Major-oxide and trace-element analyses of rock samples from the West Susitna area STATEMAP project, southcentral, Alaska

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Frequently anticipated questions:

What does this data set describe?

Title:
Major-oxide and trace-element analyses of rock samples from the West Susitna area STATEMAP project, southcentral, Alaska
Abstract:
Major-oxide and trace-element analyses of rock samples from the West Susitna area STATEMAP project, southcentral, Alaska, Raw Data File 2025-21, provides whole-rock geochemical analyses, including major-oxide and trace-element concentrations, from bedrock samples that DGGS staff collected during the 2024 field season as part of the Alaska Division of Geological & Geophysical Surveys' (DGGS) West Susitna STATEMAP project. The project is a 1:50,000-scale geologic mapping initiative to characterize geology, assess geologic hazards, and investigate tectonic features within a region of increasing interest for resource development, alternative energy, and recreation. The study area lies in the West Susitna region of southcentral Alaska. It spans approximately 500 mi2 across the Tyonek C-3, C-4, D-4, and D-5 quadrangles, including ~50 miles of the proposed West Susitna Access Corridor that connects Anchorage to the Happy River Valley on the western margin of the Susitna Basin. Major- and trace-element geochemical analyses were obtained for plutonic and volcanic rocks to define map units and determine the magmatic history of the area. 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/10.14509/31725.
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?
    Walser, S.L., Gillis, R.J., Bernt, J.D., and Montayne, Simone, 2025, Major-oxide and trace-element analyses of rock samples from the West Susitna area STATEMAP project, southcentral, Alaska: Raw Data File RDF 2025-21, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 2 p
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -151.871951
    East_Bounding_Coordinate: -151.150545
    North_Bounding_Coordinate: 61.904571
    South_Bounding_Coordinate: 61.657942
  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: 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?
    This work was funded by the U.S. Geological Survey National Cooperative Geologic Mapping Program under STATEMAP award number GS23AS00050, 2023, and 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 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 or by any branch or employee of the State of Alaska.
  3. To whom should users address questions about the data?
    Alaska Division of Geological & Geophysical Surveys
    GIS Manager
    3354 College Rd
    Fairbanks, AK
    USA

    907-451-5020 (voice)
    dggsgis@alaska.gov
    Hours_of_Service: 8 am to 4:30 pm, Monday through Friday, except State holidays

Why was the data set created?

This geochemical data release provides whole-rock geochemical analyses from bedrock samples collected during DGGS's 2024 West Susitna STATEMAP project. The data support 1:50,000-scale geologic mapping and help characterize magmatic history, geology, and resource potential in a region of growing interest for mineral development, infrastructure expansion, and recreation.

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)
    Sample selection - DGGS staff collected fist-sized rock specimens for whole-rock major-oxide and trace-element geochemical analysis to support lithologic classification, unit correlation, and interpretation of the regional tectonic framework. They selected the least altered exposures at each site to ensure representative geochemical signatures. 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.
    Date: 2025 (process 2 of 3)
    Sample preparation - DGGS staff trimmed samples using a rock saw to remove weathering rinds and altered areas. ALS Geochemistry then processed the samples using their PREP-31 package. The samples were crushed to greater than 70 percent passing 2 mm, and a 250 g split was pulverized to greater than 85 percent passing 75 microns. The pulverizers were cleaned with “barren” material between sample processing.
    Date: 2025 (process 3 of 3)
    Geochemistry - ALS Geochemistry analyzed the samples for major and trace element suites using a range of techniques. Trace elements, including rare-earth elements, were determined using lithium metaborate fusion digestion followed by inductively coupled plasma mass spectrometry (ICP-MS), following method ME-MS81. Major and minor oxides were analyzed using lithium metaborate fusion digestion and inductively coupled plasma atomic emission spectrometry (ICP-AES), according to method ME-ICP06. Elements such as Ag, Cd, Co, Cu, Li, Mo, Ni, Pb, Sc, and Zn were measured using four-acid digestion and ICP-AES (method ME-4ACD81), while As, Bi, Hg, In, Re, Sb, Se, Te, and Tl were determined by aqua regia digestion followed by ICP-MS (method ME-MS42). Total carbon and sulfur concentrations were measured using a Leco furnace, following methods C-IR07 and S-IR08, respectively. DGGS ensured analytical accuracy by including one standard reference material for every batch of 10 samples, alongside ALS Geochemistry’s ISO/IEC 17025:2005 accredited internal quality-control procedures.
  3. What similar or related data should the user be aware of?
    Gillis, R.J., 2015, Overview of 2014 energy-focused studies in Susitna basin, south-central Alaska, and preliminary results: Preliminary Interpretive Report PIR 2015-3, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 34 p
    Gillis, R.J., Stanley, R.G., LePain, D.L., Mauel, D.J., Herriott, T.M., Helmold, K.P., Peterson, C.S., Wartes, M.A., and Shellenbaum, D.P., 2013, Status of a reconnaissance field study of the Susitna basin, 2011: Preliminary Interpretive Report PIR 2013-4, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 8 p
    Zechmann, J.M., and Salisbury, J.B., 2025, Lidar-derived surface elevation data for Dickason Highlands, Southcentral Alaska, collected August 14, 2024: Raw Data File RDF 2025-12, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 10 p

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

  1. How well have the observations been checked?
    DGGS ensured analytical accuracy by including one standard reference material for every batch of 10 samples. ALS Geochemistry's internal quality-control procedures are accredited under ISO/IEC 17025:2005.
  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 NAD83 datum.
  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)
    State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys
    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 (http://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 2025-21
  3. What legal disclaimers am I supposed to read?
    The State of Alaska makes no express or implied warranties (including warranties of merchantability and fitness) with respect to the character, function, or capabilities of the electronic services 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, any failure thereof, or otherwise, and 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: 23-Oct-2025
Metadata author:
Simone Montayne
3354 College Road
Fairbanks, AK
USA

907-451-5020 (voice)
Metadata standard:
FGDC Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
Metadata extensions used:
Generated by mp version 2.9.50 on Thu Oct 23 16:46:54 2025