U-Pb zircon age data from meta-igneous rocks in the Clearwater Mountains, Mount Hayes A-6 Quadrangle, Alaska

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What does this data set describe?

Title:
U-Pb zircon age data from meta-igneous rocks in the Clearwater Mountains, Mount Hayes A-6 Quadrangle, Alaska
Abstract:
We report U-Pb zircon geochronology results for one metavolcanic and one metaplutonic rock sample from the Mount Hayes A-6 Quadrangle of central Alaska. These samples are representative of rock units assigned to the Clearwater terrane of Jones and others (1987), a sequence of greenschist-grade metavolcanic and metasedimentary rocks of poorly constrained age and tectonic origin. Our results indicate a crystallization age of 277.33 +/- 11.84 Ma for a felsic metavolcanic rock, and a 268.05 +/- 11.64 Ma crystallization age for a granitic metaplutonic unit intruding the former.
Supplemental_Information: 
border:    Outline of the study area.
geochron-data:    Geochronology lab files and applicable documentation.
geochron-summary:    Identification numbers, coordinates, sample descriptions, and summary ages of each sample.
  1. How should this data set be cited?

    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.

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -146.935839
    East_Bounding_Coordinate: -146.854469
    North_Bounding_Coordinate: 63.220292
    South_Bounding_Coordinate: 63.192897

  3. What does it look like?

  4. Does the data set describe conditions during a particular time period?

    Beginning_Date: 2013
    Ending_Date: 2016
    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 1/298.257223563.

  7. How does the data set describe geographic features?

    rdf2016-8-border.shp
    Outline of the study area. (Source: Alaska Division of Geological & Geophysical Surveys (DGGS))

    rdf2016-8-geochron-data
    Geochronology lab files and applicable documentation. (Source: Alaska Division of Geological & Geophysical Surveys (DGGS))

    rdf2016-8-geochron-summary.csv
    Identification numbers, coordinates, sample descriptions, and summary ages of each sample. (Source: Alaska Division of Geological & Geophysical Surveys (DGGS))

    SAMPLE
    Label assigned in the field to identify the sample. (Source: Alaska Division of Geological & Geophysical Surveys)

    Generic example of a sample identifier: YYYYAAA9999X: YYYY= four digits of year, AAA=geologist's initials (one to three characters), 999=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.

    LAB_SAMPLE_NUMBER
    Label used by the lab to identify the sample. (Source: Alaska Division of Geological & Geophysical Surveys and Apatite to Zircon, Inc. (A2Z))

    free text

    LATITUDE
    Latitude, WGS84 (Source: Alaska Division of Geological & Geophysical Surveys)

    Range of values
    Minimum:63.196506
    Maximum:63.216682
    Units:decimal degrees

    LONGITUDE
    Longitude, WGS84 (Source: Alaska Division of Geological & Geophysical Surveys)

    Range of values
    Minimum:-146.927846
    Maximum:-146.862468
    Units:decimal degrees

    DESCRIPTION
    Description of the sample (Source: Alaska Division of Geological & Geophysical Surveys)

    A brief sample and/or station description.

    NUM_MEASUREMENTS_USED
    Number of measurements used for calculating the age. (Source: Apatite to Zircon, Inc. (A2Z))

    Range of values
    Minimum:13
    Maximum:35

    TOTAL_MEASUREMENTS
    Total number of measurements. (Source: Apatite to Zircon, Inc. (A2Z))

    Range of values
    Minimum:27
    Maximum:45

    WMEAN_AGE_MA
    Weighted mean age, in millions of years (Ma). (Source: Apatite to Zircon, Inc. (A2Z))

    Range of values
    Minimum:268.05
    Maximum:277.33
    Units:Ma

    MEAN_AGE_MA
    Mean age, in millions of years (Ma). (Source: Apatite to Zircon, Inc. (A2Z))

    Range of values
    Minimum:266.04
    Maximum:277.17
    Units:Ma

    S2_FFER
    2-sigma error + fractionation-factor error (Source: Apatite to Zircon, Inc. (A2Z))

    Range of values
    Minimum:11.64
    Maximum:11.84

    S2_STDEV_FFER
    2-sigma standard deviation on the 2-sigma error + fractionation-factor error (Source: Apatite to Zircon, Inc. (A2Z))

    Range of values
    Minimum:8.76
    Maximum:13.48

    S2
    2-sigma error (not including fractionation factor error) (Source: Apatite to Zircon, Inc. (A2Z))

    Range of values
    Minimum:1.3
    Maximum:2.46

    S2_STDEV
    2-sigma standard deviation on the 2-sigma error (not including fractionation factor error) (Source: Apatite to Zircon, Inc. (A2Z))

    Range of values
    Minimum:1.48
    Maximum:3.74

    MSWDW
    Mean Square of Weighted Deviates. Lower value indicates decreasing scatter in the data. This is, roughly, a measure of the ratio of the observed scatter of the points (from the best-fit line) to the expected scatter (from the assigned errors and error correlations). The MSWD parameter cannot be compared to the classical R2 parameter, and is not a measure of how highly correlated the X- and Y-values are. If the assigned errors are the only cause of scatter, the MSWD will tend to be near unity. MSWD values much greater than unity generally indicate either underestimated analytical errors, or the presence of non-analytical scatter. MSWD values much less than unity generally indicate either overestimated analytical errors or unrecognized error-correlations. (Source: Apatite to Zircon, Inc. (A2Z))

    Range of values
    Minimum:1.56
    Maximum:3.08

    P_MSWDW
    Statistical scatter in the MSWD - values range between 1 (good) and 0 (poor) (Source: Apatite to Zircon, Inc. (A2Z))

    Range of values
    Minimum:0.001013
    Maximum:0.149818

    MEAN_U_PPM
    Mean concentration of uranium (U), in parts per million (ppm). (Source: Apatite to Zircon, Inc. (A2Z))

    Range of values
    Minimum:777.66
    Maximum:2613.82

    MEAN_TH_PPM
    Mean concentration of thorium (Th), in parts per million (ppm). (Source: Apatite to Zircon, Inc. (A2Z))

    Range of values
    Minimum:219.76
    Maximum:1261.44

    MEAN_U_TH_RATIO_PPM
    Mean concentration of uranium (U) divided by the mean concentration of thorium (Th); in parts per million (ppm). (Source: Apatite to Zircon, Inc. (A2Z))

    Range of values
    Minimum:2.072
    Maximum:3.539

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 project was supported by State of Alaska Capital Improvement Project funds through the Strategic and Critical Minerals Assessment program (part of the Airborne Geological/Geophysical Mineral Inventory [AGGMI]). Ray and Margaret Donelick (A2Z) provided technical assistance with sample preparation and LA-ICP-MS data collection.

  3. To whom should users address questions about the data?

    Alaska Division of Geological & Geophysical Surveys
    GIS Manager
    3354 College Rd
    Fairbanks, AK 99709-3707
    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?

The metamorphic rocks of the Clearwater terrane form an alleged tectonostratigraphic terrane approximately 2 by 10 km in extent in the northwestern corner of the Mount Hayes A-6 Quadrangle. Based on limited fossil evidence, the terrane has been variously interpreted as a structurally-bound fragment of a Late Triassic volcanic arc or potentially a window into middle to late Paleozoic metamorphic basement underlying Wrangellia. We applied U-Pb zircon geochronology to two samples of meta-igneous rocks to resolve the uncertainty surrounding the precise age and regional correlations of this terrane.

How was the data set created?

  1. From what previous works were the data drawn?

    Jones, D.L. and others, 1987 (source 1 of 1)
    Jones, D.L., Silberling, N.J., Coney, P.J., and Plafker, George, 1987, Lithotectonic terrane map of Alaska (west of the 141st meridian): Miscellaneous Field Studies Map MF 1874-A, U.S. Geological Survey, United States.

    Online Links:

    Other_Citation_Details: 1 sheet, scale 1:2,500,000
    Type_of_Source_Media: paper
    Source_Scale_Denominator: 2500000
    Source_Contribution: fieldwork

  2. How were the data generated, processed, and modified?

    Date: 2013 (process 1 of 2)
    Fieldwork - DGGS field geologists collected rock samples from the ground surface; care was taken to collect fresh, unweathered samples representative of rock types in the map area. Locations were recorded using handheld GPS units with an estimated horizontal accuracy of approximately 10 m.

    Data sources used in this process:

    • Jones, D.L. and others, 1987

    Date: 2014 (process 2 of 2)
    U-pb data analysis - LA-ICP-MS sample preparation and data collection was performed at the A2Z laboratory in Viola, Idaho. The accompanying report provides a description of laboratory procedures and applicable references.

  3. What similar or related data should the user be aware of?

    Burns, L.E., CGG, and Fugro GeoServices, Inc., 2014, Wrangellia survey area: Airborne magnetic and electromagnetic data in line (point), grid, vector, and map formats, Talkeetna Mountains, Healy, and Mt. Hayes quadrangles, south-central Alaska: Geophysical Report GPR 2014-1, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 56 sheets, 1 DVD, scale 1:63,360
    Clautice, K.H., Smith, T.E., Pessel, G.H., and Solie, D.N., 1989, Geology and mineral occurrences, upper Clearwater Creek area, Mt. Hayes A-6 Quadrangle, Alaska: Public Data File PDF 89-18, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 14 p., 2 sheets, scale 1:24,000
    Werdon, M.B., Azain, J.S., and Granitto, Matthew, 2014, Reanalysis of historical U.S. Geological Survey sediment samples for geochemical data from the western part of the Wrangellia terrane, Anchorage, Gulkana, Healy, Mt. Hayes, Nabesna, and Talkeetna Mountains quadrangles, Alaska: Raw Data File RDF 2014-5, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 6 p

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

  1. How well have the observations been checked?

    This data is being released in the DGGS Raw Data File series. The information has been examined by several geologists familiar with the study area, but the data and accompanying report have not been formally reviewed for technical content or for conformity to the editorial standards of DGGS. Questions regarding the accuracy of information in the the A2Z data files can be best answered by the originating lab.

  2. How accurate are the geographic locations?

    Locations were recorded using handheld, WAAS-enabled GPS devices. WAAS-enabled GPS devices have a reported error of about 1 m (NSTB/WAAS T&E Team, 2006). Depending on degradation of the WAAS and GPS signals, the horizontal position error of sample locations in this report is in the range of 1-10 m.

  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
    3354 College Road
    Fairbanks, AK 99709-3707
    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 2016-8

  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: 13-May-2016
Metadata author:
Alaska Division of Geological & Geophysical Surveys
Metadata Manager
3354 College Road
Fairbanks, AK 99709-3707
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 2.9.21 on Fri May 13 16:11:25 2016