Magmatic and structural framework of PGE and other mineralization in northwestern Wrangellia, central Alaska

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Frequently anticipated questions:

What does this data set describe?

Title:
Magmatic and structural framework of PGE and other mineralization in northwestern Wrangellia, central Alaska
Abstract:
A thick and regionally extensive sequence of low-grade-metamorphosed Late Triassic basaltic rocks, the Nikolai Greenstone, is a characteristic component of the stratigraphy of the Wrangellia terrane in central and southeastern Alaska, Yukon, and British Columbia. Mafic to ultramafic intrusions feeding this extensive volcanic province hold high geologic potential for discovery of economically signifigant magmatic sulfide deposits. This digital data file provides microprobe compositions of olivine and pyroxine from ultramafic samples across the study area. Mineral compositions and the ratio of molar MgO per(MgO+FeO) interpret magma evolution and provide insight into the magmatic-geochemical framework of Ni-Cu-Co-PGE mineralization related to the Butte, Rainy, Eureka, Canwell, and Talkeetna Mountains intrusions. These data accompany a summary report of findings from a multiyear Alaska Division of Geological & Geophysical Surveys (DGGS) project to better understand the geologic context of mineralization hosted by the Wrangellia terrane in the eastern Alaska Range and Talkeetna Mountains, with particular emphasis on evaluating the area's potential for hosting the strategic and critical platinum-group elements (PGEs) and cobalt (Co). Users can access the complete report and digital data from the DGGS website: http://doi.org/10.14509/30468.
Supplemental_Information: 
microprobe-data: Sample locations, measured mineral compositions, and calculated ratios of molar MgO per(MgO+FeO).
  1. How might this data set be cited?
    Twelker, Evan, Lande, L.L., Newberry, R.J., Wypych, Alicja, Sicard, K.R., and Freeman, L.K., 2020, Magmatic and structural framework of PGE and other mineralization in northwestern Wrangellia, central Alaska: Report of Investigation RI 2020-6, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 72 p.
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -148.635600
    East_Bounding_Coordinate: -145.701100
    North_Bounding_Coordinate: 63.355800
    South_Bounding_Coordinate: 62.583800
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 2013
    Ending_Date: 2020
    Currentness_Reference:
    ground condition
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: report and digital data
  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 0.00001. Longitudes are given to the nearest 0.00001. Latitude and longitude values are specified in decimal degrees. The horizontal datum used is World Geodetic System of 1984.
      The ellipsoid used is WGS 84.
      The semi-major axis of the ellipsoid used is 6378137.
      The flattening of the ellipsoid used is 1/298.257223563000025.
  7. How does the data set describe geographic features?
    ri2020-006-microprobe-data.csv, ri2020-006-microprobe-data-dictionary.csv
    Sample locations, measured mineral compositions, and calculated ratios of molar MgO per(MgO+FeO). (Source: Alaska Division of Geological & Geophysical Surveys)
    sample
    A generic example of a sample identifier: YYAAA9999X: YY=last two digits of year, AAA=initials (one to three characters), 9999=unique station number, X= optional alpha character, which indicates that multiple samples were collected at a given location or that multiple observations were recorded in the project database. (Source: this report) string
    mineral_analyzed
    The mineral analyzed by electron probe micro-analysis (Source: this report) string
    latitude_wgs84
    latitude, WGS84 (Source: this report) number
    longitude_wgs84
    longitude, WGS84 (Source: this report) number
    intrusion
    Mafic-ultramafic intrusive complex name referenced in the report (Source: this report) string
    points_averaged
    The number of individual microprobe spot analyses averaged (Source: this report) number
    SiO2_pct
    The un-normalized concentration of SiO2, measured in percent, by electron probe micro-analysis wavelength dispersive X-ray spectroscopy (Source: this report) number
    TiO2_pct
    The un-normalized concentration of TiO2, measured in percent, by electron probe micro-analysis wavelength dispersive X-ray spectroscopy (Source: this report) number
    Al2O3_pct
    The un-normalized concentration of Al2O3, measured in percent, by electron probe micro-analysis wavelength dispersive X-ray spectroscopy (Source: this report) number
    FeO_pct
    The un-normalized concentration of total Fe as FeO, measured in percent, by electron probe micro-analysis wavelength dispersive X-ray spectroscopy (Source: this report) number
    MnO_pct
    The un-normalized concentration of MnO, measured in percent, by electron probe micro-analysis wavelength dispersive X-ray spectroscopy (Source: this report) number
    MgO_pct
    The un-normalized concentration of MgO, measured in percent, by electron probe micro-analysis wavelength dispersive X-ray spectroscopy (Source: this report) number
    Na2O
    The un-normalized concentration of Na2O, measured in percent, by electron probe micro-analysis wavelength dispersive X-ray spectroscopy (Source: this report) number
    CaO_pct
    The un-normalized concentration of CaO, measured in percent, by electron probe micro-analysis wavelength dispersive X-ray spectroscopy (Source: this report) number
    Cr2O3
    The un-normalized concentration of Cr2O3, measured in percent, by electron probe micro-analysis wavelength dispersive X-ray spectroscopy (Source: this report) number
    Ni_ppm
    The un-normalized concentration of Ni, measured in ppm, by electron probe micro-analysis wavelength dispersive X-ray spectroscopy (Source: this report) number
    total
    The total of all analyzed elements (Source: this report) number
    Mg_number
    Molar MgO / (MgO+FeO) (Source: this report) number
    calculated_melt_Mg_number
    The calculated melt Mg number (Mg #) based on a mineral-melt partition coefficient, Kd (Fe/ Mg), of 0.32 for olivine and 0.20 for clinopyroxene (Source: this report) number
    calculated_melt_TiO2
    Calculated melt TiO2 based on a mineral-melt partition coefficient, Kd (TiO2), of 0.007 for olivine and 0.45 for clinopyroxene (Source: this report) number

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 Alaska Legislature funded this project as part of the State's Strategic and Critical Minerals Assessment project (part of the DGGS Airborne Geophysical/Geological Mineral Inventory [AGGMI] program). Fieldwork in summer 2014 in the Talkeetna Mountains was also partially funded by the USGS National Cooperative Geologic Mapping Program, STATEMAP component, under award number G14AC00167 for 2014. The views and conclusions in this document are those of the authors. They should not be interpreted as necessarily representing the official policies, either expressed or implied, of the U.S. Government.
  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

Why was the data set created?

These data accompany a summary report of findings from a multiyear Alaska Division of Geological & Geophysical Surveys (DGGS) project to better understand the geologic context of mineralization hosted by the Wrangellia terrane in the eastern Alaska Range and Talkeetna Mountains, with particular emphasis on evaluating the area's potential for hosting the strategic and critical platinum-group elements (PGEs) and cobalt (Co).

How was the data set created?

  1. From what previous works were the data drawn?
    Lande, L.L., 2016 (source 1 of 1)
    Lande, L.L., 2016, A petrological model for emplacement of the ultramafic Ni-Cu-PGE alpha complex, eastern Alaska Range: University of Alaska Fairbanks, Fairbanks, Alaska.

    Online Links:

    Type_of_Source_Media: paper
    Source_Contribution: microprobe analysis
  2. How were the data generated, processed, and modified?
    Date: 2015 (process 1 of 2)
    Sample collection - During the 2013, 2014, 2015 field seasons, geologists from the Alaska Division of Geological & Geophysical Surveys (DGGS) conducted geologic mapping and sampling throughout the Wrangellia geologic belt. Igneous and metaigneous rocks showing little alteration or weathering were collected for whole-rock major-oxide, minor-oxide, and trace-element analyses to aid in classification and study of petrogenesis and tectonic setting. Most samples are grab samples, which were collected for their overall representation of the outcrop.
    Date: 2016 (process 2 of 2)
    Microprobe analysis - Mineral compositions of olivine and clinopyroxene grains were anayzed using the University of Alaska Fairbanks JEOL JXA-8530F Electron Microprobe, with a beam current of 25 nA at 20 KeV and a beam diameter of 10 microns. Ca was measured using the PETL crystal, Fe and Ni were measured using LiFL crystals, and Mg and Si were measured using TAPL crystals. Count times were 2 minutes on peak and 2 minutes on background. As noted in tables 1 and 2 of the accompanying report, some of the analyses used routines similar to those documented in Lande (2016). Data sources used in this process:
    • Lande, L.L., 2016
  3. What similar or related data should the user be aware of?
    Benowitz, J.A., Layer, P.W., Wypych, Alicja, and Twelker, Evan, 2015, 40Ar/39Ar data from the Talkeetna Mountains C-4 Quadrangle and adjoining areas, central Alaska: Raw Data File RDF 2015-10, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 19 p
    Benowitz, J.A., Layer, P.W., Wypych, Alicja, and Twelker, Evan, 2017, 40Ar/39Ar data from rocks collected in the 2015 Wrangellia mineral assessment project area, Mount Hayes A-5, Mount Hayes B-6, and Talkeetna Mountains D-2 quadrangles, Alaska: Raw Data File RDF 2017-1, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 9 p
    Benowitz, J.A., Layer, P.W., and Twelker, Evan, 2014, 40Ar/39Ar data from rocks collected in 2013 in the Wrangellia mineral assessment area, Gulkana, Healy, Mount Hayes, and Talkeetna Mountains quadrangles, Alaska: Raw Data File RDF 2014-18, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 10 p
    Holm-Denoma, C.S., Sicard, K.R., and Twelker, Evan, 2020, U-Pb geochronology of igneous and detrital zircon samples from the Tok River area, eastern Alaska Range, and Talkeetna Mountains, Alaska: Raw Data File RDF 2020-3, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 20 p
    Lande, Lauren, Newberry, R.J., and Twelker, Evan, 2015, A petrological model for emplacement of the ultramafic Ni-Cu-PGE Alpha complex, eastern interior Alaska (poster): Geological Society of America Cordilleran Section - 111th Annual Meeting, Anchorage, Alaska, May 11-13, 2015: Poster and Presentation Lande, Lauren and others, 2015, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 1 sheet
    Naibert, T.J., Benowitz, J.A., Wypych, Alicja, Sicard, K.R., and Twelker, Evan, 2018, 40Ar/39Ar data from the Tanacross D-1 and D-2, Big Delta B-4 and B-5, and Mount Hayes A-6 quadrangles, Alaska: Raw Data File RDF 2018-3, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 15 p
    Todd, Erin, Kylander-Clark, Andrew, Wypych, Alicja, Twelker, Evan, and Sicard, K.R., 2017, U-Pb and Lu-Hf isotope, age, and trace-element data from zircons at four sites in the western Alaska Range and Talkeetna Mountains, Alaska: Raw Data File RDF 2017-2, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 7 p
    Twelker, Evan, 2017, Geologic mapping in the Talkeetna Mountains and eastern Alaska Range: A story of mineralization and deformation (presentation): Alaska Geological Society Luncheon, February 21, 2017: Poster and Presentation Twelker, Evan, 2017, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 49 p
    Twelker, Evan, Bachmann, E.N., Freeman, L.K., Newberry, R.J., Reioux, D.A., Sicard, K.R., Tuzzolino, A.L., Wright, T.C., and Wypych, Alicja, 2014, Major-oxide, minor-oxide, and trace-element geochemical data from rocks and stream sediments in the Wrangellia mineral assessment area, Gulkana, Healy, Mount Hayes, and Talkeetna Mountains quadrangles, Alaska: Raw Data File RDF 2014-3, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 6 p
    Twelker, Evan, Hubbard, T.D., Wypych, Alicja, Sicard, K.R., Newberry, R.J., Reioux, D.A., Freeman, L.K., and Lande, L.L., 2015, Geologic map of the Talkeetna Mountains C-4 Quadrangle and adjoining areas, central Alaska: Preliminary Interpretive Report PIR 2015-6, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 16 p., 1 sheet, scale 1:50,000
    Twelker, Evan, Newberry, R.J., Freeman, L.K., Sicard, K.R., Reioux, D.A., and Bachmann, E.N., 2013, DGGS geologic and mineral-resource assessment of the western Wrangellia terrane, central Alaska: Initial progress report (presentation): Alaska Miners Association Annual Convention, Anchorage, Alaska, November 4-10, 2013: Poster and Presentation Twelker, Evan and others, 2013, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 25 p
    Twelker, Evan, Waldien, T.S., Newberry, R.J., Freeman, L.K., Sicard, K.R., Lande, L.L., Wypych, Alicja, Reioux, D.A., and Bachmann, E.N., 2020, Bedrock geologic map of the eastern Denali Highway area, Mount Hayes, Healy, and Talkeetna Mountains quadrangles, Alaska: Report of Investigation RI 2020-7, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Twelker, Evan, Wypych, Alicja, Sicard, K.R., Newberry, R.J., Freeman, L.K., Reioux, D.A., and Lande, Lauren, 2014, Preliminary results from 2014 geologic mapping in the Talkeetna Mountains, Alaska (presentation): Alaska Miners Association Annual Convention, Anchorage, Alaska, November 3-9, 2014: Poster and Presentation Twelker, Evan and others, 2014, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 28 p
    Twelker, Evan, Wypych, Alicja, and Newberry, R.J., 2014, New data and insight on the Late Triassic Wrangellia magmatic Ni-Cu-Co-PGE system in the Talkeetna Mountains, central Alaska (poster): Society of Economic Geologists 2014 Conference, September 27-30, 2014: Poster and Presentation Twelker, Evan and others, 2014, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 1 sheet
    Twelker, Evan, and Burns, L.E., 2014, New geochemical and geophysical data from the western Wrangellia minerals assessment area (presentation): Alaska Miners Association 24th Biennial Mining Conference, Fairbanks, Alaska April 7-13, 2014: Poster and Presentation Twelker, Evan and Burns, L.E., 2014, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 34 p
    Twelker, Evan, and Lande, Lauren, 2015, DGGS geological investigations in western Wrangellia (presentation): Alaska Miners Association Annual Convention, Anchorage, Alaska, November 1-5, 2015: Poster and Presentation Twelker, Evan and Lande, Lauren, 2015, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 45 p
    Twelker, Evan, and O'Sullivan, P.B., 2016, U-Pb zircon age data from meta-igneous rocks in the Clearwater Mountains, Mount Hayes A-6 Quadrangle, Alaska: Raw Data File RDF 2016-8, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 17 p
    Wypych, Alicja, Twelker, Evan, Freeman, L.K., Lande, Lauren, Newberry, R.J., Reioux, D.A., and Sicard, K.R., 2014, Major-oxide and trace-element geochemical data from rocks collected in 2014 in the Wrangellia mineral assessment area, Talkeetna Mountains C-4, C-3, and B-4 quadrangles, Alaska: Raw Data File RDF 2014-22, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 4 p
    Wypych, Alicja, Twelker, Evan, Freeman, L.K., Lande, Lauren, Newberry, R.J., Reioux, D.A., and Sicard, K.R., 2015, Major-oxide and trace-element geochemical data from rocks collected in 2015 in the Wrangellia mineral assessment area, Alaska: Raw Data File RDF 2015-16, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 4 p
    Wypych, Alicja, Twelker, Evan, Lande, L.L., and Newberry, R.J., 2015, Along-strike geochemical variations in the Late Triassic Nikolai magmatic system, Wrangellia, central Alaska (poster number V31D-3059): American Geophysical Union 2015 Fall Meeting, December 14-18, 2015: Poster and Presentation Wypych, Alicja and others, 2015, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 1 sheet

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

  1. How well have the observations been checked?
    Microprobe measurements were compared to standards of known composition were used to create a quantitative calibration. Calculated sums of reported elemental values are near 100 percent, indicating suitability for the investigation's scope.
  2. How accurate are the geographic locations?
    Location data were collected using Trimble Juno T5 GPS units. The devices have a reported error of about 10 m. Latitude and longitude are reported in 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
  2. What's the catalog number I need to order this data set? RI 2020-6
  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: 02-Oct-2020
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 Fri Oct 02 16:21:05 2020