Preliminary geologic map and data tables of the Ophir C-1 and western Medfra C-6 quadrangles, Alaska

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Frequently anticipated questions:


What does this data set describe?

Title:
Preliminary geologic map and data tables of the Ophir C-1 and western Medfra C-6 quadrangles, Alaska
Abstract:
Preliminary geologic map and data tables of the Ophir C-1 and western Medfra C-6 quadrangles, Alaska, Public Data File 97-46, presents preliminary geologic findings from 1:63,360-scale mapping conducted by DGGS in May and June 1996 across the Ophir C-1 and western Medfra C-6 quadrangles in western Alaska. The study documents bedrock units from the Ruby and Innoko terranes, Cretaceous flysch, and the Cripple Creek Mountains volcano-plutonic complex, along with 17 unconsolidated surficial deposits. DGGS identified complex structural relationships, including multiple folding events and fault systems, and began radiometric dating to refine the geologic timeline. Economic geology highlights include placer gold production and mineralized zones in the Cripple Creek Mountains, where gold-antimony veins and breccia zones align with key fault intersections. The complete report, geodatabase, and ESRI fonts and style files are available from the Alaska Division of Geological & Geophysical Surveys website: http://doi.org/10.14509/1811.
Supplemental_Information:
This geodatabase is organized according to the AK GeMS mapping schema Hendricks, M.D., Macpherson, A.E., Athey, J.E., Wyatt, W.C., Montayne, Simone, Buchanan, Wes, Rivera, P.G., and Steinleitner, A.M., 2024, AK GeMS data dictionary: A description of the Alaska geologic mapping schema: Alaska Division of Geological & Geophysical Surveys Miscellaneous Publication 170 v. 2, 13 p. https://doi.org/10.14509/31172. 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?
    Bundtzen, T.K., Pinney, D.S., and Laird, G.M., 1997, Preliminary geologic map and data tables of the Ophir C-1 and western Medfra C-6 quadrangles, Alaska: Public Data File PDF 97-46, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 11 p., 1 sheet, scale 1:63,360
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -156.522257
    East_Bounding_Coordinate: -155.765181
    North_Bounding_Coordinate: 63.763486
    South_Bounding_Coordinate: 63.474946
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 1996
    Ending_Date: 2025
    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: 4
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.999600
      Longitude_of_Central_Meridian: -159
      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?
    ophir_c1_medfra_c6_quads_prelim_geo_ak_gems_db_pkg
    Geodatabase, layer files, style files, and fonts (Source: DGGS and USGS)
    ophir_c1_medfra_c6_quads_prelim_geo_gems_db_pkg
    Geodatabase, layer files, style files, and fonts (Source: DGGS and USGS)
    ophir_c1_medfra_c6_quads_prelim_geo_gems_geopackage
    SQLite Database file (Source: DGGS and USGS)
    ophir_c1_medfra_c6_quads_prelim_geo_gems_shapefile_pkg
    Shapefiles and open data files (Source: DGGS and USGS)

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?
    Stephanie Foggia ably assisted all three geologists during the numerous field traverses completed in the study area. We especially thank the employees of Rosander Mining Company for providing warm hospitality and useful geologic discussions during our investigations. James Barker from Northwest Land Resources Inc. provided stimulating discussions about the region's polymetallic lode and placer gold deposits. Kinney Engineering, LLC staff used scanned and georeferenced paper maps to digitize geologic features into an AK GeMS database. Chris Wyatt conducted quality control of this digitizing work and completed the creation of the AK GeMS database. Ally M. Steinleitner implemented final database quality control and packaging. This geologic map (or report or conversion or product, etc.) was funded by the USGS National Cooperative Geologic Mapping Program under STATEMAP award number G23AC00584, 2023, and the State of Alaska General Fund. 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?

DGGS conducted geologic mapping in the Ophir C-1 and western Medfra C-6 quadrangles of western Alaska to improve understanding of the region's mineral resource potential. By documenting bedrock units, structural features, and mineralized zones, they aimed to identify geologic controls on gold-bearing deposits and support future exploration in the Innoko Mining District.

How was the data set created?

  1. From what previous works were the data drawn?
    Ekberg, P.G. and others, 2021 (source 1 of 3)
    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 2 of 3)
    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
    U.S. Geological Survey National Cooperative Geologic Mapping Program, 2020 (source 3 of 3)
    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: 1996 (process 1 of 2)
    Geologic mapping - DGGS geologists conducted 1:63,360-scale geologic mapping in May and June of 1996 across the Ophir C-1 and western Medfra C-6 quadrangles in western Alaska. They described map units, identified fossils, and analyzed geochemical and mineralogical data from 25 mineralized zones and prospects. They examined bedrock packages, documented surficial deposits, and initiated radiometric dating. They also recorded structural features, including folds and faults, to support geologic interpretation.
    Date: 2025 (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 legacy 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?
    Reger, R.D., Campbell, K.M., Stevens, D.S.P., and Smith, R.L., 2003, Survey of geology, geologic materials, and geologic hazards in proposed access corridors in the Ophir Quadrangle, Alaska: Miscellaneous Publication MP 100, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 5 sheets, scale 1:250,000

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 Public Data File (PDF). The objective of this series, published from 1983 through 1999, was to make project and field data available to the public as soon as possible. PDFs were not reviewed or edited.
  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? PDF 97-46
  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: 02-Oct-2025
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 Thu Oct 02 11:48:53 2025