Identification_Information:
  Citation:
    Citation_Information:
      Originator: Truskowski, C.M.
      Originator: Heizler, M.T.
      Originator: Naibert, T.J.
      Originator: Newberry, R.J.
      Originator: Twelker, Evan
      Originator: Szumigala, D.J.
      Publication_Date: 2025
      Title: 40Ar/39Ar geochronology data from the Big Delta, Eagle, and Mount Hayes quadrangles, Alaska
      Geospatial_Data_Presentation_Form: csv
      Series_Information:
        Series_Name: Raw Data File
        Issue_Identification: RDF 2025-11
      Publication_Information:
        Publication_Place: Fairbanks, Alaska, United States
        Publisher: Alaska Division of Geological & Geophysical Surveys
      Other_Citation_Details: 21 p.
      Online_Linkage: https://doi.org/10.14509/31534
  Description:
    Abstract: 40Ar/39Ar geochronology data from the Big Delta, Eagle, and Mount Hayes quadrangles, Alaska, Raw Data File 2025-11, presents 40Ar/39Ar geochronological results from samples collected during 1:100,000-scale geologic mapping across approximately 3,100 mi² (8,000 km²) in the Big Delta, Eagle, and Mt. Hayes quadrangles, an area known for gold (Au) mineralization. A total of twenty-four 40Ar/39Ar ages are reported, including three crystallization ages from intrusive rocks, two ages from mineralized veins, one age from a skarn, and eighteen metamorphic cooling ages, comprising six from the Yukon-Tanana Terrane and twelve from parautochthonous North America. These samples were analyzed to refine our understanding of igneous rock crystallization ages, metamorphic rock exhumation history, and the timing of mineralization. These data and report are available from the DGGS website: http://doi.org/10.14509/31534.
    Purpose: The Mount Harper project area contains known gold (Au) mineralization, which has recently been explored in the Richardson mining district - including the Sam Project, the nearby Democrat Lode, and associated prospects - as well as in the Goodpaster mining district at the LMS and Healy intrusion-related gold prospects. The area also hosts a cluster of molybdenum (Mo) and tungsten (W) prospects, including Mo and W skarns. Ultramafic rocks are present in the South Fork Goodpaster and Volkmar River drainages, where their potential to host platinum group elements (PGE), chrome (Cr), cobalt (Co), and nickel (Ni) resources remains poorly understood. These geochronological ages provide further insight into the crystallization history of igneous rocks, the exhumation of metamorphic rocks, and the timing of mineralization.
    Supplemental_Information: >data:    Identification numbers, coordinates, sample descriptions, and summary ages of each sample; power output levels and resultant measurements from each sample run; and an index of the contents, format, and structure of the data.
  Time_Period_of_Content:
    Time_Period_Information:
      Range_of_Dates/Times:
        Beginning_Date: 2022
        Ending_Date: 2025
    Currentness_Reference: ground condition
  Status:
    Progress: Complete
    Maintenance_and_Update_Frequency: None planned
  Spatial_Domain:
    Bounding_Coordinates:
      West_Bounding_Coordinate: -146.190260
      East_Bounding_Coordinate: -143.178860
      North_Bounding_Coordinate: 64.481370
      South_Bounding_Coordinate: 63.844140
  Keywords:
    Theme:
      Theme_Keyword_Thesaurus: ISO 19115 Topic Category
      Theme_Keyword: geoscientificInformation
    Theme:
      Theme_Keyword_Thesaurus: Alaska Division of Geological & Geophysical Surveys
      Theme_Keyword: 40Ar/39Ar
      Theme_Keyword: Age Dates
      Theme_Keyword: Amphibolite
      Theme_Keyword: Analyses
      Theme_Keyword: Analyses and Sampling
      Theme_Keyword: Analytical Lab Results
      Theme_Keyword: Analytical Results
      Theme_Keyword: Ar-Ar
      Theme_Keyword: Batholith
      Theme_Keyword: Bedrock
      Theme_Keyword: Bedrock Geology
      Theme_Keyword: Chlorite
      Theme_Keyword: DGGS
      Theme_Keyword: Economic Geology
      Theme_Keyword: Exploration
      Theme_Keyword: Feldspar
      Theme_Keyword: Gabbro
      Theme_Keyword: Garnet
      Theme_Keyword: Geochronology
      Theme_Keyword: Geologic
      Theme_Keyword: Geological Process
      Theme_Keyword: Geology
      Theme_Keyword: Hornblendite
      Theme_Keyword: Intrusive
      Theme_Keyword: Kyanite
      Theme_Keyword: Molybdenum
      Theme_Keyword: Platinum
      Theme_Keyword: Sulfides
      Theme_Keyword: Tourmaline
      Theme_Keyword: Tungsten
      Theme_Keyword: Ultramafic
    Place:
      Place_Keyword_Thesaurus: Alaska Division of Geological & Geophysical Surveys
      Place_Keyword: Bates Rapids
      Place_Keyword: Big Delta
      Place_Keyword: Bluff Cabin Lake
      Place_Keyword: Boulder Creek
      Place_Keyword: Cottonwood Creek
      Place_Keyword: Delta River
      Place_Keyword: Divide Creek
      Place_Keyword: Eva Creek
      Place_Keyword: Flat Creek
      Place_Keyword: Fourmile Hill
      Place_Keyword: George Creek
      Place_Keyword: Gold Run Creek
      Place_Keyword: Goodpaster River
      Place_Keyword: Healy Lake
      Place_Keyword: Healy River
      Place_Keyword: Hidden Lake
      Place_Keyword: Iron Creek
      Place_Keyword: Joseph Creek
      Place_Keyword: Lenant Creek
      Place_Keyword: Lost Lake
      Place_Keyword: Michigan Creek
      Place_Keyword: Minton Creek
      Place_Keyword: Molly Creek
      Place_Keyword: Monte Cristo Creek
      Place_Keyword: Mount Harper
      Place_Keyword: My Creek
      Place_Keyword: Norvell Creek
      Place_Keyword: Our Creek
      Place_Keyword: Platinum
      Place_Keyword: Progressive Creek
      Place_Keyword: Quartz Lake
      Place_Keyword: Rapid Creek
      Place_Keyword: Salcha River
      Place_Keyword: Sand Creek
      Place_Keyword: Sand Lake
      Place_Keyword: Serpentine Creek
      Place_Keyword: Shaw Creek
      Place_Keyword: Summit
      Place_Keyword: Tanana River
      Place_Keyword: Thompson Lake
      Place_Keyword: Timber
      Place_Keyword: Twentyfive Mile Creek
      Place_Keyword: Uncle Sam Creek
      Place_Keyword: Volkmar Lake
      Place_Keyword: Volkmar River
      Place_Keyword: White Creek
    Stratum:
      Stratum_Keyword_Thesaurus: Alaska Division of Geological & Geophysical Surveys
      Stratum_Keyword: Fortymile River Assemblage
      Stratum_Keyword: Klondike Assemblage
      Stratum_Keyword: Lake George Assemblage
      Stratum_Keyword: Nasina Assemblage
    Temporal:
      Temporal_Keyword_Thesaurus: Walker, J.D., Geissman, J.W., Bowring, S.A, and Babcock, L.E., comp., 2012, Geologic Time Scale v. 4.0: Geological Society of America
      Temporal_Keyword: Early Cretaceous
      Temporal_Keyword: Early Jurassic
      Temporal_Keyword: Late Cretaceous
      Temporal_Keyword: Late Jurassic
      Temporal_Keyword: Late Triassic
      Temporal_Keyword: Middle Jurassic
  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.
  Point_of_Contact:
    Contact_Information:
      Contact_Organization_Primary:
        Contact_Organization: Alaska Division of Geological & Geophysical Surveys
      Contact_Position: Metadata Manager
      Contact_Address:
        Address_Type: mailing and physical
        Address: 3354 College Road
        City: Fairbanks
        State_or_Province: AK
        Postal_Code: 99709-3707
        Country: USA
      Contact_Voice_Telephone: (907)451-5020
      Contact_Facsimile_Telephone: (907)451-5050
      Contact_Electronic_Mail_Address: 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.
  Data_Set_Credit: Sample collection and analyses for the Mount Harper-Richardson project was jointly funded by the State of Alaska and the U.S. Geological Survey's Earth Mapping Resources Initiative (Earth MRI) through cooperative agreement G22AC00288. We thank Peter Grieve and Koza Limited for the drill core sample from Naosi. The views and conclusions contained in this document are those of the authors and should not be interpreted as representing the opinions or policies of the U.S. Geological Survey. Mention of trade names or commercial products does not constitute their endorsement by the U.S. Geological Survey.
  Cross_Reference:
    Citation_Information:
      Originator: Buchanan, J.W.
      Originator: Wypych, Alicja
      Originator: Barrera, M.L.
      Originator: Biegel, J.M.
      Originator: Gavel, M.M.
      Originator: Harvey, D.A.
      Originator: Ketcham, R.A.
      Originator: Muller, I.P.
      Originator: Naibert, T.J.
      Originator: Newberry, R.J.
      Originator: Regan, S.P.
      Originator: Szumigala, D.J.
      Originator: Twelker, Evan
      Originator: Wildland, A.D.
      Publication_Date: 2025
      Title: Geochemical data from samples collected in 2023 for the Chena and Mount Harper projects, Big Delta, Circle, Fairbanks, and Eagle quadrangles, Alaska
      Series_Information:
        Series_Name: Raw Data File
        Issue_Identification: RDF 2024-2
      Publication_Information:
        Publication_Place: Fairbanks, Alaska, United States
        Publisher: Alaska Division of Geological & Geophysical Surveys
      Other_Citation_Details: 5 p
      Online_Linkage: https://doi.org/10.14509/31123
  Cross_Reference:
    Citation_Information:
      Originator: Gavel, M.M.
      Originator: Twelker, Evan
      Originator: Wypych, Alicja
      Originator: Naibert, T.J.
      Originator: Newberry, R.J.
      Originator: Szumigala, D.J.
      Originator: Wildland, A.D.
      Originator: Barrera, M.L.
      Originator: Biegel, J.N.
      Originator: Harvey, D.A.
      Originator: Ketcham, R.A.
      Originator: Muller, I.P.
      Originator: Regan, S.P.
      Publication_Date: 2023
      Title: Field station locations and magnetic susceptibility data for the Chena-Pogo and Mount Harper projects, Big Delta and Circle quadrangles, Alaska, collected June-September 2023
      Series_Information:
        Series_Name: Raw Data File
        Issue_Identification: RDF 2023-27
      Publication_Information:
        Publication_Place: Fairbanks, Alaska, United States
        Publisher: Alaska Division of Geological & Geophysical Surveys
      Other_Citation_Details: 3 p
      Online_Linkage: https://doi.org/10.14509/31096
  Cross_Reference:
    Citation_Information:
      Originator: Gavel, M.M.
      Originator: Twelker, Evan
      Originator: Wypych, Alicja
      Originator: Naibert, T.J.
      Originator: Newberry, R.J.
      Originator: Szumigala, D.J.
      Originator: Wildland, A.D.
      Originator: Barrera, M.L.
      Originator: Blackwell, N.J.
      Originator: Fessenden, S.N.
      Originator: Harvey, D.A.
      Originator: Muller, I.P.
      Publication_Date: 2023
      Title: Field station locations and magnetic susceptibility data collected in 2022 for the Mount Harper project, Eagle, Big Delta, and Mount Hayes quadrangles, Alaska
      Series_Information:
        Series_Name: Raw Data File
        Issue_Identification: RDF 2023-6
      Publication_Information:
        Publication_Place: Fairbanks, Alaska, United States
        Publisher: Alaska Division of Geological & Geophysical Surveys
      Other_Citation_Details: 3 p
      Online_Linkage: https://doi.org/10.14509/30963
  Cross_Reference:
    Citation_Information:
      Originator: Wypych, Alicja
      Originator: Twelker, Evan
      Originator: Naibert, T.J.
      Originator: Gavel, M.M.
      Originator: Newberry, R.J.
      Originator: Szumigala, D.J.
      Originator: Wildland, A.D.
      Originator: Barrera, M.L.
      Originator: Harvey, D.A.
      Originator: Muller, I.P.
      Originator: Fessenden, S.N.
      Originator: Blackwell, N.J.
      Publication_Date: 2023
      Title: Geochemical data from samples collected in 2022 for the Mount Harper geologic mapping project, Big Delta, Mount Hayes, and Eagle quadrangles, Alaska
      Series_Information:
        Series_Name: Raw Data File
        Issue_Identification: RDF 2023-24
      Publication_Information:
        Publication_Place: Fairbanks, Alaska, United States
        Publisher: Alaska Division of Geological & Geophysical Surveys
      Other_Citation_Details: 3 p
      Online_Linkage: https://doi.org/10.14509/31089
Data_Quality_Information:
  Attribute_Accuracy:
    Attribute_Accuracy_Report: The accompanying report and data tables provide a comprehensive discussion of processing methods, with errors reported in the tables where applicable. This data is being released as part of the DGGS RDF series, which includes content describing approved techniques and methods for the collection, storage, visualization, analysis, and interpretation of scientific data. While the information has been reviewed by several geologists familiar with the study area, the data and report have not undergone formal review for technical content or conformity to DGGS editorial standards. For inquiries regarding analytical values or procedures, the originating lab is the best point of contact.
  Logical_Consistency_Report: Not applicable
  Completeness_Report: This data release is complete.
  Positional_Accuracy:
    Horizontal_Positional_Accuracy:
      Horizontal_Positional_Accuracy_Report: Location data for field stations were collected using GPS-enabled tablets or smartphones running the Esri Field Maps app. Data were merged into an ArcGIS geodatabase. The devices have a reported error of 10-12 m. Latitude and longitude are reported in the WGS84 datum.
  Lineage:
    Process_Step:
      Process_Description: Sample Collection - Fresh, unweathered samples from surface outcrops or pits dug to expose fragmented bedrock were collected by DGGS field geologists and were selected for dating based on the presence of sufficiently large crystals appropriate for analysis. Sample 22Z405 was collected from unidentified drill core found on the ground near the LMS prospect by David Szumigala, and sample 22MLB313 is drill core from the Naosi deposit at 90.00-91.50 m depth, obtained by Mike Barerra and Evan Twelker. Sample location coordinates (in WGS84 datum) were collected using GPS-enabled field tablets with a typical reported accuracy of +/- 10 meters. We examined samples under a binocular microscope and/or in thin section to select unaltered mineral phases appropriate for analysis.
      Process_Date: 2022
    Process_Step:
      Process_Description: Sample preparation - Twenty-four samples submitted to the New Mexico Geochronological Research Laboratory (NMGRL) in Socorro, New Mexico, yielded acceptable mineral separates for 40Ar/39Ar thermochronology. Muscovite, hornblende, and sericite were separated from rock samples using standard magnetic, heavy liquid, and handpicking procedures. The samples were loaded into machined aluminum discs and irradiated for 20 hours at the USGS reactor in Denver, Colorado, (NM-327) along with the Fish Canyon Tuff sanidine standard (FC-2; assigned age-28.201 Ma; Kuiper and others, 2008) as a neutron flux monitor.
      Process_Date: 2023
    Process_Step:
      Process_Description: Analytical methods - After irradiation, the samples and monitors were analyzed by step-heating with a defocused 810 nm diode laser. The samples were step-heated using between 10 and 18 increments, and most age spectra yielded moderate-quality to complex patterns. Reactive gases were removed by a 45-second reaction with a SAES GP-50 getter at 450 degrees C, and gas was also exposed to a cold finger at -140 degrees C. The samples were analyzed in a Thermo-Fisher Scientific Helix MC-plus mass spectrometer at NMGRL. Total system blanks were 3.5 x 10-17 mol 40Ar, 8 x 10-18 mol 39Ar, 5 x 10-19 mol 38Ar, 3 x 10-18 mol 37Ar, and 5 x 10-19 mol 36Ar. Isotopic ratios were corrected for blank, radioactive decay, and mass discrimination but were not corrected for interfering reactions.
      Process_Date: 2024
Spatial_Data_Organization_Information:
  Direct_Spatial_Reference_Method: point
Spatial_Reference_Information:
  Horizontal_Coordinate_System_Definition:
    Geographic:
      Latitude_Resolution: 0.0000001
      Longitude_Resolution: 0.0000001
      Geographic_Coordinate_Units: decimal degrees
    Geodetic_Model:
      Horizontal_Datum_Name: WGS84
      Ellipsoid_Name: WGS 84
      Semi-major_Axis: 6378137
      Denominator_of_Flattening_Ratio: 298.257223563
Entity_and_Attribute_Information:
  Detailed_Description:
    Entity_Type:
      Entity_Type_Label: rdf2025_011_summary_data.csv, rdf2025_011_step_heating_data_dictionary.csv, rdf2025_011_step_heating_data.csv, df2025_011_summary_data_dictionary.csv
      Entity_Type_Definition: Identification numbers, coordinates, sample descriptions, and summary ages of each sample; power output levels and resultant measurements from each sample run; and an index of the contents, format, and structure of the data.
      Entity_Type_Definition_Source: DGGS, see report for additional detail.
      Entity_Attribute_Layer_Name: data
Distribution_Information:
  Distributor:
    Contact_Information:
      Contact_Organization_Primary:
        Contact_Organization: Alaska Division of Geological & Geophysical Surveys
      Contact_Position: Metadata Manager
      Contact_Address:
        Address_Type: mailing and physical
        Address: 3354 College Road
        City: Fairbanks
        State_or_Province: AK
        Postal_Code: 99709-3707
        Country: USA
      Contact_Voice_Telephone: (907)451-5020
      Contact_Facsimile_Telephone: (907)451-5050
      Contact_Electronic_Mail_Address: 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.
  Resource_Description: RDF 2025-11
  Distribution_Liability: 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.
  Standard_Order_Process:
    Non-digital_Form: DGGS publications are available as free online downloads or you may purchase paper hard-copies or digital files on CD/DVD or other digital storage media by mail, phone, fax, or email from the DGGS Fairbanks office. To purchase this or other printed reports and maps, contact DGGS by phone (907-451-5020), e-mail (dggspubs@alaska.gov), or fax (907-451-5050). Payment accepted: Cash, check, money order, VISA, or MasterCard. Turnaround time is 1-2 weeks unless special arrangements are made and an express fee is paid. Shipping charge will be the actual cost of postage and will be added to the total amount due. Contact us for the exact shipping amount.
    Fees: Contact DGGS for current pricing
  Standard_Order_Process:
    Digital_Form:
      Digital_Transfer_Information:
        Format_Name: csv
        Format_Version_Date: 20250401
        Format_Information_Content: table
      Digital_Transfer_Option:
        Online_Option:
          Computer_Contact_Information:
            Network_Address:
              Network_Resource_Name: https://doi.org/10.14509/31534
    Fees: Free download
Metadata_Reference_Information:
  Metadata_Date: 20250401
  Metadata_Contact:
    Contact_Information:
      Contact_Organization_Primary:
        Contact_Organization: Alaska Division of Geological & Geophysical Surveys
        Contact_Person: Simone Montayne
      Contact_Position: Metadata Manager
      Contact_Address:
        Address_Type: mailing and physical
        Address: 3354 College Road
        City: Fairbanks
        State_or_Province: AK
        Postal_Code: 99709-3707
        Country: USA
      Contact_Voice_Telephone: (907)451-5020
      Contact_Facsimile_Telephone: (907)451-5050
      Contact_Electronic_Mail_Address: dggspubs@alaska.gov
      Hours_of_Service: 8 am to 4:30 pm, Monday through Friday, except State holidays
  Metadata_Standard_Name: FGDC Content Standard for Digital Geospatial Metadata
  Metadata_Standard_Version: FGDC-STD-001-1998
  Metadata_Use_Constraints: If the user has modified the data in any way they are obligated to describe the types of modifications they have performed in the supporting metadata file. User specifically agrees not to imply that changes they made were approved by the Alaska Department of Natural Resources or Division of Geological & Geophysical Surveys.
  Metadata_Extensions:
    Online_Linkage: https://dggs.alaska.gov/metadata/dggs.ext
    Profile_Name: dggs metadata extensions