Bedrock geologic map of the northern Fairbanks mining district, Circle Quadrangle, Alaska

Metadata also available as - [Parseable text] - [XML]

Frequently anticipated questions:

What does this data set describe?

Title:
Bedrock geologic map of the northern Fairbanks mining district, Circle Quadrangle, Alaska
Abstract:
Bedrock geologic map of the northern Fairbanks mining district, Circle Quadrangle, Alaska, Preliminary Interpretive Report 2022-2, presents a 1:50,000-scale bedrock geologic map of the northern Fairbanks mining district, covering parts of the Circle A-4, A-5, B-4, and B-5 quadrangles. The 188-square-mile study area is 55 direct miles northeast of Fairbanks, straddling the Steese Highway between miles 66 and 85. The field area is coincident with the northern tip of the Fairbanks mining district, Alaska's largest historic producer at just less than 17 million troy ounces of gold. This area is within the northeast-oriented trend between plutonic-related gold mineralization in the central Fairbanks mining district and placer gold deposits in the northwest Circle mining district. During June 2007, personnel from the Alaska Division of Geological & Geophysical Surveys (DGGS) and the University of Alaska Fairbanks spent approximately 189 person-days conducting fieldwork in the northeast Fairbanks area. Geologic units are defined by field observations and analysis of samples collected at more than 2,222 stations. Unit descriptions are also based on the petrographic examination and modal analysis of 301 thin sections (this study), 116 thin sections collected in the Circle Quadrangle by the U.S. Geological Survey from 1979-1981, and 26 thin sections from the 1986 Lime Peak-Mt. Prindle project. Metamorphic rocks and younger, unmetamorphosed igneous rocks were primarily defined by chemical composition, examination of hand samples, and petrography. Forty-four rock samples were analyzed for major- and minor-oxide by a commercial analytical laboratory and trace elements by the University of Alaska Fairbanks. These data are used to suggest possible protoliths of metamorphosed and altered rocks, identify types of alteration, and assign trace element-indicated tectonic settings to igneous and metamafic rocks. Non-carbonate carbon in 16 samples was measured by a commercial analytical laboratory. Garnet-biotite geothermometry and garnet-plagioclase-muscovite-biotite equilibria geobarometry were conducted on 16 samples to assess the metamorphic history of the units. Five 40Ar/39Ar ages were used to constrain the timing of igneous events, mineralization, and metamorphism in the northeast Fairbanks area. One U-Pb detrital zircon age provides a maximum age of the metamorphosed sedimentary rocks and for regional unit correlations. Total field magnetic and electromagnetic geophysical data aided our bedrock mapping, especially in areas covered by vegetation and unconsolidated Quaternary deposits. The complete report, geodatabase, and ESRI fonts and style files are available from the DGGS website: http://doi.org/10.14509/30891.
Supplemental_Information:
This geodatabase is organized according to the AK GeMS mapping schema Hendricks, M.D., Ekberg, P.G., Athey, J.E., Wyatt, W.C., Willingham, A.L., and Naibert, T.J., 2021, AK GeMS data dictionary: A description of the Alaska geologic mapping schema: Alaska Division of Geological & Geophysical Surveys Miscellaneous Publication 170, 10 p. https://doi.org/10.14509/30669. The distribution package includes ESRI fonts and style files, along with usage instructions. Further documentation of the symbology is provided by Ekberg, P.G., Hendricks, M.D., and Athey, J.E., 2021, AK GeMS symbology: A description of the AK GeMS style file: Alaska Division of Geological & Geophysical Surveys Miscellaneous Publication 169, 7 p. https://doi.org/10.14509/30584
  1. How might this data set be cited?
    Athey, J.E., Freeman, L.K., Newberry, R.J., Werdon, M.B., Szumigala, D.J., and Lessard, R.R., 2022, Bedrock geologic map of the northern Fairbanks mining district, Circle Quadrangle, Alaska: Preliminary Interpretive Report PIR 2022-2, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 24 p., 1 sheet, scale 1:50,000
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -146.474345
    East_Bounding_Coordinate: -145.982025
    North_Bounding_Coordinate: 65.411456
    South_Bounding_Coordinate: 65.207853
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 2007
    Ending_Date: 2022
    Currentness_Reference:
    ground condition
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: geodatabase
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      This is a vector data set.
    2. What coordinate system is used to represent geographic features?
      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:
      UTM_Zone_Number: 6
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.999600
      Longitude_of_Central_Meridian: -147
      Latitude_of_Projection_Origin: 0
      False_Easting: 500000.000000
      False_Northing: 0
      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest .00000001
      Ordinates (y-coordinates) are specified to the nearest .00000001
      Planar coordinates are specified in Meters
      The horizontal datum used is NAD27.
      The ellipsoid used is Clarke 1866.
      The semi-major axis of the ellipsoid used is 6378206.4.
      The flattening of the ellipsoid used is 1/294.9786982.
  7. How does the data set describe geographic features?
    ne_fairbanks_ak_gems_db_pkg
    Geodatabase, layer files, style files, and fonts (Source: DGGS)
    ne_fairbanks_gems_db_pkg
    Geodatabase, layer files, style files, and fonts (Source: DGGS)
    ne_fairbanks_gems_shapefile_pkg
    Shapefiles and open data files (Source: DGGS)

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 State of Alaska's Airborne Geophysical/Geological Mineral Inventory (AGGMI) program, a special multi-year investment by the state to expand Alaska's geologic and mineral resources knowledge base, catalyze future private-sector mineral exploration and development, and guide state planning. AGGMI was funded by the Alaska State Legislature and managed by the State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys. This geologic map was partly funded by the USGS National Cooperative Geologic Mapping Program under STATEMAP award number 07HQAG0076, 2007 (fieldwork) and G20AC00367, 2020 (GeMS conversion). The State of Alaska General Fund provided additional funding. 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?
    Alaska Division of Geological & Geophysical Surveys
    Metadata Manager
    3354 College Road
    Fairbanks, AK
    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 website (https://www.dggs.alaska.gov) for the latest information on available data. Please contact us using the e-mail address provided above when possible.

Why was the data set created?

The bedrock geologic interpretations and investigation of the northern Fairbanks mining district, Alaska, were implemented as part of an ongoing DGGS program to provide geologic mapping and supporting geochemical, petrologic, and geochronologic data to foster a better understanding of Alaska's geology and mineral potential.

How was the data set created?

  1. From what previous works were the data drawn?
    Athey, J.E. and others, 2008 (source 1 of 6)
    Athey, J.E., Freeman, L.K., Werdon, M.B., Szumigala, D.J., Lessard, R.R., Newberry, R.J., Hansen, S.E., and Jing, L., 2008, Major-oxide, minor-oxide, and trace-element geochemical data from rocks and stream sediments collected in the northern Fairbanks mining district, Circle Quadrangle, Alaska in 2007: Raw Data File RDF 2008-1 v. 1.0.1, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 41 p
    Type_of_Source_Media: paper
    Source_Contribution: Geologic mapping
    Burns, L.E. and others, 2019 (source 2 of 6)
    Burns, L.E., Graham, G.R.C., Barefoot, J.D., Surveys, Fugro Airborne, and Stevens Exploration Management Corp., 2019, Northeast Fairbanks electromagnetic and magnetic airborne geophysical survey data compilation: Geophysical Report GPR 2018-11, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 12 p
    Type_of_Source_Media: paper
    Source_Contribution: Geologic mapping
    Ekberg, P.G. and others, 2021 (source 3 of 6)
    Ekberg, P.G., Hendricks, M.D., and Athey, J.E., 2021, AK GeMS symbology: A description of the AK GeMS style file: Miscellaneous Publication MP 169, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 7 p
    Type_of_Source_Media: paper
    Source_Contribution: GIS analysis and digital cartography
    Hendricks, M.D. and others, 2021 (source 4 of 6)
    Hendricks, M.D., Ekberg, P.G., Athey, J.E., Wyatt, W.C., Willingham, A.L., and Naibert, T.J., 2021, AK GeMS data dictionary: A description of the Alaska geologic mapping schema: Miscellaneous Publication MP 170, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 10 p
    Type_of_Source_Media: paper
    Source_Contribution: GIS analysis and digital cartography
    Smith, T.E. and others, 1987 (source 5 of 6)
    Smith, T.E., Pessel, G.H., and Wiltse, M.A., 1987, Mineral assessment of the Lime Peak-Mt. Prindle area, Alaska: Miscellaneous Publication MP 29, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 712 p., 13 sheets, scale 1:63,360
    Type_of_Source_Media: paper
    Source_Scale_Denominator: 63360
    Source_Contribution: Geologic mapping
    U.S. Geological Survey National Cooperative Geologic Mapping Program, 2020 (source 6 of 6)
    U.S. Geological Survey National Cooperative Geologic Mapping Program, 2020, GeMS (Geologic Map Schema) - A standard format for the digital publication of geologic maps: Techniques and Methods TM 11-B10, U.S. Geological Survey, United States.

    Online Links:

    Other_Citation_Details: 1 p
    Type_of_Source_Media: paper
    Source_Contribution: GIS analysis and digital cartography
  2. How were the data generated, processed, and modified?
    Date: 2007 (process 1 of 2)
    Geologic mapping - During June 2007, personnel from the Alaska Division of Geological & Geophysical Surveys (DGGS) and the University of Alaska Fairbanks spent approximately 189 person-days conducting field work in the northeast Fairbanks area. The study area is located within the Yukon-Tanana Uplands, and elevations in the map area range from 1,417 to 4,184 feet. Topography consists of moderate- to steep-sided ridges and domes vegetated with tundra, spruce, aspen, poplar, alder, and willow. About half of the study area was partially burned in the 2004 Boundary wildfire, and exposed bedrock was discovered during 2007 fieldwork in places that were previously heavily vegetated. Natural outcrops commonly occur along hilltops, steep slopes, and in incised stream valleys. The map area covers the central portion of the Northeast Fairbanks airborne geophysical survey (Burns and others, 2006; superseded by Burns and others, 2019a). Total field magnetic and electromagnetic geophysical data aided our bedrock mapping, especially in areas covered by vegetation and unconsolidated Quaternary deposits. Geologic units are defined by field observations and analysis of samples collected at more than 2,222 stations. Unit descriptions are also based on the petrographic examination and modal analysis of 301 thin sections (this study), 116 thin sections collected in the Circle Quadrangle by the U.S. Geological Survey from 1979-1981, and 26 thin sections from the 1986 Lime Peak-Mt. Prindle project (Smith and others, 1987). Metamorphic rocks and younger, unmetamorphosed igneous rocks were primarily defined by chemical composition, examination of hand samples, and petrography. Forty-four rock samples were analyzed for major- and minor-oxide by a commercial analytical laboratory, and trace elements by the University of Alaska Fairbanks. These data are used to suggest possible protoliths of metamorphosed and altered rocks, identify types of alteration, and assign trace element-indicated tectonic settings to igneous and metamafic rocks. Non-carbonate carbon in 16 samples was measured by a commercial analytical laboratory. Garnet-biotite geothermometry and garnet-plagioclase-muscovite-biotite equilibria geobarometry were conducted on 16 samples to assess the metamorphic history of the units. Five 40Ar/39Ar ages were used to constrain timing of igneous events, mineralization, and metamorphism in the northeast Fairbanks area. One U-Pb detrital zircon age provides a maximum age of the metamorphosed sedimentary rocks and for regional unit correlations. The conceptual framework for the geology incorporates key ideas from preexisting literature with new data and interpretations developed from field mapping and analytical findings. The accompanying map or report provides a comprehensive bibliographic reference list of prior work used to identify and delineate rock units and structural elements. Data sources used in this process:
    • Athey, J.E. and others, 2008
    • Burns, L.E. and others, 2019
    • Smith, T.E. and others, 1987
    Date: 2022 (process 2 of 2)
    GIS analysis and digital cartography - This data distribution package's geologic and geographic features were organized and attributed according to the AK GeMS geologic mapping schema. The data were programmatically transformed to provide download options in three formats: (1) an AK GeMS data package that includes the complete AK GeMS database and associated files, (2) a GeMS data package that is a conversion of the AK GeMS database into the base GeMS standard published by the USGS, and (3) a shapefile data package that includes two simple shapefile representations of the data. Data sources used in this process:
    • Ekberg, P.G. and others, 2021
    • Hendricks, M.D. and others, 2021
    • U.S. Geological Survey National Cooperative Geologic Mapping Program, 2020
  3. What similar or related data should the user be aware of?

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

  1. How well have the observations been checked?
    Attribute fields within each feature class are populated using the map symbology and corresponding applicable values from the GeMS and AK GeMS specifications. When known, certainty in attribute interpretation is indicated in the relevant fields. Attribute accuracy varies throughout the map and is scale-dependent.
  2. How accurate are the geographic locations?
    Certainty in feature boundaries or location varies throughout the map. Data fields within each feature class and the accompanying orientation and location confidence lookup tables record the authors' degree of confidence in the location of applicable features.
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
    This publication is a DGGS Preliminary Interpretive Report (PIR). A PIR provides timely release maps and reports with a preliminary interpretation of geology or analytical data. Several scientists familiar with the geology of map area have reviewed this publication for technical content.
  5. How consistent are the relationships among the observations, including topology?
    All polygon features were topologically validated according to the AK GeMS geologic mapping schema specifications.

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 is 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. The 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. The State of Alaska makes no express or implied warranties (including warranties for merchantability and fitness) with respect to the character, functions, or capabilities of the electronic data 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 or any failure thereof or otherwise. In no event will the State of Alaska's liability to the Requestor or anyone else exceed the fee paid for the electronic service or product.
  1. Who distributes the data set? (Distributor 1 of 1)
    Alaska Division of Geological & Geophysical Surveys
    Metadata Manager
    3354 College Road
    Fairbanks, AK
    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 website (https://www.dggs.alaska.gov) 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? PIR 2022-2
  3. What legal disclaimers am I supposed to read?
    The State of Alaska makes no expressed or implied warranties (including warranties for merchantability and fitness) with respect to the character, functions, or capabilities of the electronic data 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 or any failure thereof or otherwise. In no event will the State of Alaska's liability to the Requestor or anyone else exceed the fee paid for the electronic service or product.
  4. How can I download or order the data?

Who wrote the metadata?

Dates:
Last modified: 29-Aug-2022
Metadata author:
Alaska Division of Geological & Geophysical Surveys
Attn: Simone Montayne
Metadata Manager
3354 College Road
Fairbanks, AK
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
Metadata standard:
FGDC Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
Metadata extensions used:
Generated by mp version 2.9.50 on Mon Aug 29 16:24:45 2022