Geologic Map of the Eagle A-2 Quadrangle, Fortymile mining district, Alaska

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What does this data set describe?

Title:
Geologic Map of the Eagle A-2 Quadrangle, Fortymile mining district, Alaska
Abstract:
The Alaska Division of Geological & Geophysical Surveys (DGGS) has conducted 1:63,360-scale geologic mapping of the Eagle A-2 Quadrangle (270 square miles; equivalent to four 7.5-minute quadrangles). The area is part of the 100-year old Fortymile mining district and is located in eastern Alaska near the Alaska-Yukon border. This geologic map was produced by merging a bedrock geologic map and a surficial geologic map of the Eagle A-2 Quadrangle and based upon results from field investigations by DGGS in 1999 and 2000, which were part of a three-year mapping program to provide geologic ground truth for airborne geophysical surveys flown by DGGS in the Fortymile mining district during 1998.
Supplemental_Information:
The layers listed below are present as ArcGIS shape files. Attribute information for the following layers (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." Basic unit information is also included in the unit code set file "PIR2001-3_codeset.pdf." Layers include:
fmarpoints     locations of Ar/Ar analyses samples
fmcompcont     geologic bedrock contacts under surficial geology
fmcompdikes     dike locations (arc)
fmcompfolds     fold axis (anticline or syncline) traces
fmcompgeo     comprehensive geologic units
fmdikepoints     dike locations (point)
fmfaults_arc     fault contacts (arc)
fmfaults_point     fault symbols (point)
fmfoldsym     symbols for folds, anticlines, synclines, and bedding features
fmkyanitepts     locations where the mineral kyanite was found
fmpingos     pingo locations
fmstrike     lineaments and bedding planes
  1. How should this data set be cited?

    Werdon, M.B., Newberry, R.J., Szumigala, D.J., and Pinney, D.S., 200105, Geologic Map of the Eagle A-2 Quadrangle, Fortymile mining district, Alaska: Preliminary Interpretive Report PIR 2001-3A, State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys (DGGS), Fairbanks, AK, USA.

    Online Links:

    Other_Citation_Details: 1 sheet, scale 1:63,360

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -142.00902346
    East_Bounding_Coordinate: -141.49552824
    North_Bounding_Coordinate: 64.25256429
    South_Bounding_Coordinate: 63.9974188

  3. What does it look like?

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

    Beginning_Date: 1999
    Ending_Date: 2001
    Currentness_Reference: publication date

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

    Geospatial_Data_Presentation_Form: map, vector digital data

  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?

      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:
      UTM_Zone_Number: 7
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.999600
      Longitude_of_Central_Meridian: -141.000000
      Latitude_of_Projection_Origin: 0.000000
      False_Easting: 500000.000000
      False_Northing: 0.000000

      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest 0.000064
      Ordinates (y-coordinates) are specified to the nearest 0.000064
      Planar coordinates are specified in Meters

      The horizontal datum used is D_Clarke_1866.
      The ellipsoid used is Clarke 1866.
      The semi-major axis of the ellipsoid used is 6,378,206.400000.
      The flattening of the ellipsoid used is 1/294.978698.

  7. How does the data set describe geographic features?

    fmarpoints.shp
    Object type is point, there are 13 rows associated with this entity, and the entity values refer to locations of Ar/Ar analyses samples (Source: Alaska Division of Geological & Geophysical Surveys)

    STATIONNO
    Generic example of unique sample identifier or location of a geologic measurement: YrAAA999X: Yr=2 digit year of sample collection, AAA=geologist's initials (one to three characters), 999=unique station number, X=unique alpha character designating a sample was taken at the field station. Geologists' initials are: MBW - M. Werdon, DS - D. Szumigala, and RN - R. Newberry. (Source: Alaska Division of Geological & Geophysical Surveys)

    Unique sample number designated by the author(s).

    UTME
    easting, UTM Zone 7 NAD 27 (Source: Alaska Division of Geological & Geophysical Surveys)

    Range of values
    Minimum:453852
    Maximum:475609
    Units:meters

    UTMN
    northing, UTM Zone 7 NAD 27 (Source: Alaska Division of Geological & Geophysical Surveys)

    Range of values
    Minimum:7097379
    Maximum:7122073
    Units:meters

    LABLE
    number assigned to each Ar/Ar location (Source: Alaska Division of Geological & Geophysical Surveys)

    Unique number assigned to each sample so there is no known domain.

    ARNUMBER
    number assigned to each Ar/Ar sample location (Source: Alaska Division of Geological & Geophysical Surveys)

    Actual unique symbol used on map for each Ar/Ar location

    X-COORD
    easting, UTM Zone 7 NAD 27 (Source: Alaska Division of Geological & Geophysical Surveys)

    Range of values
    Minimum:453852
    Maximum:475609
    Units:meters

    Y-COORD
    northing, UTM Zone 7 NAD 27 (Source: Alaska Division of Geological & Geophysical Surveys)

    Range of values
    Minimum:7097379
    Maximum:7122073
    Units:meters

    fmcompcont.shp
    Object type is vector, there are 2447 rows associated with this entity, and the entity values refer to geologic bedrock contacts under surficial geology (Source: Alaska Division of Geological & Geophysical Surveys)

    CODE
    geologic bedrock contacts under surficial geology (Source: Alaska Division of Geological & Geophysical Surveys)

    ValueDefinition
    0Hidden line, defines the polygon boundary, but is not displayed on the map for aesthetic purposes
    7contact inferred
    9contact concealed

    SURFBED
    what portions of contacts are under surficial cover as opposed to exposed bedrock (Source: Alaska Division of Geological & Geophysical Surveys)

    ValueDefinition
    Ssurficial
    Bbedrock

    fmcompfolds.shp
    Object type is vector, there are 353 rows associated with this entity, and the entity values refer to fold axis (anticline or syncline) traces. ***Note: This entity type is used in conjunction with the entity "fmfoldsym" (see below) to signify the type of fold (i.e. anticline or syncline).*** (Source: Alaska Division of Geological & Geophysical Surveys)

    SURFBED
    Surficial cover or exposed bedrock (Source: Alaska Division of Geological & Geophysical Surveys)

    ValueDefinition
    Ssurficial
    Bbedrock

    CODE
    fold axis (anticline or syncline) traces under surficial cover or exposed bedrock (Source: Alaska Division of Geological & Geophysical Surveys)

    ValueDefinition
    35Anticline or syncline, approximately located
    38Anticline or syncline, concealed

    fmfoldsym.shp
    Object type is point, there are 85 rows associated with this entity, and the entity values refer to symbols for folds, anticlines, synclines, and bedding features (Source: Alaska Division of Geological & Geophysical Surveys)

    TYPE
    fold types (Source: Alaska Division of Geological & Geophysical Surveys)

    ValueDefinition
    aanticline
    ssyncline
    oaoverturned anticline
    osoverturned syncline

    CODE
    symbols representing type of folds (Source: Alaska Division of Geological & Geophysical Surveys)

    ValueDefinition
    22Anticline
    23Syncline
    27Overturned anticline, showing direction of dip of limbs
    26Overturned syncline, showing direction of dip of limbs

    fmcompgeo.shp
    Object type is vector, there are 1601 rows associated with this entity, and the entity values refer to comprehensive geologic units (Source: Alaska Division of Geological & Geophysical Surveys)

    UNIT
    comprehensive geologic unit labels, any unit ending with a "?" indicates uncertainty (Source: Alaska Division of Geological & Geophysical Surveys)

    ValueDefinition
    lakepolygons defining a lake

    Formal codeset
    Codeset Name:PIR2001-3_codeset.pdf
    Codeset Source:Alaska Division of Geological & Geophysical Surveys

    X-COORD
    Easting, UTM Zone 7 NAD 27 (Source: Alaska Division of Geological & Geophysical Surveys)

    Range of values
    Minimum:451156.20980409
    Maximum:475701.268132906
    Units:meters

    Y-COORD
    Northing, UTM Zone 7 NAD 27 (Source: Alaska Division of Geological & Geophysical Surveys)

    Range of values
    Minimum:7096973.31683337
    Maximum:7124913.26553537
    Units:meters

    MAT
    engineering-materials units. See the Engineering-Geologic Map of the Eagle A-2 Quadrangle, Fortymile mining district, Alaska (DGGS publication PIR 2001-3D) for more information. (Source: Alaska Division of Geological & Geophysical Surveys)

    ValueDefinition
    GSFluvial and glaciofluvial gravel, sand and silt. Chiefly (estimated >80 percent) clean sand and gravel.
    GMPoorly- to moderately well-sorted clay, silt, sand, gravel, and diamicton of colluvial, fluvial and glacial origins. Includes angular, unsorted talus debris and chaotically deformed colluvium derived from landslides.
    SMSilt deposited primarily by wind and reworked by fluvial and colluvial processes. May be organic rich.
    OROrganic-rich silt and peat in bogs, former stream channels, and lake basins. Commonly frozen ice-rich due to the excellent insulating properties of peat.
    BCMedium-jointed, fine- to coarse-grained sedimentary carbonate rocks and their metamorphic equivalents. Includes limestone and marble
    BGCoarse-jointed, coarse-grained igneous lithologies and their metamorphic equivalents. Chiefly granitic rocks. Includes coarse-grained gneiss.
    BMMedium-jointed, fine- to medium-grained quartzose sedimentary rocks and their metamorphic equivalents. Chiefly quartzite in this map area.
    BVMedium-jointed, fine-grained igneous rocks and their metamorphic equivalents. Chiefly metavolcanics and dikes
    BORocks of lithologies: (a) not listed in other materials classes, but which may be suited for use as construction materials or for other specialized purposes; and (b) mixed units composed of combinations of the above bedrock materials classes. Includes fine-grained gneiss and phyllite.
    BURocks of mixed lithology and/or very fine-grained sedimentary lithologies that are generally poorly suited for use as construction materials. Includes coal-bearing Tertiary sediments.

    fmcompdikes.shp
    Object type is vector, there are 72 rows associated with this entity, and the entity values refer to dike locations (Source: Alaska Division of Geological & Geophysical Surveys)

    CODE
    line symbols for various lineaments (Source: Alaska Division of Geological & Geophysical Surveys, PIR 2001-3a Description of Map Units)

    ValueDefinition
    57dikes

    SURFBED
    Surficial cover or exposed bedrock (Source: Alaska Division of Geological & Geophysical Surveys)

    ValueDefinition
    Ssurficial
    Bbedrock

    fmdikepoints.shp
    Object type is point, there are 217 rows associated with this entity, and the entity values refer to dike locations (Source: Alaska Division of Geological & Geophysical Surveys)

    NOTE
    unique station location representing year, geologist, and station number (Source: Alaska Division of Geological & Geophysical Surveys)

    unique value given to every station based on the year, who is creating the station and the number system that they decide on.

    UTME
    easting, UTM Zone 7, NAD 27 (Source: unknown)

    Range of values
    Minimum:451314
    Maximum:475609
    Units:meters

    UTMN
    northing, UTM Zone 7, NAD 27 (Source: unknown)

    Range of values
    Minimum:7097489
    Maximum:7124732
    Units:meters

    DIKETYPE
    type of dike (Source: Alaska Division of Geological & Geophysical Surveys)

    ValueDefinition
    4pegmatite dike
    8granite dike
    12gabbro dike
    6clinopyroxenite dike
    9diabase dike
    5aplite
    111granite dike (?)
    13felsic dike, general
    4.5(?)
    1meta-aplite
    2quartz monzonite
    3intermediate dike
    140aplite-pegmatite dike (?)
    11tertiary basalt
    14gabbro in TMB (?) or porphyritic granodiorite
    15Iamprophyre

    AZIM
    orientation of the strike, based on "right hand rule" and zero equals north counting clockwise, magnetic declination was 27.7 degrees (Source: Comptons)

    Range of values
    Minimum:0
    Maximum:360
    Units:degrees

    EAZIM
    zero equals east, counterclockwise counting, orientation of strike "right hand rule" engineering method, magnetic declination was 27.7 degrees. (Source: ArcView, ESRI)

    Range of values
    Minimum:0
    Maximum:360
    Units:degrees

    DIP
    dip orientation (Source: Alaska Division of Geological & Geophysical Surveys)

    Range of values
    Minimum:0
    Maximum:90
    Units:degrees from horizontal

    AI-MSET
    ArcInfo marker set (Source: ESRI, ArcInfo)

    user needs to look up information in ArcInfo marker set

    AI-SYMB
    actual symbols within the marker sets listed in AI-MSET (Source: ESRI, ArcInfo)

    ValueDefinition
    21plotter.mrk
    97plotter.mrk
    29plotter.mrk
    49plotter.mrk
    126plotter.mrk
    126water.mrk
    138water.mrk
    107water.mrk
    109water.mrk
    107mineral.mrk
    103mineral.mrk
    103oilgas.mrk

    ROOTNAME
    simple name of dike type (Source: Alaska Division of Geological & Geophysical Surveys)

    made up list of values by DGGS with no short name.

    FIELD_NOTE
    description of dike type, lithology, and filed station from field descriptions (Source: Alaska Division of Geological & Geophysical Surveys)

    produced from field notes so there is no domain already established.

    fmfaults_arc.shp
    Object type is vector, there are 161 rows associated with this entity, and the entity values refer to fault contacts (Source: Alaska Division of Geological & Geophysical Surveys)

    CODE
    location and type of fault (Source: Alaska Division of Geological & Geophysical Surveys)

    ValueDefinition
    12Fault, approximately located
    16Fault, hypothetical
    19Thrust fault, inferred

    fmfaults_point.shp
    Object type is point, there are 5 rows associated with this entity, and the entity values refer to fault motion (Source: Alaska Division of Geological & Geophysical Surveys)

    SYMBOL
    showing location where fault movement is discernible (Source: Alaska Division of Geological & Geophysical Surveys)

    ValueDefinition
    25Relative horizontal movement along fault

    fmkyanitepts.shp
    Object type is point, there are 8 rows associated with this entity, and the entity values refer to sample locations where the mineral kyanite was found (Source: Alaska Division of Geological & Geophysical Surveys)

    SAMPLENO
    Generic example of unique sample identifier or location of a geologic measurement: YrAAA999X: Yr=2 digit year of sample collection, AAA=geologist's initials (one to three characters), 999=unique station number, X=unique alpha character designating a sample was taken at the field station. Geologists' initials are: MBW - M. Werdon, DS - D. Szumigala, and RN - R. Newberry. (Source: Alaska Division of Geological & Geophysical Surveys)

    Unique sample number designated by the author(s).

    UTME
    Easting, UTM Zone 7 NAD 27 (Source: Alaska Division of Geological & Geophysical Surveys)

    Range of values
    Minimum:462333
    Maximum:475609
    Units:meters

    UTMN
    Northing, UTM Zone 7 NAD 27 (Source: Alaska Division of Geological & Geophysical Surveys)

    Range of values
    Minimum:7097953
    Maximum:7114943
    Units:meters

    LABEL
    The letter "K" plotted on the map, signifying the sample location. (Source: Alaska Division of Geological & Geophysical Surveys)

    Unique label designated by the author(s).

    fmpingos.shp
    Object type is point, there are 2 rows associated with this entity, and the entity values refer to pingo locations (Source: Alaska Division of Geological & Geophysical Surveys)

    TEMP
    attribute describing the object pingo (Source: Alaska Division of Geological & Geophysical Surveys)

    The description is not from any specific domain

    UNIT
    attribute describing the object pingo (Source: Alaska Division of Geological & Geophysical Surveys)

    The description is not from any specific domain

    SUNIT
    attribute describing the object pingo (Source: Alaska Division of Geological & Geophysical Surveys)

    The description is not from any specific domain

    SURFBED
    what portions of contacts are under surficial cover as opposed to exposed bedrock (Source: Alaska Division of Geological & Geophysical Surveys)

    ValueDefinition
    SFluvial and glaciofluvial gravel, sand, and silt. Chiefly (estimated >80 percent) clean sand and gravel. Grain size, sorting and degree of stratification are variable.

    fmstrike.shp
    Object type is point, there are 561 rows associated with this entity, and the entity values refer to lineaments and bedding planes (Source: Alaska Division of Geological & Geophysical Surveys)

    LONG
    easting, UTM Zone 7, NAD 27 (Source: unknown)

    Range of values
    Minimum:451594
    Maximum:475614
    Units:meters

    LAT
    northing, UTM Zone 7, NAD 27 (Source: unknown)

    Range of values
    Minimum:7097691
    Maximum:7124971
    Units:meters

    STATION
    Generic example of unique sample identifier or location of a geologic measurement: YrAAA999X: Yr=2 digit year of sample collection, AAA=geologist's initials (one to three characters), 999=unique station number, X=unique alpha character designating a sample was taken at the field station. Geologists' initials are: MBW - M. Werdon, DS - D. Szumigala, JG - J. Grady, RN - R. Newberry, and WM - W. Munley. (Source: Alaska Division of Geological & Geophysical Surveys)

    Unique sample number designated by the author(s).

    TYPE
    type of structures (Source: Alaska Division of Geological & Geophysical Surveys)

    ValueDefinition
    ffoliation
    vfvertical foliation
    bbedding

    AZIMUTH
    orientation of the strike, based on "right hand rule" and zero equals north counting clockwise, magnetic declination was 27.7 degrees (Source: Comptons)

    Range of values
    Minimum:0
    Maximum:360
    Units:degrees

    ARC-AZIMUTH
    zero equals East, counterclockwise counting orientation of strike, "right hand rule" engineering method, magnetic declination was 27.7 degrees (Source: ESRI, ArcView)

    Range of values
    Minimum:0
    Maximum:360
    Units:degrees

    DIP
    dip orientation (Source: Alaska Division of Geological & Geophysical Surveys)

    Range of values
    Minimum:0
    Maximum:90
    Units:degrees from horizontal

    SYMBOL
    map symbols for bedding and foliation (Source: Alaska Division of Geological & Geophysical Surveys)

    ValueDefinition
    9foliation strike/dip
    10vertical foliation strike/dip
    1bedding strike/dip

    X-COORD
    easting, UTM Zone 7, NAD 27 (Source: unknown)

    Range of values
    Minimum:451594
    Maximum:475614
    Units:meters

    Y-COORD
    northing, UTM Zone 7, NAD 27 (Source: unknown)

    Range of values
    Minimum:7097691
    Maximum:7124971
    Units:meters

    ANGLE
    strike direction (Source: Alaska Division of Geological & Geophysical Surveys)

    Range of values
    Minimum:0
    Maximum:360
    Units:degrees


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?

    This project is part of the Alaska Airborne Geophysical/Geological Mineral Inventory Program funded by the Alaska State Legislature and managed by State of Alaska, Department of Natural Resources (DNR), Division of Geological & Geophysical Surveys (DGGS). Partial funding for the geologic mapping was also provided by the U.S. Geological Survey, National Cooperative Geologic Mapping Program, under STATEMAP award number 00HQAG0071 under the NCGM STATEMAP program for FY2000. The views and conclusions contained in this document are those of the authors and should not be interpreted as necessarily representing the official policies, either expressed or implied, of the U.S. government.

  3. To whom should users address questions about the data?

    State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys
    GIS Data Manager/Cartographer
    3354 College Road
    Fairbanks, AK 99709-3707

    (907) 451-5029 (voice)
    (907) 451-5050 (FAX)
    dggspubs@alaska.gov

    Contact_Instructions:
    You may view our web site at <http://www.dggs.dnr.state.ak.us> for the latest information on available data. Please e-mail your questions and data requests when possible since our web site and e-mail address will remain current even if our phone number and mailing address change.


Why was the data set created?

This project, resulting map, geospatial data are intended to provide a geologic map and a geologic interpretation of the Fortymile mining district at 1:63,360 scale. Previous published 1:63,360 scale geologic maps of this area have been reconnaissance-level maps or only covered portions of the quadrangle. Mapping at 1:63,360 scale (or more detailed) is needed to identify critical geologic features that may relate to more regional structures or geologic units. These detailed observations are also critical to test or use in tectonic models. This map also provides a geologic base in which to interpret geochemical results from the concurrent DGGS rock sampling program.


How was the data set created?

  1. From what previous works were the data drawn?

    Foster, 1969 (source 1 of 7)
    Foster, H.L., 1969, Reconnaissance geology of the Eagle A-1 and A-2 Quadrangles, Alaska: U.S. Geological Survey Bulletin B 1271-G, United States Government Printing Office, Washington D.C., Maryland.

    Other_Citation_Details: 30 p.
    Type_of_Source_Media: paper
    Source_Scale_Denominator: 63360
    Source_Contribution: See this publication cited in the Process Step section below.

    Newberry and others, 1998 (source 2 of 7)
    Newberry, R.J., Layer, P.W., Solie, D.N., and Burleigh, R.E., 1998, New 40Ar/39Ar dates for intrusions and mineral prospects in the eastern Yukon-Tanana Terrane, Alaska- regional patterns and significance:.

    This is part of the following larger work.

    Gray, J.E. (ed.), and Riehle, J.R. (ed.), 1998, Geologic studies in Alaska by the USGS, 1996: US Geological Survey Professional Paper 1595, United States Government Printing Office, Washington D.C., Maryland.

    Other_Citation_Details: Used pages 131-159 from this publication
    Type_of_Source_Media: paper
    Source_Contribution: See this publication cited in the Process Step section below

    Szumigala and others, 2000 (source 3 of 7)
    Szumigala, D.J., Newberry, R.J., Werdon, M.B., Finseth, B.A., Pinney, D.S., and Flynn, R.L., 200004, Major-oxide, minor-oxide, trace-element, and geochemical data from rocks collected in a portion of the Fortymile mining district, Alaska, 1999: Raw Data File RDF 2000-1, State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys, Fairbanks, AK.

    Online Links:

    Other_Citation_Details: 26 p., 2 sheets
    Type_of_Source_Media: paper, online, CD-ROM
    Source_Contribution: See this publication cited in the Process Step section below

    Werdon and others, 2000 (source 4 of 7)
    Werdon, M.B., Szumigala, D.J., Newberry, R.J., Grady, J.C., and Munly, W.C., 2000, Major oxide, minor oxide, trace element, rare-earth element, and geochemical data from rocks collected in Eagle and Tanacross quadrangles, Alaska in 2000: Raw Data File RDF 2000-4, State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys, Fairbanks, AK.

    Online Links:

    Other_Citation_Details: 27 p., 3 sheets
    Type_of_Source_Media: paper, online, CD-ROM
    Source_Contribution: See this publication cited in the Process Step section below

    DGGS and others, 1999 (source 5 of 7)
    Alaska Division of Geological & Geophysical Surveys, Geoterrex-Dighem, and Stevens Exploration Inc. Staff, 199901, Profile and gridded data and section lines of 1998 geophysical survey data for part of the Fortymile mining district, Alaska, southern Eagle and northern Tanacross quadrangles: Public Data File PDF 99-9, State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys, Fairbanks, AK.

    Online Links:

    Other_Citation_Details: 2 CD-ROMs
    Type_of_Source_Media: paper, online, CD-ROM
    Source_Contribution: See this publication cited in the Process Step section below

    Naeser and others, 1982 (source 6 of 7)
    Naeser, N.D., Westgate, J.A., Hughes, O.L., and Pewe, T.L., 1982, Fission-track ages of late Cenozoic distal tephra beds in the Yukon Territory and Alaska: Canadian Journal of Earth Sciences Vol. 19, Canadian Journal of Earth Sciences, Canada.

    Other_Citation_Details: p. 2167-2178
    Type_of_Source_Media: paper
    Source_Contribution: See this publication cited in the Process Step section below

    Yeend, 1996 (source 7 of 7)
    Yeend, Warren, 1996, Gold placers of the historical Fortymile River region, Alaska: U.S. Geological Survey Bulletin 2125, United States Government Printing Office, Washington D.C., Maryland.

    Other_Citation_Details: 74 p., 1 sheet
    Type_of_Source_Media: paper
    Source_Scale_Denominator: 63360
    Source_Contribution: See this publication cited in the Process Step section below

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

    Date: 2000 (process 1 of 7)
    Fieldwork- Fieldwork for bedrock investigations, including ridge traverses, road cut investigations, and river exposures, was conducted for 350 person-days during the months of June through August in 1999 and 2000. Field notes and rock samples were collected at over 2,550 stations located throughout the quadrangle for bedrock investigations. Fifty person-days were spent on field investigations for the surficial geology. Bedrock mapping involved using DGGS and others (1999) on a daily basis for checking geologic contacts and units. Bedrock mappers recorded observations on 1:50,000 scale topographic maps of the quadrangle. Stations located using hand held GPS devices with location precision varying from +/-3 to 15 meters.

    Data sources used in this process:

    • DGGS and others, 1999

    Date: 2000 (process 2 of 7)
    Fieldwork- Fieldwork for surficial investigations, including traverses, road cut investigations, and river exposures, was conducted for 50 person-days during the months of June through August in 1999 and 2000. Field notes and sediment samples were collected throughout the quadrangle for surficial investigations. Surficial mapping involved using Yeend (1996) on a regular basis for checking placer geology and general units. Surficial mappers recorded observations on 1:50,000 scale (nominal) color-infrared aerial photographs and 1:63,360 scale topographic base maps. Stations located using air photos and hand held GPS devices with location precision varying from +/-3 to 15 meters.

    Data sources used in this process:

    • Yeend, 1996

    Date: 2000 (process 3 of 7)
    Laboratory data compilation- Laboratory analyses were performed on rock samples collected during the fieldwork process step from July 1999 intermittently through April 2001. Published geochemical and age results are found in Szumigala and others (2000) and Werdon and others (2000). Unpublished laboratory results include petrographic work on thin sections and modal analysis of rock slabs stained for plagioclase and potassium feldspar. Results from major oxide and trace element geochemistry of igneous and metamorphic rocks were used to calculate CIPW Norms for use in classifying rocks according to established petrologic nomenclature. Thin sections produced by this study are currently stored at the DGGS office in Fairbanks, Alaska. Rock samples, including geochemical sample pulps and rock hand samples from most field stations, are currently stored at the DGGS office in Fairbanks. Final storage for most rock samples generated by this study will be at the DGGS Geologic Materials Center (GMC) in Eagle River, Alaska.

    Data sources used in this process:

    • Szumigala and others, 2000
    • Werdon and others, 2000

    Date: 2000 (process 4 of 7)
    Laboratory data compilation- Laboratory analyses were performed on radiocarbon samples and gold-bearing gravel samples from June 1999 intermittently through April 2001. Unanalyzed radiocarbon and tephra samples are currently stored at the DGGS office in Fairbanks. Final storage for most samples generated by this study will be at the DGGS Geologic Material Center (GMC) in Eagle River, Alaska.

    Date: 2000 (process 5 of 7)
    Geologic map compilation- Bedrock geologic map was compiled using field notes from fieldwork process step (above), analytical results from laboratory data compilation process step (above), and all known geologic data from previous work in quadrangle. The main sources of existing data include Foster (1969), Newberry and others (1988), DGGS and others (1999), Szumigala and others (2000), and Werdon and others (2000). Data was compiled on multiple layers of stable mylar at 1:50,000 scale, with some information plotted at 1:24,000 scale for more detail and later transferred to 1:50,000 scale mylar layers. Relevant information from all mylar layers was compiled onto one stable mylar sheet with abundant control points. The compilation mylar was scanned by a large-format scanner and saved as a TIFF image. The TIFF image was imported into ArcView GIS Version 3.1? distributed by ESRI, Inc., then co-registered to a georeferenced 1:63,360-scale USGS topographic base. Geologic contacts and unit polygons were digitized on-screen in ArcView.Station-specific information such as structural measurements, location of age samples, and location of dikes too small to be mappable features were imported into ArcView from a Microsoft Access database using GPS locations. Surficial geology was plotted on mylar-covered air photos and transferred to stable mylar with a 1:63,360 scale USGS topographic base. Surficial geology was digitized and imported into Arc/Info version 7.0.4 for coding of shapes and lines. Bedrock and surficial geology sets were merged and "windows" were made within surficial units to allow exposure of outcrop and "rubcrop" areas on comprehensive geologic map.

    Data sources used in this process:

    • Foster, 1969
    • Newberry and others, 1988
    • DGGS and others, 1999
    • Szumigala and others, 2000
    • Werdon and others, 2000

    Date: 2000 (process 6 of 7)
    Geologic map compilation- Surficial geologic map was compiled using field notes from fieldwork process step (above), analytical results from laboratory data compilation process step (above), and all known geologic data from previous work in quadrangle. The main sources of existing data include Yeend (1996) and Naeser and others (1982). Geologic map contacts were delineated by photo interpretation of 1:50,000-scale color-infrared aerial photographs onto clear acetate overlays. The contacts were transferred from the overlays onto paper USGS 1:63,360 topographic base maps using a zoom transfer scope, and the contacts were then digitized using ArcEdit. Line work was edited using ArcEdit, and polygon topology generated and unit designations assigned using ArcInfo and ArcEdit.

    Data sources used in this process:

    • Naeser and others, 1982
    • Yeend, 1996

    Date: 2000 (process 7 of 7)
    Geologic map compilation- Comprehensive geologic map was generated using separate GIS coverages of surficial and bedrock geology. The polygon and line coverages were combined using the Arc "union" and "intersect" operations to generate comprehensive geologic coverages in which all areas of exposed bedrock depicted in the surficial coverages are coded as the appropriate bedrock units, as well as coding all bedrock contacts as exposed or buried by surficial deposits.

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

    Szumigala, D.J., Newberry, R.J., Werdon, M.B., Finseth, B.A., Pinney, D.S., and Flynn, R.C., 200004, Major-oxide, minor-oxide, trace-element, and geochemical data from rocks collected in a portion of the Fortymile mining district, Alaska, 1999: Raw Data File RDF 2000-1, State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys, Fairbanks, AK.

    Online Links:

    Other_Citation_Details: 24 p., 2 sheets, scale 1:63,360
    Werdon, M.B., Szumigala, D.J., Newberry, R.J., Grady, J.C., and Munley, W.C., 2000, Major oxide, minor oxide, trace element, rare-earth element, and geochemical data from rocks collected in Eagle and Tanacross quadrangles, Alaska in 2000: Raw Data File RDF 2000-4, State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys, Fairbanks, AK.

    Online Links:

    Other_Citation_Details: 29 p., 3 sheets, scale 1:63,360
    Alaska Division of Geological & Geophysical Surveys, Geoterrex-Dighem, and Stevens Exploration Inc. Staff, 199901, Profile and gridded data and section lines of 1998 geophysical survey data for part of the Fortymile mining district, Alaska, southern Eagle and northern Tanacross quadrangles: Public Data File PDF 99-9, State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys, Fairbanks, AK.

    Online Links:

    Other_Citation_Details: 2 CD-ROMs
    Burns, L.E., and Liss, S.A., 199901, Portfolio of aeromagnetic and resistivity maps of part of the Fortymile mining district, Alaska, southern Eagle and northern Tanacross quadrangles: Public Data File PDF 99-6, State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys, Fairbanks, AK.

    Online Links:

    Other_Citation_Details: 20 p., 1 sheet
    Pritchard, R.A., 199905, Project report of the 1998 geophysical survey data for of part of the Fortymile mining district, Alaska, southern Eagle and northern Tanacross quadrangles: Public Data File PDF 99-7, State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys, Fairbanks, AK.

    Online Links:

    Other_Citation_Details: 162 p., 2 sheets, scale 1:63,360
    Werdon, M.B., Newberry, R.J., and Szumigala, D.J., 200105, Geologic Map of the Eagle A-2 Quadrangle, Fortymile mining district, Alaska 2001: Preliminary Interpretive Report PIR 2001-3B, State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys, Fairbanks, AK.

    Online Links:

    Other_Citation_Details: 1 sheet, scale 1:63,360
    Pinney, D.S., 200105, Surficial-geologic Map of the Eagle A-2 Quadrangle, Fortymile mining district, Alaska 2001: Preliminary Interpretive Report PIR 2001-3C, State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys, Fairbanks, AK.

    Online Links:

    Other_Citation_Details: 1 sheet, scale 1:63,360
    Pinney, D.S., 200105, Engineering-geologic Map of the Eagle A-2 Quadrangle, Fortymile mining district, Alaska 2001: Preliminary Interpretive Report PIR 2001-3D, State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys, Fairbanks, AK.

    Online Links:

    Other_Citation_Details: 1 sheet, scale 1:63,360
    Yeend, Warren, 1996, Gold placers of the historical Fortymile River region, Alaska: U.S. Geological Survey Bulletin 2125, United States Government Printing Office, Washington D.C., Maryland.

    Other_Citation_Details: 74 p., 1 sheet


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

  1. How well have the observations been checked?

    Geospatial data were digitized from mylar and paper geologic compilations. This compilation for the surficial-geologic information was done on a paper map of the USGS topographic base for each of the 1:63,360 scale USGS topographic bases included in the map area. Bedrock geologic information was compiled on stable mylar with abundant control points at 1:50,000 scale that was scanned and co-registered in ArcView GIS Version 3.1? to a 1:63,360-scale USGS topographic base. Geologic data included in the compilation are the field maps and notes from this project as well as data from other sources as noted in the "Sources Cited" section.

  2. How accurate are the geographic locations?

    Surficial mappers recorded observations on 1:50,000 scale (nominal) color-infrared aerial photographs and 1:63,360 scale topographic base maps.

  3. How accurate are the heights or depths?

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

    This data set includes geospatial information about geologic units, age and field sample locations, structural features, structural measurements, pingo and dike locations.

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

    Polygon topology present. Polygon topology present on appropriate data; others are line, point, or annotation data and do not require topologic relationships.


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
    Natural Resource Technician
    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?

    Preliminary Interpretive Report 2001-3A

  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?

    Please check the MapInfo web site (<http://www.mapinfo.com/>) for the latest documentation on importing ESRI shape files.


Who wrote the metadata?

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

907-451-5039 (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)


Generated by mp version 2.9.6 on Tue May 06 14:29:35 2008