Identification_Information: Citation: Citation_Information: Originator: Naibert, T.J. Originator: Heizler, M.T. Originator: Twelker, Evan Originator: Newberry, R.J. Originator: Wypych, Alicja Publication_Date: 2024 Title: 40Ar/39Ar geochronology data from the Ladue River-Mount Fairbanks area, eastern Alaska Geospatial_Data_Presentation_Form: csv Series_Information: Series_Name: Raw Data File Issue_Identification: RDF 2024-32 Publication_Information: Publication_Place: Fairbanks, Alaska, United States Publisher: Alaska Division of Geological & Geophysical Surveys Other_Citation_Details: 16 p. Online_Linkage: https://doi.org/10.14509/31454 Description: Abstract: 40Ar/39Ar geochronology data from the Ladue River-Mount Fairbanks area, eastern Alaska, Raw Data File 2024-32, provides 40Ar/39Ar geochronology results from rock samples collected in the Tanacross Quadrangle of eastern Alaska within the Ladue River drainage and the upper Dennison Fork of the Fortymile River drainage around Mount Fairplay. During the 2019 field season, geologists from the Alaska Division of Geological & Geophysical Surveys (DGGS) conducted geologic mapping and sampling in the Tanacross Quadrangle of eastern Alaska within the Ladue River drainage and the upper Dennison Fork of the Fortymile River drainage around Mount Fairplay. The area lies northeast of the Alaska Highway between Tok, Alaska, and the Canadian border. A recent geologic map of the area lies within the Yukon-Tanana Uplands, which DGGS and U.S. Geological Survey (USGS) identified as having the potential to host deposits of multiple critical minerals, as well as gold, copper, molybdenum, lead, zinc, and silver. Most known mineralization in the region is related to Cretaceous-Paleogene magmatism. These igneous rocks intrude metamorphic rocks of the North American continental margin and the structurally overlying allochthonous Yukon-Tanana Terrane, both of which are multiply deformed and juxtaposed along low-angle faults. Samples were collected for 40Ar/39Ar geochronology to further understand the crystallization ages of igneous rocks and the exhumation history of metamorphic rocks. This report's 18 40Ar/39Ar samples include one volcanic crystallization age, two pluton-alteration ages, and 15 metamorphic cooling ages. Differences in metamorphic cooling ages have been used to distinguish the allochthonous Yukon-Tanana Terrane from parautochthonous North America. The 15 metamorphic samples with cooling ages reported here were collected to aid in DGGS field mapping near this major terrane boundary. Allochthonous samples include eight samples from the Ladue River assemblage with muscovite cooling ages between ca. 105 and 235 Ma; a sample from the Klondike assemblage with a muscovite cooling age of ca. 147 Ma; a sample from the Fortymile River assemblage with a muscovite cooling age of ca. 186 Ma. Parautochthonous North America samples include a sample from the Jarvis assemblage with a muscovite cooling age of ca. 149 Ma and four samples from the Lake George assemblage with muscovite cooling ages of ca. 100 and 105 Ma and hornblende cooling ages of ca. 127 and 255 Ma. These data and report are available from the DGGS website: http://doi.org/10.14509/31454. Purpose: The Eastern Tanacross project aimed to complete a 1:100,000 scale bedrock geologic map of a 1900 square mile area of the eastern Tanacross Quadrangle and part of the Nabsena Quadrangle. It is funded through the USGS Earth MRI program and targets an area of Alaska prospective for rare earth elements, other critical minerals, and conventional minerals including gold, copper, molybdenum, and silver. 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: 2019 Ending_Date: 2024 Currentness_Reference: ground condition Status: Progress: Complete Maintenance_and_Update_Frequency: None planned Spatial_Domain: Bounding_Coordinates: West_Bounding_Coordinate: -142.489000 East_Bounding_Coordinate: -141.006900 North_Bounding_Coordinate: 63.687100 South_Bounding_Coordinate: 62.805900 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: Alteration Products 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: Bedrock Theme_Keyword: Bedrock Geology Theme_Keyword: DGGS Theme_Keyword: Exploration Theme_Keyword: Geochronology Theme_Keyword: Geologic Theme_Keyword: Geology Theme_Keyword: Granite Theme_Keyword: Granodiorite Theme_Keyword: Greenschist Theme_Keyword: Hornblende Theme_Keyword: Igneous Theme_Keyword: Igneous Rocks Theme_Keyword: Isotopes Theme_Keyword: Lab Methods Theme_Keyword: Metamorphic Theme_Keyword: Metamorphic Rocks Theme_Keyword: Metamorphism Theme_Keyword: Methods Theme_Keyword: Mineral Resources Theme_Keyword: Mineralogy Theme_Keyword: Minerals Theme_Keyword: Muscovite Theme_Keyword: Orthogneiss Theme_Keyword: Plagioclase Theme_Keyword: Resources Theme_Keyword: Rocks Theme_Keyword: Sample Location Theme_Keyword: Schist Theme_Keyword: Separation Theme_Keyword: Sericite Theme_Keyword: Trachyandesite Place: Place_Keyword_Thesaurus: Alaska Division of Geological & Geophysical Surveys Place_Keyword: Big Creek Place_Keyword: Gardiner Creek Place_Keyword: Ladue River Place_Keyword: McArthur Creek Stratum: Stratum_Keyword_Thesaurus: Alaska Division of Geological & Geophysical Surveys Stratum_Keyword: Fortymile River Assemblage Stratum_Keyword: Jarvis Belt Stratum_Keyword: Klondike Assemblage Stratum_Keyword: Ladue River Assemblage Stratum_Keyword: Lake George Assemblage 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 Eastern Tanacross project was jointly funded by the State of Alaska and the U.S. Geological Survey's Earth Mapping Resources Initiative (EarthMRI) through cooperative agreement G19AC00262. We are grateful to have had access to Doyon Limited lands within the study area. 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: Naibert, T.J. Originator: Twelker, Evan Originator: Wypych, Alicja Originator: Athey, J.E. Originator: Newberry, R.J. Originator: Lopez, J.A. Originator: Regan, S.P. Originator: Sicard, K.R. Originator: Wildland, A.D. Originator: Wyatt, W.C. Publication_Date: 2020 Title: Field station locations and magnetic susceptibility data collected in 2019 for the Eastern Tanacross Project, Tanacross and Nabesna quadrangles, Alaska Series_Information: Series_Name: Raw Data File Issue_Identification: RDF 2019-9 Publication_Information: Publication_Place: Fairbanks, Alaska, United States Publisher: Alaska Division of Geological & Geophysical Surveys Other_Citation_Details: 2 p Online_Linkage: https://doi.org/10.14509/30268 Cross_Reference: Citation_Information: Originator: Newberry, R.J. Publication_Date: 2020 Title: The Mount Fairplay igneous complex Series_Information: Series_Name: Preliminary Interpretive Report Issue_Identification: PIR 2020-1 Publication_Information: Publication_Place: Fairbanks, Alaska, United States Publisher: Alaska Division of Geological & Geophysical Surveys Other_Citation_Details: 32 p Online_Linkage: https://doi.org/10.14509/30463 Cross_Reference: Citation_Information: Originator: Twelker, Evan Originator: O'Sullivan, P.B. Publication_Date: 2021 Title: U-Pb detrital zircon geochronology of Cretaceous-Cenozoic sedimentary rocks in the Ladue River-Mount Fairplay area, Alaska Series_Information: Series_Name: Preliminary Interpretive Report Issue_Identification: PIR 2021-2 Publication_Information: Publication_Place: Fairbanks, Alaska, United States Publisher: Alaska Division of Geological & Geophysical Surveys Other_Citation_Details: 16 p Online_Linkage: https://doi.org/10.14509/30683 Cross_Reference: Citation_Information: Originator: Twelker, Evan Publication_Date: 2021 Title: Geologic investigation of the Ladue River-Mount Fairplay area, eastern Alaska Series_Information: Series_Name: Report of Investigation Issue_Identification: RI 2021-5 Publication_Information: Publication_Place: Fairbanks, Alaska, United States Publisher: Alaska Division of Geological & Geophysical Surveys Other_Citation_Details: 86 p Online_Linkage: https://doi.org/10.14509/30734 Cross_Reference: Citation_Information: Originator: Wildland, A.D. Originator: Wypych, Alicja Originator: Regan, S.P. Originator: Holland, Mark Publication_Date: 2021 Title: U-Pb zircon ages from bedrock samples collected in the Tanacross and Nabesna quadrangles, eastern Alaska Series_Information: Series_Name: Preliminary Interpretive Report Issue_Identification: PIR 2021-4 Publication_Information: Publication_Place: Fairbanks, Alaska, United States Publisher: Alaska Division of Geological & Geophysical Surveys Other_Citation_Details: 47 p Online_Linkage: https://doi.org/10.14509/30732 Cross_Reference: Citation_Information: Originator: Wypych, Alicja Originator: Twelker, Evan Originator: Naibert, T.J. Originator: Athey, J.E. Originator: Newberry, R.J. Originator: Lopez, J.A. Originator: Regan, S.P. Originator: Sicard, K.R. Originator: Wildland, A.D. Originator: Wyatt, W.C. Publication_Date: 2019 Title: Major-oxide and trace-element geochemical data from rocks collected in 2019 for the Eastern Tanacross project, Tanacross and part of Nabesna quadrangles, Alaska Series_Information: Series_Name: Raw Data File Issue_Identification: RDF 2019-8 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/10.14509/30267 Data_Quality_Information: Attribute_Accuracy: Attribute_Accuracy_Report: The accompanying report provides a comprehensive discussion of processing methods. When applicable, errors are reported in the data tables. These data are being released in the DGGS Raw Data File series. Reports in this series present field data and analytical results with limited or no interpretation by DGGS staff or project collaborators. Analytical results may include interpretations by laboratories when an interpretive review of the analytical findings is necessary to develop usable output. The reports and accompanying data have been evaluated by project staff for general readability and logical consistency but have not 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: We recorded location information using GPS-enabled tablets running Esri ArcGIS Field Maps app, with a reported horizontal error of approximately 5 to 10 meters. Latitude and longitude are reported in the WGS84 coordinate system. Lineage: Process_Step: Process_Description: Sample collection and analysis - Fresh, unweathered samples from surface outcrops were collected by DGGS field geologists for dating. Sample location coordinates (in WGS84 datum) were obtained using GPS-enabled field tablets with a typical reported accuracy of +/- 10 meters. Samples were examined under a binocular microscope and/or in thin section to select unaltered mineral phases before sample preparation. Process_Date: 2019 Process_Step: Process_Description: Sample preparation - Twenty-four samples were submitted to the New Mexico Geochronological Research Laboratory (NMGRL) in Socorro, New Mexico. Nineteen samples yielded acceptable mineral separates for 40Ar/39Ar geochronology. Muscovite and/or hornblende were separated from rock samples using standard magnetic, heavy liquid, and hand-picking procedures. The samples were loaded into machined aluminum discs and irradiated for 16 hours at the USGS reactor in Denver, Colorado (NM-316), or for 14 hours at the Oregon State University reactor in Corvallis, Oregon (NM-312), 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: 2019 Process_Step: Process_Description: Analytical methods - After irradiation, the samples and monitors were analyzed by step-heating with a 75W 810 nm diode laser. The samples were step-heated using between 12 and 16 increments. Reactive gases were removed by a 60-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: 2020 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: rdf2024_032-summary_data.csv, rdf2024_032-summary_data_dictionary.csv, rdf2024_032-step_heating_data.csv, rdf2024_032-step_heating_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 2024-32 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: 20241211 Format_Information_Content: table Digital_Transfer_Option: Online_Option: Computer_Contact_Information: Network_Address: Network_Resource_Name: https://doi.org/10.14509/31454 Fees: Free download Metadata_Reference_Information: Metadata_Date: 20241211 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