Geochemical data from samples collected in 2023 for the Chena and Mount Harper projects, Big Delta, Circle, Fairbanks, and Eagle quadrangles, Alaska

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Frequently anticipated questions:

What does this data set describe?

Title:
Geochemical data from samples collected in 2023 for the Chena and Mount Harper projects, Big Delta, Circle, Fairbanks, and Eagle quadrangles, Alaska
Abstract:
Geochemical data from samples collected in 2023 for the Chena and Mount Harper projects, Big Delta, Circle, Fairbanks, and Eagle quadrangles, Alaska, Raw Data File 2024-2, presents whole-rock and major- and trace-element geochemistry of rock samples collected to support 1:100,000-scale bedrock geologic mapping of ~5,750 mi2 (~15,000 km2) in portions of the Big Delta and Circle quadrangles and parts of the Fairbanks and Eagle quadrangles, Alaska. These samples were collected to support the Chena and Mount Harper/Richardson mapping projects, both of which are integral parts of the U.S. Geological Survey's Earth Mapping Resource Initiative (USGS Earth MRI) program. The aim of Earth MRI is to update the nation's surface and subsurface mapping to improve the knowledge of the country's overall geologic framework, with a specific focus on identifying areas that may contain undiscovered critical mineral resources. This raw data file (RDF) includes major oxide and trace element geochemistry of metamorphic and igneous rocks and potentially mineralized rocks sampled from the Chena and Mount Harper/Richardson project areas. Station location and field rock descriptions for the samples can be found in Gavel and others (2023). These geochemical analyses will further our understanding of potential mineral resources in the area, help distinguish between igneous and sedimentary protoliths in metamorphic rocks, and be used to characterize the Mesozoic and Cenozoic magmatic events. The regional geology is composed of structurally bound assemblages of polydeformed Paleozoic metasedimentary and metaigneous rocks ranging from lower greenschist to upper amphibolite facies. These rocks are structurally overlain by allochthonous oceanic mafic and ultramafic rocks of the Seventymile terrane at Nail Ridge. The metamorphic sequences are intruded by Cretaceous to Paleocene plutons. The Chena and Mount Harper/Richardson projects surround areas of historical mining activity, current production, and future potential mineral resource development. Granitic plutons were emplaced during multiple magmatic pulses in the mid-Cretaceous, spanning 115-90 Ma. This period of magmatism and deformation is associated with gold (+/- tellurium, bismuth, antimony, and arsenic) mineralization at the Pogo Mine and nearby prospects along the Pogo trend, including West Pogo, East Pogo, and Tibbs. Some latest Cretaceous to early Paleogene magmatism is associated with tungsten mineralization (Big Windy and Furs W skarn prospects). Tin- and rare earth element (REE)-bearing granites and peralkaline intrusions exist within the field areas and in historical and modern placer gold mines. This data file is released as a Raw Data File with an open end-user license. The data are available from the DGGS website: http://doi.org/10.14509/31123.
Supplemental_Information: 
geochemistry-download:    Digital data available through the Alaska Geochemistry database online. Download files include data, analytical methods, and detection limits.
  1. How might this data set be cited?
    Buchanan, J.W., Wypych, Alicja, Barrera, M.L., Biegel, J.M., Gavel, M.M., Harvey, D.A., Ketcham, R.A., Muller, I.P., Naibert, T.J., Newberry, R.J., Regan, S.P., Szumigala, D.J., Twelker, Evan, and Wildland, A.D., 2025, Geochemical data from samples collected in 2023 for the Chena and Mount Harper projects, Big Delta, Circle, Fairbanks, and Eagle quadrangles, Alaska: Raw Data File RDF 2024-2, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 5 p.
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -147.224223
    East_Bounding_Coordinate: -143.920406
    North_Bounding_Coordinate: 65.186061
    South_Bounding_Coordinate: 64.182181
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 2023
    Currentness_Reference:
    ground condition
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: csv
  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 0.000001. Longitudes are given to the nearest 0.000001. Latitude and longitude values are specified in decimal degrees. The horizontal datum used is NAD83.
      The ellipsoid used is GRS 80.
      The semi-major axis of the ellipsoid used is 6378137.
      The flattening of the ellipsoid used is 1/298.257222101.
  7. How does the data set describe geographic features?
    geochemistry-download
    Digital data available through the Alaska Geochemistry database online. Download files include data, analytical methods, and detection limits. (Source: Alaska Division of Geological & Geophysical Surveys (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 geologic mapping portion of the 2023 field season was funded by the U.S. Geological Survey Earth Mapping Resources Initiative under Cooperative Agreement Number G23AC00372 and by State of Alaska Capital Improvement funds. The geochemical analyses reported herein were funded 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 USGS. Any mention of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the USGS or the DGGS.
  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?

These geochemical analyses further our understanding of potential mineral resources in the area, help distinguish between igneous and sedimentary protoliths in metamorphic rocks, and be used to characterize the Mesozoic and Cenozoic magmatic events.

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: 2023 (process 1 of 4)
    Field data collection - During the 2023 summer field season, geologists from DGGS conducted 1:100,000-scale bedrock geologic mapping of ~5,750 mi2 (~15,000 km2) within the Big Delta and Circle quadrangles and parts of the Fairbanks and Eagle quadrangles, Alaska. Geologists collected representative rock samples for whole-rock major-oxide and trace-element geochemistry to aid in the classification of rock units, correlation of units over the map area, and understanding of the tectonic setting. They obtained sample locations using GPS-enabled tablets and smartphones running the Esri Field Maps App, which has a reported error of approximately 10 m.
    Date: 2023 (process 2 of 4)
    Sample selection - Rock samples collected for geochemical analyses fall into two categories with different purposes. Igneous, metaigneous, and metasedimentary rocks showing little alteration or weathering were collected for whole-rock major-oxide, minor-oxide, and trace-element analyses (MOX). These MOX samples are geographically dispersed and aid in rock classification, protolith identification, petrogenesis, and discrimination of tectonic setting. Additionally, any rock types with visible mineralization or alteration were preferentially collected and analyzed for trace-element geochemistry (GX).
    Date: 2023 (process 3 of 4)
    Sample preparation - DGGS staff trimmed MOX samples to remove weathering, small alteration zones, or any other heterogeneities before they were sent for analysis. GX samples were left as collected in the field. All samples were processed and analyzed by Bureau Veritas Commodities Canada Ltd. Mineral Laboratories (BV). All samples were crushed to greater than 70 percent passing through a 2-mm screen, and a 250-g split was pulverized to greater than 85 percent passing through a 75-micron screen (BV package PRP70-250).
    Date: 2023 (process 4 of 4)
    Geochemistry - All whole-rock major-oxide, minor-oxide, and trace-element analyses samples (MOX) were analyzed with BV package LF202, which includes the following analytes and methods: LF300, GRAV, LF100, TC000, and AQ200. All MOX samples were analyzed with BV packages for either Au or Au, Pt, and Pd, depending on the possibility of the rock sample including Platinum Group Elements (PGEs). Six MOX samples were analyzed with additional packages to provide elemental information not covered in other analytical packages. All mineralized (GX) samples were analyzed with BV package MA250 for major- and trace-element values. GX samples were also analyzed with BV packages for either Au (FA330) or Au, Pt, and Pd (FA130) with the same methods described above. Eighteen GX samples were analyzed with AQ251 for additional elements with the same methods described above. Nine GX samples had individual elemental analyses over the upper detection limit of the methods described above and were reanalyzed with methods more suited for higher concentrations.
  3. What similar or related data should the user be aware of?
    Gavel, M.M., Twelker, Evan, Wypych, Alicja, Naibert, T.J., Newberry, R.J., Szumigala, D.J., Wildland, A.D., Barrera, M.L., Biegel, J.N., Harvey, D.A., Ketcham, R.A., Muller, I.P., and Regan, S.P., 2023, 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: Raw Data File RDF 2023-27, 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?
    In addition to BV Mineral Laboratories' accredited (ISO/IEC 17025) internal quality-control program, DGGS monitored analysis quality with one reference-material standard per batch of 20 analyses.
  2. How accurate are the geographic locations?
    Location data were collected using GPS-enabled tablets and smartphones running the ESRI Field Maps App. Data were merged into an ArcGIS geodatabase. The devices have a reported error of about 10 m.
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
    This data releaase 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 2024-2
  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: 28-Jan-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 Tue Jan 28 20:02:56 2025