LA-ICP-MS uranium-lead zircon data from igneous rocks collected during the 2025 field season from the Steese-White Mountains and Chena project areas, Yukon-Tanana Upland, Alaska

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Frequently anticipated questions:


What does this data set describe?

Title:
LA-ICP-MS uranium-lead zircon data from igneous rocks collected during the 2025 field season from the Steese-White Mountains and Chena project areas, Yukon-Tanana Upland, Alaska
Abstract:
LA-ICP-MS uranium-lead zircon data from igneous rocks collected during the 2025 field season from the Steese-White Mountains and Chena project areas, Yukon-Tanana Upland, Alaska, Raw Data File 2026-11, contains uranium-lead (U-Pb) geochronologic data and trace and rare-earth element (TREE) data from single zircon spots analyzed by laser-ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). U-Pb ages and TREE concentrations were acquired simultaneously from the same zircon volumes. Zircon data from 14 igneous and meta-igneous rock samples, primarily collected during the 2025 White Mountains field season, in support of the United States Geological Survey's Earth Mapping Resources Initiative (USGS Earth MRI) Steese and Chena geologic mapping projects. These Earth MRI projects are part of the effort to modernize geologic mapping of the nation's surface and subsurface with a focus on collecting data in areas of potential critical mineral resources. The USGS selected the Yukon-Tanana Upland as the most likely area for new potential mineral resources in Alaska and has been the focus area of the DGGS Mineral Resources Section since 2019. Geologic mapping of the approximately 24,000 km2 study area was accomplished through a combination of new helicopter- and vehicle-supported field investigations and the integration of existing DGGS, USGS, industry, and academic data. The goal of this geochronologic dataset is to delineate the timing of igneous activity to support geologic mapping, tectonic interpretation, and mineralization studies throughout east-central Alaska. These data are provided as a Raw Data File under an open end-user license and are available on the DGGS website: http://doi.org/10.14509/32064.
Supplemental_Information:
age_summary:    Interpreted crystallization ages, sample location information, and sample descriptions.	
zircon_grain_data:    Zircon grain data, which contains U-Pb isotopic ages and TREE data for each analyzed zircon spot.
  1. How might this data set be cited?
    Buchanan, J.W., Barrera, M.L., and Newberry, R.J., 2026, LA-ICP-MS uranium-lead zircon data from igneous rocks collected during the 2025 field season from the Steese-White Mountains and Chena project areas, Yukon-Tanana Upland, Alaska: Raw Data File RDF 2026-11, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 4 p.
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -147.375806
    East_Bounding_Coordinate: -143.960550
    North_Bounding_Coordinate: 65.592704
    South_Bounding_Coordinate: 64.788365
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 2025
    Currentness_Reference:
    ground condition
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: spreadsheet
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      This is a point data set.
    2. What coordinate system is used to represent geographic features?
      Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.0000001. Longitudes are given to the nearest 0.0000001. Latitude and longitude values are specified in decimal degrees. The horizontal datum used is WGS84.
      The ellipsoid used is WGS 84.
      The semi-major axis of the ellipsoid used is 6378137.
      The flattening of the ellipsoid used is 1/298.257223563.
  7. How does the data set describe geographic features?
    rdf2026-11_white_mts_cz_age_summary.csv, rdf2026-11_white_mts_cz_age_summary_data_dictionary.csv
    Interpreted crystallization ages, sample location information, and sample descriptions. (Source: DGGS)
    rdf2026-11_white_mts_cz_zircon_grain_data.csv, rdf2026-11_white_mts_cz_zircon_grain_data_dictionary.csv
    Zircon grain data, which contains U-Pb isotopic ages and TREE data for each analyzed zircon spot. (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?
    The authors thank the University of Arizona LaserChron Center staff for their contributions to data collection, technical discussions, and other support. The analytical work was funded by the U.S. Geological Survey's Earth Mapping Resources Initiative (Earth MRI) under cooperative agreement G24AC00323 and by the State of Alaska. 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.
  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?

This dataset contains LA-ICP-MS U-Pb zircon ages and trace and rare-earth element data from 14 igneous and metaigneous samples collected for the USGS Earth MRI Steese and Chena mapping projects. These data support efforts to modernize geologic mapping in regions with critical mineral potential across the Yukon-Tanana Upland. The purpose of the dataset is to constrain the timing of igneous activity to inform geologic mapping, tectonic interpretations, and mineralization studies in east-central Alaska.

How was the data set created?

  1. From what previous works were the data drawn?
  2. How were the data generated, processed, and modified?
    Date: 2024 (process 1 of 3)
    Field data collection - DGGS geologists collected 2-5 kg of whole-rock samples from selected stations with minimal alteration and weathering. Sample station coordinates were recorded using GPS-enabled tablets running ESRI Field Maps, with approximately 10 m positional accuracy. Location coordinates for sample 76AWr287 were digitized from archival USGS materials. All location data are reported in latitude and longitude using the WGS84 datum.
    Date: 2025 (process 2 of 3)
    Sample analysis - DGGS and laboratory staff prepared zircon separates at the Arizona LaserChron Center (ALC), where whole-rock samples were crushed, milled, and processed by magnetic and density separation before removing soft minerals and accessory phases as needed. Approximately 60 zircon grains per sample were hand-picked, mounted in epoxy, and imaged using BSE, CL, and transmitted light to guide spot selection, with complex grains receiving multiple analyses. LA-ICP-MS analyses were performed using a Teledyne/Photon Machines Analyte G2 laser coupled to an Element2 HR mass spectrometer, with ~30-µm spots cleaned by pre-ablation and measured for U-Th-Pb isotopes and TREE elements. Standards FC-1, SL-2, and R33 were run between unknowns for drift monitoring. Data reduction followed established ALC protocols, including background subtraction, common-Pb correction, interference removal, fractionation calibration against reference materials, and uncertainty propagation using published methods. Additional details on laboratory methods and data reduction are provided in the accompanying report.
    Date: 2025 (process 3 of 3)
    Crystallization age calculation - The authors generated the crystallization age summary table by calculating weighted mean 206Pb/238U ages for 12 samples in IsoplotR v6.5 following Vermeesch (2018), reporting results with 2 sigma uncertainties. They compiled isotopic ratios, calculated ages, and elemental data for all zircon spot analyses in the zircon grain data table, while the laboratory rejected analyses with poor signal quality, high common Pb, discordance, or isotopic offsets; the analysis_error field documents each rejection, and N_total reflects the analyses that passed quality control. Weighted mean calculations incorporated only non-inherited zircon ages, and the table identifies which spot ages contributed to each mean. Two samples lacked interpretable crystallization ages: sample 25MLB215 produced no zircon, and sample 25MLB058 yielded few, very small grains dominated by inherited Proterozoic, Jurassic, Cretaceous, and Paleocene ages that were too scattered to define a reliable crystallization age.
  3. What similar or related data should the user be aware of?
    Buchanan, J.W., Barrera, M.L., Moshrefzadeh, J.A., Truskowski, C.M., and Newberry, R.J., 2025, LA-ICP-MS uranium-lead zircon data from samples in the Chena and Steese project areas: Raw Data File RDF 2025-25, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 4 p
    Moshrefzadeh, J.A., and Newberry, R.J., 2025, Electron probe microanalyzer data collected on samples from the Chena and Steese projects, Yukon-Tanana Uplands, Alaska: Raw Data File RDF 2025-13, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 6 p
    Moshrefzadeh, J.A., Barrera, M.L., Buchanan, J.W., Naibert, T.J., Newberry, R.J., Norwood, L.P., Regan, S.P., Szumigala, D.J., Twelker, Evan, Walser, S.L., and Wilson, K.R., 2025, Field station locations and magnetic susceptibility data collected in 2025 for the Steese project, Yukon-Tanana Uplands, Alaska: Raw Data File RDF 2025-28 v. 2, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 3 p
    Moshrefzadeh, J.A., Buchanan, J.W., Naibert, T.J., Twelker, Evan, Newberry, R.J., Szumigala, D.J., Barrera, M.L., Norwood, L.P., Acosta, M.D., and Regan, S.P., 2025, Field station locations and magnetic susceptibility data collected in 2024 for the Chena and Steese projects, Yukon-Tanana Uplands, Alaska: Raw Data File RDF 2025-5, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 5 p
    Moshrefzadeh, Jamshid, Acosta, M.D., Barrera, M.L., Buchanan, J.W., Naibert, T.J., Newberry, R.J., Norwood, L.P., Regan, S.P., Szumigala, D.J., and Twelker, Evan, 2025, Geochemical data from samples collected in 2024 for the Chena and Steese projects, Big Delta, Circle, Fairbanks, and Livengood quadrangles, Alaska: Raw Data File RDF 2025-17, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 3 p

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

  1. How well have the observations been checked?
    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.
  2. How accurate are the geographic locations?
    Staff recorded geographic coordinates for sample stations using GPS-enabled tablets and smartphones running the ESRI Field Maps application, which typically provides positional accuracy within approximately 10 meters. All location data are reported in latitude and longitude using the WGS84 datum.
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
    This data release is complete.
  5. How consistent are the relationships among the observations, including topology?
    Not applicable

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? RDF 2026-11
  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: 11-Mar-2026
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 Wed Mar 11 15:53:26 2026