Identification_Information: Citation: Citation_Information: Originator: Layer, P.W. Originator: Drake, Jeffrey Originator: Athey, J.E. Originator: Naibert, T.J. Publication_Date: 2025 Title: 40Ar/39Ar data from the northern Fairbanks mining district, Circle Quadrangle, Alaska Geospatial_Data_Presentation_Form: csv Series_Information: Series_Name: Raw Data File Issue_Identification: RDF 2025-1 Publication_Information: Publication_Place: Fairbanks, Alaska, United States Publisher: Alaska Division of Geological & Geophysical Surveys Other_Citation_Details: 8 p. Online_Linkage: https://doi.org/10.14509/31472 Description: Abstract: 40Ar/39Ar data from the northern Fairbanks mining district, Circle Quadrangle, Alaska, Raw Data File 2025-1, presents 40Ar/39Ar step-heating geochronology results for igneous and metamorphic rocks from the Alaska Division of Geological & Geophysical Surveys' (DGGS) geologic mapping project in the northern Fairbanks mining district, covering parts of the Circle A-4, A-5, B-4, and B-5 quadrangles, Alaska. Field samples were collected by the DGGS Mineral Resources Section during a detailed geologic mapping campaign in June 2007. In addition to analytical data compiled in the geologic map for this area, other DGGS publications supporting geologic mapping in the northern Fairbanks mining district include geophysical data, geochemical data, and a planned U-Pb detrital zircon age report. The northern Fairbanks mining district map area lies within the Yukon-Tanana Upland in rocks that we interpret to correlate with the Cambrian to Late Proterozoic Fairbanks schist and the Wickersham Grit unit. These rocks are intruded by several phases of plutonism, of which two occur in the map area: Tertiary and Cretaceous plugs, dikes, and sills with characteristic geochemical signatures. The Cretaceous intrusions are regionally associated with placer- and lode-gold mines and occurrences. The age data in this report constrain the crystallization ages of igneous rocks, the potential timing of mineralization, and the cooling histories of metamorphic rocks in the map area. These data and report are available from the DGGS website: http://doi.org/10.14509/31472. Purpose: This work furthers our understanding of potential mineral resources in the Circle A-4, A-5, B-4, and B-5 quadrangles of the northern Fairbanks mining district map area, which lies within Alaska's Yukon-Tanana Upland. 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: 2007 Ending_Date: 2025 Currentness_Reference: ground condition Status: Progress: Complete Maintenance_and_Update_Frequency: None planned Spatial_Domain: Bounding_Coordinates: West_Bounding_Coordinate: -146.450877 East_Bounding_Coordinate: -146.142762 North_Bounding_Coordinate: 65.398043 South_Bounding_Coordinate: 65.226045 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: Arsenopyrite Theme_Keyword: Bedrock Theme_Keyword: Crystals Theme_Keyword: DGGS Theme_Keyword: Exploration Theme_Keyword: Geochronology Theme_Keyword: Geologic Theme_Keyword: Geology Theme_Keyword: Granodiorite Theme_Keyword: Hornblende Theme_Keyword: Mica Theme_Keyword: Mineral Assessment Theme_Keyword: Mineral Composition Theme_Keyword: Mineral Resources Theme_Keyword: Mineralogy Theme_Keyword: Minerals Theme_Keyword: Monzogranite Theme_Keyword: Outcrop Samples Theme_Keyword: Plutons Theme_Keyword: Quartz Theme_Keyword: Sample Location Theme_Keyword: Sericite Theme_Keyword: Syenite Place: Place_Keyword_Thesaurus: Alaska Division of Geological & Geophysical Surveys Place_Keyword: Circle Place_Keyword: Fairbanks Mining District 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: Cenozoic Temporal_Keyword: Cretaceous Temporal_Keyword: Mesozoic Temporal_Keyword: Paleocene Temporal_Keyword: Paleogene 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: The Northern Fairbanks Mining District 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. Fieldwork for the project was also partially funded by the USGS National Cooperative Geologic Mapping Program under STATEMAP award number 07HQAG0076. Additional funding was provided by 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. Cross_Reference: Citation_Information: Originator: Athey, J.E. Originator: Freeman, L.K. Originator: Newberry, R.J. Originator: Werdon, M.B. Originator: Szumigala, D.J. Originator: Lessard, R.R. Publication_Date: 2022 Title: Bedrock geologic map of the northern Fairbanks mining district, Circle Quadrangle, Alaska Series_Information: Series_Name: Preliminary Interpretive Report Issue_Identification: PIR 2022-2 Publication_Information: Publication_Place: Fairbanks, Alaska, United States Publisher: Alaska Division of Geological & Geophysical Surveys Other_Citation_Details: 24 p., 1 sheet, scale 1:50,000 Online_Linkage: https://doi.org/10.14509/30891 Cross_Reference: Citation_Information: Originator: Athey, J.E. Originator: Freeman, L.K. Originator: Werdon, M.B. Originator: Szumigala, D.J. Originator: Lessard, R.R. Originator: Newberry, R.J. Originator: Hansen, S.E. Originator: Jing, Liping Publication_Date: 2008 Title: 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 Series_Information: Series_Name: Raw Data File Issue_Identification: RDF 2008-1 v. 1.0.1 Publication_Information: Publication_Place: Fairbanks, Alaska, United States Publisher: Alaska Division of Geological & Geophysical Surveys Other_Citation_Details: 41 p Online_Linkage: https://doi.org/10.14509/15901 Cross_Reference: Citation_Information: Originator: Burns, L.E. Originator: Graham, G.R.C. Originator: Barefoot, J.D. Originator: Fugro Airborne Surveys Originator: Stevens Exploration Management Corp. Publication_Date: 2019 Title: Northeast Fairbanks electromagnetic and magnetic airborne geophysical survey data compilation Series_Information: Series_Name: Geophysical Report Issue_Identification: GPR 2018-11 Publication_Information: Publication_Place: Fairbanks, Alaska, United States Publisher: Alaska Division of Geological & Geophysical Surveys Other_Citation_Details: 12 p Online_Linkage: https://doi.org/10.14509/30062 Cross_Reference: Citation_Information: Originator: Newberry, R.J. Originator: Bundtzen, T.K. Originator: Clautice, K.H. Originator: Combellick, R.A. Originator: Douglas, Tom Originator: Laird, G.M. Originator: Liss, S.A. Originator: Pinney, D.S. Originator: Reifenstuhl, R.R. Originator: Solie, D.N. Publication_Date: 1996 Title: Preliminary geologic map of the Fairbanks mining district, Alaska Series_Information: Series_Name: Public Data File Issue_Identification: PDF 96-16 Publication_Information: Publication_Place: Fairbanks, Alaska, United States Publisher: Alaska Division of Geological & Geophysical Surveys Other_Citation_Details: 17 p., 2 sheets, scale 1:63,360 Online_Linkage: https://doi.org/10.14509/1740 Data_Quality_Information: Attribute_Accuracy: Attribute_Accuracy_Report: The accompanying report and data tables provide a discussion of processing methods. The tables contain measured values, calculated values, testing parameters, and statistical errors reported by the laboratory. Summary values are also included where applicable. Analytical results may include laboratory interpretations when an interpretive review is necessary for generating usable output. While the reports and data have been evaluated by project staff for general readability and logical consistency, the laboratory data may not have undergone technical peer review. Logical_Consistency_Report: Not applicable Completeness_Report: This data release is complete. Positional_Accuracy: Horizontal_Positional_Accuracy: Horizontal_Positional_Accuracy_Report: Sample location coordinates were obtained using recreational-grade GPS units, with a typical reported accuracy of about 10 meters. Coordinates are reported using the WGS84 datum. Hand samples and (or) thin sections were examined to select unaltered mineral phases before sample preparation. Lineage: Process_Step: Process_Description: Sample collection - Samples from surface outcrops were collected by DGGS field geologists and were selected for dating based on the priority of information needed, presence of sufficiently large crystals appropriate for dating, and minimal weathering. Sample location coordinates were obtained using recreational-grade GPS units, with a typical reported accuracy of about 10 meters. Coordinates are reported using the WGS84 datum. Hand samples and (or) thin sections were examined to select unaltered mineral phases before sample preparation. Process_Date: 2007 Process_Step: Process_Description: Sample preparation - Five rock samples were submitted to the Geochronology Laboratory at the University of Alaska Fairbanks (UAF) for 40Ar/39Ar analysis. The samples were crushed, sieved to either 100-250 or 250-500 micron size fractions, and handpicked for biotite, hornblende, and sericite mineral phases. The monitor mineral MMhb-1 (Samson and Alexander, 1987) with an age of 513.9 Ma (Lanphere and Dalrymple, 2000) was used to monitor neutron flux and calculate the irradiation parameter J. The samples and standards were wrapped in aluminum foil and loaded into aluminum cans of 2.5 cm diameter and 6 cm height. The samples were irradiated in position 5c of the uranium-enriched research reactor at McMaster University in Hamilton, Ontario, Canada, for 20 megawatt-hours. Process_Date: 2008 Process_Step: Process_Description: Analytical methods - Upon their return from the reactor, the samples and monitors were loaded into 2-mm-diameter holes in a copper tray, which was then loaded in an ultra-high-vacuum extraction line. The monitors were fused, and samples heated, using a 6-watt argon-ion laser following the technique described in York and others (1981), Layer and others (1987), and Layer (2000). Argon purification was achieved using a liquid nitrogen cold trap and a SAES Zr-Al getter at 400 degrees C. The samples were analyzed in a VG-3600 mass spectrometer at the Geophysical Institute, University of Alaska Fairbanks. The argon isotopes measured were corrected for system blank and mass discrimination, as well as calcium, potassium, and chlorine interference reactions following procedures outlined in McDougall and Harrison (1999). System blanks generally were 2x10-16 mol 40Ar and 2x10-18 mol 36Ar, which are 10 to 50 times smaller than fraction volumes. Mass discrimination was monitored by running both calibrated air shots and a zero-age glass sample. These measurements were made on a weekly to monthly basis to check for changes in mass discrimination, with no significant variation observed during these intervals. Process_Date: 2008 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: rdf2025-1_ar_ar_step-heating-data.csv, rdf2025-1_ar_ar_summary-data-locations.csv, rdf2025-1_ar_ar_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, UAF 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 2025-1 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: 20250224 Format_Information_Content: table Digital_Transfer_Option: Online_Option: Computer_Contact_Information: Network_Address: Network_Resource_Name: https://doi.org/10.14509/31472 Fees: Free download Metadata_Reference_Information: Metadata_Date: 20250224 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