shown in percent (%). (Source: Garth Graham)

    Range of values
    Minimum:0.01
    Maximum:100
    Units:percent

    H2Oc
    Calculated water content in percent (%). (Source: Garth Graham)

    Range of values
    Minimum:0.01
    Maximum:100
    Units:percent

    Total
    Total of major and minor oxides and water in percent (%). (Source: Garth Graham)

    Range of values
    Minimum:0.01
    Maximum:105
    Units:percent

    Na
    Sodium cations per formula unit. (Source: Garth Graham)

    Standard recalculation of compositions. See W.A. Deer, R.A. Howie, J. Zussman (1992). An introduction to the rock-forming minerals, 2nd ed.. Longman Scientific & Technical, Harlow for more information.

    Mg
    Magnesium cations per formula unit. (Source: Garth Graham)

    Standard recalculation of compositions. See W.A. Deer, R.A. Howie, J. Zussman (1992). An introduction to the rock-forming minerals, 2nd ed.. Longman Scientific & Technical, Harlow for more information.

    Al
    Aluminum cations per formula unit. (Source: Garth Graham)

    Standard recalculation of compositions. See W.A. Deer, R.A. Howie, J. Zussman (1992). An introduction to the rock-forming minerals, 2nd ed.. Longman Scientific & Technical, Harlow for more information.

    Si
    Silicon cations per formula unit. (Source: Garth Graham)

    Standard recalculation of compositions. See W.A. Deer, R.A. Howie, J. Zussman (1992). An introduction to the rock-forming minerals, 2nd ed.. Longman Scientific & Technical, Harlow for more information.

    K
    Potassium cations per formula unit. (Source: Garth Graham)

    Standard recalculation of compositions. See W.A. Deer, R.A. Howie, J. Zussman (1992). An introduction to the rock-forming minerals, 2nd ed.. Longman Scientific & Technical, Harlow for more information.

    Ca
    Calcium cations per formula unit. (Source: Garth Graham)

    Standard recalculation of compositions. See W.A. Deer, R.A. Howie, J. Zussman (1992). An introduction to the rock-forming minerals, 2nd ed.. Longman Scientific & Technical, Harlow for more information.

    Ti
    Titanium cations per formula unit. (Source: Garth Graham)

    Standard recalculation of compositions. See W.A. Deer, R.A. Howie, J. Zussman (1992). An introduction to the rock-forming minerals, 2nd ed.. Longman Scientific & Technical, Harlow for more information.

    Fe
    Iron cations per formula unit. (Source: Garth Graham)

    Standard recalculation of compositions. See W.A. Deer, R.A. Howie, J. Zussman (1992). An introduction to the rock-forming minerals, 2nd ed.. Longman Scientific & Technical, Harlow for more information.

    Mn
    Manganese cations per formula unit. (Source: Garth Graham)

    Standard recalculation of compositions. See W.A. Deer, R.A. Howie, J. Zussman (1992). An introduction to the rock-forming minerals, 2nd ed.. Longman Scientific & Technical, Harlow for more information.

    Ca site tot
    Number of cations in site containing calcium. (Source: Garth Graham)

    Standard recalculation of compositions. See W.A. Deer, R.A. Howie, J. Zussman (1992). An introduction to the rock-forming minerals, 2nd ed.. Longman Scientific & Technical, Harlow for more information.

    O
    Total oxygen cations per formula unit. (Source: Garth Graham)

    Standard recalculation of compositions. See W.A. Deer, R.A. Howie, J. Zussman (1992). An introduction to the rock-forming minerals, 2nd ed.. Longman Scientific & Technical, Harlow for more information.

    Fe/Mg
    Number of iron cations divided by the number of magnesium cations. (Source: Garth Graham)

    Standard recalculation of compositions. See W.A. Deer, R.A. Howie, J. Zussman (1992). An introduction to the rock-forming minerals, 2nd ed.. Longman Scientific & Technical, Harlow for more information.

    %An
    The mole percent anorthite component in plagioclase. (Source: Garth Graham, Jessica F. Larsen)

    Range of values
    Minimum:0
    Maximum:100
    Units:percent

    -lnKb-g
    Negative log of (Fe/Mg cations (biotite) - Fe/Mg cations (garnet)). (Source: Garth Graham)

    Standard calculation. See W.A. Deer, R.A. Howie, J. Zussman (1992). An introduction to the rock-forming minerals, 2nd ed.. Longman Scientific & Technical, Harlow for more information.

    avg T,P
    Average temperature in degrees C and average pressure in kilobars. (Source: Garth Graham)

    Calculated temperature and pressure using several models: Perchuk and Lavrenteva, 1984; Kleemann and Reinhardt, 1994; and Berman, 1990.

    table10.csv
    Fluid inclusion samples, locations, and assay values of sampled interval. (Source: Garth Graham)

    Slide (JGA-)
    Slide identification number starting with JGA- (Source: Garth Graham)

    A unique sample identifier

    site
    Sample location (Source: Garth Graham)

    A unique sample identifier

    UTM E
    Easting for UTM Zone 6, NAD 27 (Source: Garth Graham)

    Range of values
    Minimum:525000
    Maximum:542000
    Units:meters

    UTM N
    Northing for UTM Zone 6, NAD 27 (Source: Garth Graham)

    Range of values
    Minimum:7133090
    Maximum:7195200
    Units:meters

    Au Assay value (ppm)
    Gold assay value in parts per million (ppm). (Source: Garth Graham)

    Range of values
    Minimum:0
    Maximum:53
    Units:part per million

    Gold Group
    Sample classification based on the gold assay value of the entire interval containing the quartz vein. (Source: Garth Graham)

    ValueDefinition
    4high grade gold
    3significant gold interval
    2gold-bearing interval
    1gold below detection level

    table11.csv
    Fluid inclusion data and estimated fluid parameters. (Source: Garth Graham)

    Hole
    Number of the inclusion hole analyzed (Source: Garth Graham)

    A unique sample identifier

    Slide
    Number of the sample slide analyzed. (Source: Garth Graham)

    ValueDefinition
    1Sample BK1-035 in Table 9
    2Sample BK1-65 in table 9
    4Sample BK1-082 in Table 9
    11Sample BK2-047 (AuVn) in table 9
    12Sample BK2-012 in table 9.
    13Sample BK2-135 in Table 9.
    15Sample BK2-152(s15) in Table 9.
    BuckeyeSample B3 (Buckeye Discovery) in Table 9.

    Inclusion
    Number of the inclusion analyzed. (Source: Garth Graham)

    Number in field depends on how many inclusions where able to be ultimately analyzed.

    CO2
    Melting temperature of carbon dioxide in degree Celsius. (Source: Garth Graham)

    Averaged melting temperature base on number of inclusions analyzed.

    Clath
    Clathrate melting temperature in degree Celsius. (Source: Garth Graham)

    Average clathrate melting of analyzed inclusions.

    Cohom
    Partial homogenization of carbonic phase in degree Celsius. (Source: Garth Graham)

    Average cohomogenization temperature of carbonic phase.

    Homog
    Total homogenization of carbonic pase in degree Celsius. (Source: Garth Graham)

    Average total homogenization temperature for carbonic phase.

    Au group
    Sample classification based on the gold assay value of the entire interval containing the quartz vein. (Source: Garth Graham)

    ValueDefinition
    3significant gold interval
    2gold-bearing interval
    1gold below detection level

    Volume
    Volume of vapor within inclusion shown in percent. (Source: Garth Graham)

    Range of values
    Minimum:0
    Maximum:100
    Units:percent

    Bars
    Fluid inclusion pressure in bars after Angus and others, 1976. (Source: Garth Graham)

    Fluid inclusion pressure in bars.

    Density
    CO2 density of the inclusion after Burress, 1981. (Source: Garth Graham)

    Calculation of CO2 density.

    MoleH2O
    Calculated mole percent of H2O in inclusion fluids. (Source: Garth Graham)

    Range of values
    Minimum:0
    Maximum:100
    Units:percent

    Est. Press
    Estimated minimum pressure at time of inclusion formation in bars. Employed P-T density isochores from Kennedy, 1954 and diagrams from Brown and Lamb, 1989. (Source: Garth Graham)

    Estimated pressure at time of inclusion formation.

    table12.csv
    Comparison between Bald Knob, Democrat, Ryan Lode fluid inclusion data. (Source: Garth Graham)

    Sample
    Unique sample identifier (Source: Garth Graham)

    ValueDefinition
    Demo 1Democrat lode deposit
    Demo 2Democrat lode sample
    BKhiPBald Knob high pressure sample type
    BKloPBald Knob low pressure sample.
    Ryan LodeRyan lode deposit, Fairbanks district.
    BKeye1Buckeye high grade vein.
    Bkeye2Buckeye high grade vein.

    Size (micron)
    Size range of inclusions in microns (Source: Garth Graham)

    Size range of inclusions.

    TmCO2 (degree C)
    Final melting temperature of solid CO2 in degree Celsius. (Source: Garth Graham)

    Range of final melting temperatures of solid CO2.

    Clathrate T. (degree C)
    Final clathrate melting temperature range in degree Celsius. (Source: Garth Graham)

    Range of final melting temperatures of solid CO2.

    Th (degree C)
    Temperature range of total homogenization of carbonic phase in degree Celsius. (Source: Garth Graham)

    Temperature range of total homogenization of carbonic phase.

    Volume % vapor
    Estimated percentage of total in inclusion of vapor. (Source: Garth Graham)

    Range of estimated percentages of vapor in inclusion.

    Salinity (% NaCl)
    Salinity of fluid expressed as weight percent (%) NaCl equivalent. (Source: Garth Graham)

    Range of values in percent or "Low" value of NaCl in fluid.

    Mol % CO2
    Molar percent of CO2 in inclusion. (Source: Garth Graham)

    Value, range, average, variable or unknown molar percent of CO2 in inclusions.

    Trap P (bars)
    Estimated pressure in bars at time of formation of inclusions. (Source: Garth Graham)

    Range or "unknown" value of pressure of inclusions at time of formation.

    table13.csv
    Interpreted 40Ar/39Ar ages (in Ma) for Richardson area samples. (Source: Garth Graham)

    Sample number (mineral)
    Unique sample identifier and mineral analyzed in sample. (Source: Garth Graham)

    ValueDefinition
    Bbiotite
    WMwhite mica

    Unique sample identifier

    Low-temp fraction(s) age (%Ar)
    Apparent ages yielded from heating at low temperature in millions of years (Ma). %Ar equals total 39Ar released in the fraction(s). (Source: Garth Graham)

    Age dates +/- standard error

    Percent total 39Ar released in fractions.

    High-temp fraction(s) age (%Ar)
    Apparent ages yielded from heating at high temperature in millions of years (Ma). %Ar equals percent total 39Ar released in the fraction(s). (Source: Garth Graham)

    Age dates +/- standard error

    Percent total 39Ar released in fractions.

    Plateau age (%Ar)
    Plateau age is a measure of the time elapsed since the mineral cooled to below its closure temperature. Age is in millions of years (Ma). %Ar equals percent total 39Ar released in the fraction(s). (Source: Garth Graham)

    Age dates +/- standard error

    Percent total 39Ar released in fractions.

    Interpreted age
    Weighted average of all the Ar fractions released and is equivalent to a conventional K-Ar age. (Source: Garth Graham)

    Estimated age/age range in millions of years with standard error.

    table14.csv
    Ages of geologic events in the Richardson area as suggested by radiometric dating. (Source: Garth Graham)

    Event
    Geologic event that occurred at interpreted age. (Source: Garth Graham)

    Geological event description.

    Interpreted Age
    Approximate interpreted age in Ma of event. (Source: Garth Graham)

    Approximate age in Ma of event.

    Evidence
    Geological evidence for interpreted age of event. (Source: Garth Graham)

    Description of evidence for interpreted age of event.

    table15.csv
    40Ar/39Ar step-heating results and data. (Source: Garth Graham)

    Laser Power
    Laser power in milliwatts. (Source: Garth Graham)

    Range of values
    Minimum:0
    Maximum:8800
    Units:mW

    Fraction 39Ar
    The fraction of 39Ar released in each step of a run. (Source: Garth Graham)

    Range of values
    Minimum:0
    Maximum:1

    +/-
    1-sigma error (Source: Garth Graham)

    1-sigma error unitless.

    37Ar/39Ar measured
    Ratio of 37Ar to 39Ar. Measured isotopic ratios are corrected for reactor induced interferences and decay of 37Ar and 39Ar. (Source: Garth Graham)

    Unitless ratio.

    +/-
    1-sigma error (Source: Garth Graham)

    1-sigma error unitless.

    36Ar/39Ar measured
    Ratio of 36Ar to 39Ar. Measured isotopic ratios are corrected for reactor induced interferences and decay of 37Ar and 39Ar. (Source: Garth Graham)

    Unitless ratio.

    +/-
    1-sigma error. (Source: Garth Graham)

    1-sigma error unitless.

    % Atm. 40Ar*
    Percent of atmospheric 40Ar in the sample assuming an initial 40Ar/36Ar ratio of 295.5. Results include error. (Source: Garth Graham)

    Range of values
    Minimum:0
    Maximum:100
    Units:percent

    Ca/K
    ratio of calcium to potassium (Source: Garth Graham)

    Unitless ratio.

    Cl/K
    Ratio of chlorine to potassium. (Source: Garth Graham)

    Unitless ratio.

    40*/39K
    The ratio of radiogenic 40Ar to 39Ar produced from potassium calculated using the equations and constants quoted in McDougall and Harrison (1988). (Source: Paul Layer, Garth Graham)

    Unitless ratio.

    Age (Ma)
    Ages calculated from 40A*/39K using the equations and constants quoted in McDougall and Harrison (1988). (Source: Garth Graham)

    Range of values
    Minimum:0
    Maximum:4200
    Units:Ma

    +/- (Ma)
    1-sigma error in Ma. (Source: Garth Graham)

    Range of values
    Minimum:0
    Maximum:4200
    Units:Ma


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?


Why was the data set created?

The objective of the project was to create a more accurate geologic map of a portion of the Richardson district and to propose a model for the geological evolution of the Richardson area.


How was the data set created?

  1. From what previous works were the data drawn?

    Ruperto and others, 1964 (source 1 of 11)
    Ruperto, V.L., Stevens, R.E., and Norman, M.B., 1964, Staining of plagioclase feldspars and other minerals with F.D. and C. Red No. 2: U.S. Geological Survey Professional Paper PP 501-B.

    Other_Citation_Details: p. B152-B153
    Type_of_Source_Media: paper
    Source_Contribution:
    36 metamorphic and 4 igneous hand specimens were etched and stained for quartz, plagioclase, and K-feldspar using the technique of Ruperto, V.L., Stevens, R.E., and Norman, M.B., 1964.

    Spear and Kohn, 1999 (source 2 of 11)
    Spear, F.S., and Kohn, M.J., 199905, Thermobarometry (GTB), Version 2.1.

    Type_of_Source_Media: computer program
    Source_Contribution:
    Microprobe data collected on biotite, garnet, white mica and K-feldspar were processed using the Macintosh Geothermobarometry program GTB.

    Perchuk and Lavrenteva, 1983 (source 3 of 11)
    Perchuk, L.L., and Lavrenteva, I.V., 1983, Experimental investigation of exchange equilibria in the system cordierite-garnet-biotite, in Saxena, S.K.: Springer Verlag, New York.

    Other_Citation_Details:
    in Saxena, S.K., ed., Kinetics and Equilibrium in Mineral Reactions, p. 199-240
    This is part of the following larger work.

    Saxena, S.K.(ed.), 1983, Kinetics and equilibrium in mineral reactions: Springer-Verlag, New York.

    Type_of_Source_Media: paper
    Source_Contribution:
    One of several garnet-biotite distribution models which were used for biotite-garnet thermometry comparisons.

    Kleeman and Reinhardt, 1994 (source 4 of 11)
    Kleeman, U., and Reinhardt, J., 1994, Garnet-biotite thermometry revisited: The effect of Al VI and Ti in biotite: European Journal of Mineralogy v. 6.

    Other_Citation_Details: p. 925-941
    Type_of_Source_Media: paper
    Source_Contribution:
    One of several garnet-biotite distribution models which were used for biotite-garnet thermometry comparisons.

    Berman, 1990 (source 5 of 11)
    Berman, R.G., 1990, Mixing properties of Ca-Mg-Fe-Mn garnets: American Mineralogist v. 75.

    Other_Citation_Details: p. 328-334
    Type_of_Source_Media: paper
    Source_Contribution:
    One of several garnet-biotite distribution models which were used for biotite-garnet thermometry comparisons.

    Holdaway, 1971 (source 6 of 11)
    Holdaway, M.J., 1971, Stability of andalusite and the aluminum silicate phase diagram: American Journal of Science v. 271.

    Other_Citation_Details: p. 97-131
    Type_of_Source_Media: paper
    Source_Contribution:
    Pressures were estimated based on the aluminosilicate stability diagram of Holdaway.

    Spear, 1993 (source 7 of 11)
    Spear, F.S., 1993, Metamorphic phase equilibria and pressure-temperature-time paths: Mineralogical Society of America, Washington, D.C..

    Other_Citation_Details: 799 p.
    Type_of_Source_Media: paper
    Source_Contribution:
    Pressures were estimated based on several compositional-based geobarometers of Spear.

    Douglas, 1996 (source 8 of 11)
    Douglas, T.A., 1996, Metamorphic histories of the Chatanika eclogite and Fairbanks schist within the Yukon-Tanana terrane, Alaska as revealed by electron microprobe thermobarometry and 40Ar/39Ar single grain dating: University of Alaska, Fairbanks, University of Alaska, Fairbanks.

    Other_Citation_Details: 240 p.
    Type_of_Source_Media: paper
    Source_Contribution:
    Five samples were dated using the 40Ar/39Ar technique as described in detail by Douglas.

    Steiger and Jaeger, 1977 (source 9 of 11)
    Steiger, R.H., and Jaeger, E., 1977, Subcommission on geochronology: Convention of the use of decay constants in geo- and cosmochronology: Earth and Planetary Science Letters v.36, no. 3.

    Other_Citation_Details: p. 359-362
    Type_of_Source_Media: paper
    Source_Contribution:
    Radiometric ages are quoted with a + 1 sigma level and calculated using the constants of Steiger and Jaeger.

    Cameron, 2000 (source 10 of 11)
    Cameron, C.E., 2000, Fault-hosted Au mineralization, Ester Dome, Alaska: University of Alaska, Fairbanks, University of Alaska, Fairbanks.

    Other_Citation_Details: 115 p.
    Type_of_Source_Media: paper
    Source_Contribution:
    Trace element analyses (Rb, Sr, Y, Nb, Zr) for 34 of the samples were performed at the University of Alaska, Fairbanks on splits of the pulverized samples using a Rigaku wavelength-dispersive XRF, and a routine created by Rainer Newberry (described in Cameron, 2000).

    McDougall and Harrison, 1988 (source 11 of 11)
    McDougall, Ian, and Harrison, T.M., 1988, Geochronology and thermochronology by the (super 40) Ar/ (super 39) Ar method: Oxford Monographs on Geology and Geophysics v. 9.

    Other_Citation_Details: 212 p.
    Type_of_Source_Media: paper
    Source_Contribution:
    In table 15, 40Ar*/39ArK (40*/39K) and ages (and 1-sigma error) were calculated using the equations and constants quoted in McDougall and Harrison (1988).

  2. How were the data generated, processed, and modified?

    Date: 1999 (process 1 of 10)
    Field work - During the summers of 1999 and 2000, the area was mapped on foot and over 400 geological stations were recorded and 300 samples collected. In many cases it was necessary to dig into tree roots and creek banks and dig test pits up to 1.5 meters deep.

    Date: Unknown (process 2 of 10)
    Field work - Placer Dome Exploration (PDX) conducted a large scale soil sampling program in the area and rock chip samples collected were saved for analysis.

    Date: Unknown (process 3 of 10)
    Lab - Cynthia Dusel-Bacon of the U.S, Geological Survey kindly loaned several thin-sections for examination use in microprobe studies. Florence Weber provided several boxes of collected samples to be examined to provide a regional framework.

    Date: Unknown (process 4 of 10)
    Lab - 36 metamorphic and 4 igneous hand specimens were etched and stained for quartz, plagioclase, and K-feldspar using the technique of Ruperto, V.L., Stevens, R.E., and Norman, M.B., 1964. K-feldspar acquired a bright yellow color, plagioclase stained red and quartz was unstained. Modal estimates were made either by standard point-counting using a minimum of 100 points, or by estimation by comparison to standard abundance charts. Modal abundances are listed in tables 1 and 2.

    Data sources used in this process:

    • Ruperto and others, 1964

    Date: Unknown (process 5 of 10)
    Lab - Major oxide analyses were performed by Bondar-Clegg, Incorporated, Vancouver, British Columbia, Canada on 39 rock samples, including 13 from drill core. Samples were crushed and pulverized in Fairbanks before pulps were shipped to Vancouver. Five of the samples were also analyzed for XRF trace elements by Bondar-Clegg, Incorporated.

    Date: Unknown (process 6 of 10)
    Lab - Microprobe data collected on biotite, garnet, white mica and K-feldspar were processed using the Macintosh Geothermobarometry program GTB (Spear and Kohn, 1999). Temperatures were calculated for 12 different garnet-biotite distribution models. Of these 12, those of Perchuk and Lavrenteva (1983) and Kleeman and Reinhardt (1994) with Berman (1990) produced similar, consistent temperatures intermediate to those of other models and were selected as most appropriate for biotite-garnet thermometry. Pressures were estimated based on the aluminosilicate stability diagram of Holdaway (1971), the calculated temperatures, and several compositional-based geobarometers (Spear, 1993). Geothermometry data are presented in table 7.

    Data sources used in this process:

    • Spear and Kohn, 1999
    • Perchuk and Lavrenteva, 1983
    • Kleeman and Reinhardt, 1994
    • Berman, 1990
    • Holdaway, 1971
    • Spear, 1993

    Date: Unknown (process 7 of 10)
    Lab - Microprobe analyses were performed on 6 polished sections of gneiss and 1 polished section from a gold-bearing vein, using the Cameca SX-50 electron microprobe and Probe for Windows software at the University of Alaska Fairbanks. Silicate compositions were measured using a 10 micron beam at 15 nA on wavelength dispersive spectrometers. Well-characterized natural and synthetic specimens were employed as standards. On-peak counts were collected for 10 seconds and background counts were collected for 5 seconds. Five points were selected for each silicate. This data was ZAF (atomic mass, absorbance, and fluorescence) corrected; following which poor-quality results were removed from the data set. Opaque minerals, including gold and bismuth, were identified in the gold-bearing vein using the EDS with a standardless analysis routine. Microprobe analyses are presented in table 8.

    Date: Unknown (process 8 of 10)
    Lab - Fluid inclusion experiments were performed at the USGS facility in Denver, Colorado, using a Linkam heating/freezing stage cooled with liquid nitrogen. All heating and cooling measurements were computer controlled, with standard-based calibrations performed prior to each session. Chips of a section up to 3 mm square were taken from eight doubly polished sections, 100 to 150 microns thick, and analyzed individually. The chips were broken from the section after the glue attaching the section to the slide was dissolved with acetone. Heating and cooling measurements were performed using Linksys, a windows-driven program, which has precision of 0.1 degree Celsius. Digital photographs of inclusions were taken within this program. The low-temperature measurements included CO2 melting temperatures and clathrate melting temperatures. All measurements except for final homogenization were performed systematically on each inclusion before moving onto the next. After several inclusions were measured, final homogenization temperatures were measured for as many inclusions as possible. Final homogenization observations were made for surrounding inclusions where possible. Once stretching of an inclusion was indicated (by non-repeatable heating experiments), no more homogenization measurements were collected from that chip. Fluid inclusion data is presented in table 9, 10 and 11.

    Date: Unknown (process 9 of 10)
    Lab - Five samples were dated using the 40Ar/39Ar technique, as described in detail by Douglas (1996). The samples were irradiated for 20 megawatt hours in a reactor at McMaster University along with standard sample MMHB-1 with age 513.9 Ma. The standard is used to estimate J, the irradiation parameter and the flux gradient of the reactor. The irradiated samples were then analyzed in the mass spectrometer at the University of Alaska Fairbanks geochronology laboratory, using an 40Ar/39Ar step heating routine 39-40 days after irradiation. The measured argon isotopes were corrected for mass discrimination as well as for interference of Ca, K, and CI produced from the reactor. Blanks (inlets) were run to determine background levels of argon. Sample measurements were corrected for this background argon. Ages are quoted with a + 1 sigma level and calculated using the constants of Steiger and Jaeger (1977). Argon dating results are presented in table 13 and 14.

    Data sources used in this process:

    • Douglas, 1996
    • Steiger and Jaeger, 1977
    • McDougall and Harrison, 1988

    Date: Unknown (process 10 of 10)
    Lab - Trace element analyses (Rb, Sr, Y, Nb, Zr) for 34 of the samples were performed at the University of Alaska, Fairbanks on splits of the pulverized samples using a Rigaku wavelength-dispersive XRF, and a routine created by Rainer Newberry (described in Cameron, 2000).

    Data sources used in this process:

    • Cameron, 2000

  3. What similar or related data should the user be aware of?

    Berman, R.G., 1990, Mixing properties of Ca-Mg-Fe-Mn garnets: American Mineralogist v. 75.

    Other_Citation_Details: p. 328-334
    Cameron, C.E, 2000, Fault-hosted Au mineralization, Ester Dome, Alaska: University of Alaska, Fairbanks, University of Alaska, Fairbanks.

    Other_Citation_Details: 115 p.
    Holdaway, M.J., 1971, Stability of andalusite and the aluminum silicate phase diagram: American Journal of Science v. 271.

    Other_Citation_Details: p. 97-131
    Kleeman, U., and Reinhardt, J., 1994, Garnet-biotite thermometry revisited: The effect of Al VI and Ti in biotite: European Journal of Mineralogy v. 6.

    Other_Citation_Details: p. 925-941
    Perchuk, L.L., and Lavrenteva, I.V., 1983, Experimental investigation of exchange equilibria in the system cordierite-garnet-biotite, in Saxena, S.K.: Springer Verlag, New York.

    Other_Citation_Details:
    in Saxena, S.K., ed., Kinetics and Equilibrium in Mineral Reactions, p. 199-240
    This is part of the following larger work.

    Saxena, S.K.(ed.), 1983, Kinetics and equilibrium in mineral reactions: Springer-Verlag, New York.

    Ruperto, V.L., Stevens, R.E., and Norman, M.B., 1964, Staining of plagioclase feldspars and other minerals with F.D. and C. Red No. 2: U.S. Geological Survey Professional Paper PP 501-B.

    Other_Citation_Details: p. B152-B153
    Spear, F.S., 1993, Metamorphic phase equilibria and pressure-temperature-time paths: Mineralogical Society of America, Washington, D.C..

    Other_Citation_Details: 799 p.
    Spear, F.S., and Kohn, M.J., 199905, Thermobarometry (GTB), Version 2.1.

    Steiger, R.H. (comp.), and Jaeger, E. (comp.), 1977, Subcommission on geochronology: Convention of the use of decay constants in geo- and cosmochronology: Earth and Planetary Science Letters v.36, no. 3.

    Other_Citation_Details: p. 359-362
    Angus, S., Armstrong, B., and Altunin, V., 1976, Carbon dioxide: International thermodynamic tables of the fluid state, Volume 3: Pergamon Press, Oxford.

    Other_Citation_Details: 385 p.
    Brown, P.E., and Lamb, W.M, 1989, PVT properties of fluids in the system H2O+/-CO2+/-NaCl; New graphical presentations and implications for fluid inclusion studies: Geochimica et Cosmochimica Acta v. 53, no. 6.

    Other_Citation_Details: p. 1209-1221
    Burruss, R.C., 1981, Analysis of phase equilibria in COHS fluid inclusions:.

    Other_Citation_Details:
    in Hollister, L.S., and Crawford, M.L., eds., Fluid inclusions; applications to petrology: Mineralogical Association of Canada Short Course, v. 6, p. 39-74
    This is part of the following larger work.

    Hollister, L.S.(ed.), and Crawford, M.L.(ed.), 1981, Fluid inclusions; applications to petrology: Mineralogical Association of Canada Short Course v. 6.

    Douglas, T.A., 1996, Metamorphic histories of the Chatanika eclogite and Fairbanks schist within the Yukon Tanana terrane, Alaska, as revealed by electron microprobe thermobarometry and 40Ar/39Ar single grain dating: University of Alaska Fairbanks, Fairbanks, Alaska.

    Other_Citation_Details: M.S. thesis, 240 p.
    Foster, H.L., Albert, N.R.D., Griscom, Andrew, Hessin, T.D., Menzie, W.D., Turner, D.L., and Wilson, F.H., 1979, The Alaskan Mineral Resource Assessment Program; Background information to accompany folio of geologic and mineral resource maps of the Big Delta Quadrangle, Alaska: U.S. Geological Survey Circular CIR 783.

    Other_Citation_Details: 19 p.
    Ganguly, Jibamitra, and Saxena, S.K., 1984, Mixing properties of aluminosilicate garnets; Constraints from natural and experimental data, and applications to geothermo-barometry: American Mineralogist v. 69, no. 12.

    Other_Citation_Details: p.88-97
    Ghent, E.D., and Stout, M.Z., 1981, Geobarometry and geothermometry of plagioclase-biotite-garnet-muscovite assemblages: Contributions to Mineralogy and Petrology v. 76, no. 1.

    Other_Citation_Details: p. 92-97
    Graham, G.E., 2002, Geology and gold mineralization of the Richardson district, east-central Alaska: University of Alaska Fairbanks, Fairbanks, Alaska.

    Other_Citation_Details: M.S. Thesis, 150 p.
    Hodges, K.V., and Crowley, P.D., 1985, Error estimation and empirical geothermobarometry for pelitic systems: American Mineralogist v. 70, no. 78.

    Other_Citation_Details: p. 702-709
    Hodges, K.V., and Spear, F.S., 1982, Geothermometry, geobarometry and the Al2SiO5 triple point at Mt. Moosilauke, New Hampshire: American Mineralogist v. 67, no. 1112.

    Other_Citation_Details: p. 1118-1134
    Hoisch, T.D., 1990, Empirical calibration of six geobarometers for the mineral assemblage quartz + muscovite + biotite + plagioclase + garnet: Contributions to Mineralogy and Petrology v. 104, no. 2.

    Other_Citation_Details: p. 225-234
    Kennedy, G.C., 1954, Pressure-volume-temperature relations in CO2 at elevated temperatures and pressures: American Journal of Science v. 252, no. 4.

    Other_Citation_Details: p. 225-241
    McCoy, D.T., Newberry, R.J., Layer, P.W., DiMarchi, J.J., Bakke, A.A., Masterman, J.S., and Minehane, D.L., 1997, Plutonic-related gold deposits of interior Alaska: Economic Geology Monographs v. 9.

    Other_Citation_Details: p.191-241
    Newton, R.C., and Haselton, H.T., 1981, Thermodynamics of the garnet plagioclase Al2SiO5 quartz geobarometer: Springer-Verlag, New York.

    Other_Citation_Details:
    in Newton, R.C., Navrotsky, Alexandra, and Wood, B.J., eds., Thermodynamics of minerals and melts, p. 131-147
    This is part of the following larger work.

    Newton, R.C.(ed.), Navrotsky, Alexandra(ed.), and Wood, B.J.(ed.), 1981, Thermodynamics of minerals and melts: Springer-Verlag, New York.

    Roedder, E.R., 1984, Fluid inclusions: Reviews in Mineralogy v. 12.

    Other_Citation_Details: 644 p
    McDougall, Ian, and Harrison, T.M., 1988, Geochronology and thermochronology by the (super 40) Ar/ (super 39) Ar method: Oxford Monographs on Geology and Geophysics v. 9.

    Other_Citation_Details: 212 p.
    Bundtzen, T.K., and Reger, R.D., 1977, The Richard lineament a structural control for gold deposits in the Richardson mining district, interior Alaska: Geologic Report GR 55, Alaska Geological & Geophysical Surveys, Fairbanks, AK.

    Other_Citation_Details: p. 29-34
    This is part of the following larger work.

    Alaska Geological & Geophysical Surveys, 1977, Short Notes on Alaskan Geology - 1977: Geologic Report GR 55, Alaska Geological & Geophysical Surveys, Fairbanks, AK.

    Other_Citation_Details: 50 p.
    Pakhomova, V., Belyaeva, V., and Tishkin, B., 1995, Results of a thermobarometric study of hydrothermal fluids and magmatic system at the Democrat lode deposit, Richardson district, Alaska: Alaska Miners Association Special Symposium v. 1, Glacier House Publications, Anchorage, Alaska.

    Other_Citation_Details: p. 128-133
    This is part of the following larger work.

    Bundtzen, T.K. (ed.), Fonseca, A.L. (ed.), and Mann, Roberta (ed.), 1995, The Geology and Mineral Deposits of the Russian Far East: Alaska Miners Association Special Symposium v. 1, Glacier House Publications, Anchorage, Alaska.


How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?

    Placer Dome Exploration (PDX) conducted a large-scale soil sampling program in the area in 1999 and 2000. Hand samples were also collected from various locations during concurrent geologic mapping. The geochemical results from these activities were used to determine subsequent core drilling in both 1999 and 2000. Thirty thin sections, 15 doubly-polished from vein samples, 12 polished sections, and one white mica separate were used from the core drilled by PDX during 1999 and 2000. This core was halved with a rock saw with one-half of each interval sent for assay and the other retained for additional studies. Modal estimates were conducted on 36 metamorphic and four igneous hand specimens that were etched and stained for quartz, plagioclase, and K-feldspar using the technique of Ruperto and others (1964). K-feldspar assumed a bright yellow color, plagioclase stained red, and quartz remained unstained. Modal estimates were made either by standard point-counting using a minimum of 100 points, or by estimation by comparison to standard abundance charts. Modal abundances are listed in tables 2 and 3. Major- and minor-oxide analyses were performed by Bondar-Clegg, Incorporated, Vancouver, British Columbia, Canada, on 39 rock samples, including 13 from drill core. Samples were crushed and pulverized in Fairbanks before pulps were shipped to Vancouver. Major- and minor-oxide results, including normative values, are listed in tables 4, 5 and 6. Trace-element analyses for 34 of the samples were performed at the University of Alaska Fairbanks on splits of the pulverized samples using a Rigaku energy-dispersive XRF and a routine created by Rainer Newberry (described in Cameron, 2000). The results of 16 of the samples are listed in tables 5 and 7. Replicate and secondary standard analyses for commercial and UAF XRF analyses indicate major oxides are accurate to within 2 percent of the amount present, while trace elements are accurate to within 510 percent of the amount present (Cameron, 2000). Microprobe data collected on biotite, garnet, white mica, and K-feldspar were processed using the Macintosh Geothermobarometry program GTB (Spear and Kohn, 1999). Temperatures were calculated for 12 different garnet-biotite distribution models. Of these 12, those of Perchuk and Lavrenteva (1984) and Kleeman and Reinhardt (1994) with Berman (1990) produced similar, consistent temperatures intermediate to those of other models and were selected as most appropriate for biotite-garnet thermometry. Pressures were estimated based on the calculated temperatures, the aluminosilicate stability diagram of Holdaway (1971), and several compositional-based geobarometers (Spear, 1993). Geothermometry data are presented in table 8. Microprobe analyses were performed on six polished sections of gneiss and one polished section from a gold-bearing vein, using the Cameca SX-50 electron microprobe and Probe for Windows software at the University of Alaska Fairbanks. Silicate compositions were measured using a 10 micron beam at 15 nA on wavelength-dispersive spectrometers. Well-characterized natural and synthetic specimens were employed as standards. On-peak counts were collected for 10 seconds and background counts were collected for 5 seconds. Five points were selected for each silicate. These data were ZAF (atomic mass, absorbance, and fluorescence) corrected and poor-quality results were removed from the data set. Opaque minerals, including gold and bismuth, were identified in the gold-bearing vein using the EDS with a standardless analysis routine. Microprobe analyses are presented in table 9. Fluid inclusion experiments were performed at the USGS facility in Denver, Colorado, using a Linkam heating/freezing stage cooled with liquid nitrogen. All heating and cooling measurements were computer controlled, with standard-based calibrations performed prior to each session. Chips of a section up to 3 mm2 were taken from eight doubly-polished sample sections, 100 to 150 microns thick, and analyzed individually. The chips, attached by glue to the slide, were removed from the section using acetone. Heating and cooling measurements were performed using Linksys, a Windows-driven program, which has a precision of 0.1 Celsius. The low-temperature measurements included CO2 and clathrate melting temperatures. All measurements except for final homogenization were performed systematically on each inclusion before moving on to the next. After several inclusions were measured, final homogenization temperatures were measured for as many inclusions as possible. Final homogenization observations were made for surrounding inclusions where possible. Once stretching of an inclusion was indicated (by non-repeatable heating experiments), no more homogenization measurements were collected from that chip. Fluid inclusion data are presented in tables 10, 11, and 12. Five samples were dated using the 40Ar/39Ar technique, as described in detail by Douglas (1996). The samples were irradiated for 20 megawatt hours in a reactor at McMaster University along with standard sample MMHB-1 with age 513.9 Ma. The standard is used to estimate J, the irradiation parameter and the flux gradient of the reactor. The irradiated samples were then analyzed in the mass spectrometer at the University of Alaska Fairbanks geochronology laboratory, using an 40Ar/39Ar step heating routine 3940 days after irradiation. The measured argon isotopes were corrected for mass discrimination as well as for interference of Ca, K, and Cl produced from the reactor. Blanks (inlets) were run to determine background levels of argon, and measurements were corrected for the background argon. Ages are quoted with a 1 sigma level and calculated using the constants of Steiger and Jaeger (1977). Argon dating results are presented in table 13. The proposed geological events for the Richardson area, based on the radiometric dating, are presented in table 14. Table 15 lists the 40Ar/39Ar step-heating results and data.

  2. How accurate are the geographic locations?

    Location data is in UTM coordinates with a Clark 1866, NAD27, UTM zone 6 projection. Locations were measured using a Garmin GPS handheld unit.

  3. How accurate are the heights or depths?

  4. Where are the gaps in the data? What is missing?

    Not all data analyzed was included in this report.

  5. How consistent are the relationships among the observations, including topology?

    No topologic relationships are present in the data.


How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?

Access_Constraints:
This report, map, and/or dataset are available directly from the State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys (see contact information below).
Use_Constraints:
Any hard copies or published datasets utilizing these datasets shall clearly indicate their source. If the user has modified the data in any way, the user is obligated to describe the types of modifications the user has made. User specifically agrees not to misrepresent these datasets, nor to imply that changes made by the user were approved by the State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys.

  1. Who distributes the data set? (Distributor 1 of 1)

    State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys
    3354 College Road
    Fairbanks, AK 99709-3707
    USA

    907-451-5020 (voice)
    907-451-5050 (FAX)
    dggspubs@alaska.gov

    Hours_of_Service: 8 am to 4:30 pm, Monday through Friday, except State holidays
    Contact_Instructions:
    Please view our web site (<http://www.dggs.dnr.state.ak.us>) for the latest information on available data. Please contact us using the e-mail address provided above when possible.
  2. What's the catalog number I need to order this data set?

    Raw Data File 2007-2

  3. What legal disclaimers am I supposed to read?

    The State of Alaska makes no express or implied warranties (including warranties of merchantability and fitness) with respect to the character, function, or capabilities of the electronic services or products or their appropriateness for any user's purposes. In no event will the State of Alaska be liable for any incidental, indirect, special, consequential, or other damages suffered by the user or any other person or entity whether from the use of the electronic services or products, any failure thereof, or otherwise, and in no event will the State of Alaska's liability to the requester or anyone else exceed the fee paid for the electronic service or product.

  4. How can I download or order the data?

  5. What hardware or software do I need in order to use the data set?

    CSV (Comma Separated Value) files can be imported and formatted with Microsoft Excel, OpenOffice.org Calc, or most spreadsheet and text editor programs.


Who wrote the metadata?

Dates:
Last modified: 06-May-2008
Last Reviewed: 06-May-2008
To be reviewed: 05-Sep-2009
Metadata author:
Diana Jozwik
State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys
3354 College Road
Fairbanks, Alaska 99709-3707

907-451-5010 (voice)
907-451-5050 (FAX)
dggspubs@alaska.gov

Hours_of_Service: 8 am to 4:30 pm, Monday through Friday, except State holidays.
Contact_Instructions:
Please contact us through the e-mail address above whenever possible.
Metadata standard:
FGDC Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)


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