Zircon U-Pb ages of the Valdez Group and the Passage Canal and Billings plutons from the Passage Canal area of Prince William Sound, Alaska

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Frequently anticipated questions:


What does this data set describe?

Title:
Zircon U-Pb ages of the Valdez Group and the Passage Canal and Billings plutons from the Passage Canal area of Prince William Sound, Alaska
Abstract:
Zircon U-Pb ages of the Valdez Group and the Passage Canal and Billings plutons from the Passage Canal area of Prince William Sound, Alaska, Raw Data File 2024-29, provides zircon U-Pb results from samples collected in conjunction with geologic mapping of the Passage Canal area near Whittier, Alaska. These analyses help constrain the ages of major mapped bedrock units (Bull and others, 2024). The rock units include Cretaceous Valdez Group marine strata and the Passage Canal and Billings plutons. These data and report are available from the DGGS website: http://doi.org/10.14509/31427.
Supplemental_Information:
geochron-data:    Analytical lab data	
geochron-summary:    Identification numbers, coordinates, sample descriptions, and summary ages of each sample
  1. How might this data set be cited?
    Gillis, R.J., O'Sullivan, P.B., and Donelick, R.A., 2024, Zircon U-Pb ages of the Valdez Group and the Passage Canal and Billings plutons from the Passage Canal area of Prince William Sound, Alaska: Raw Data File RDF 2024-29, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 13 p.
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -148.850420
    East_Bounding_Coordinate: -148.492420
    North_Bounding_Coordinate: 60.868810
    South_Bounding_Coordinate: 60.802600
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 2012
    Ending_Date: 2024
    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 0.0000001. Longitudes are given to the nearest 0.0000001. Latitude and longitude values are specified in decimal degrees. The horizontal datum used is NAD27.
      The ellipsoid used is Clarke 1866.
      The semi-major axis of the ellipsoid used is 6378206.4.
      The flattening of the ellipsoid used is 1/294.9786982.
  7. How does the data set describe geographic features?
    rdf2024-29-UPb-data.zip, rdf2024-29-UPb-data-dictionary.xlsx
    Analytical lab data (Source: DGGS, see report for additional detail)
    rdf2024-29-UPb-summary-data.xlsx, rdf2023-15-geochron-summary-data-dictionary.csv
    Identification numbers, coordinates, sample descriptions, and summary ages of each sample (Source: DGGS, see report for additional detail)

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?
    We thank Pathfinder Aviation and pilot Spanky Handley for their exceptional work in difficult circumstances and the people of Whittier for their kindness and generosity. We greatly appreciate the Chugach Alaska Native Corporation and the U.S. Forest Service for their helpfulness and access to their lands during this study. These analyses were funded by the 2012 U.S. Geological Survey National Cooperative Geologic Mapping Program, award number G12AS00007. 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?

The city of Whittier, Alaska (pop. ~250), is one of only two all-weather, ice-free ports that serve the Alaska mainland via both railroad and road access. The city lies about 100 km by road southeast of Anchorage near the head of Passage Canal, a deep fjord in western Prince William Sound. The geologic mapping supports informed community planning, mitigation, and emergency response in and around this high-risk community and its associated critical infrastructure.

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: 2012 (process 1 of 2)
    Sample collection - We selected approximately 10-15 kg of the freshest, most unaltered and unweathered rock available at each of three sampled locations. Sample 12BG300A was a medium- to fine-grained sandstone metamorphosed to greenschist facies. Samples 12BG303A and 12BG308A were phaneritic intrusive rocks with unaltered mafic mineral phases, visible striae on crystal faces, and appeared to be free of chloritic alteration or oxidation. Sample locations were recorded using modern, hand-held GPS units set to UTM Zone 6 (NAD27) coordinates with typical horizontal precision of 9 to 21 feet. Locations presented herein were converted to NAD27 geographic coordinates.
    Date: 2023 (process 2 of 2)
    Zircon U-Pb LA-ICP-MS analysis - Zircon grains were isolated and prepared for Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS) analyses. Zircon U-Pb data were acquired for LA-ICP-MS analysis at Donelick Properties in Viola, Washington, using a Resonetics RESOlution M-50 ArF Excimer 193 nm laser attached to an Agilent 7700x quadrupole inductively coupled plasma mass spectrometer. Maximum depositional ages (MDA) defined by populations of young zircons were determined for the Valdez Group sample. All weighted-mean calculations, and weighted mean, Concordia, and kernel density estimate plots were determined and produced using IsoplotR. Maximum depositional ages (MDA) defined by populations of young zircons were determined for the Valdez Group sample. To determine its MDA, we calculated the youngest statistical population (YSP). To determine the crystallization age of the igneous rocks we used the commonly adopted method of calculating the WM of the entire zircon distribution, recognizing that the resulting mean standard weighted deviation (MSWD) is much greater than 1.0 and the probability of fits of zero indicates dispersion of dates greater than expected for a genetically congruent population.
  3. What similar or related data should the user be aware of?
    Freeman, L.K., Montayne, Simone, and Wypych, Alicja, 2017, Major-oxide and trace-element geochemical data from rocks collected near Panorama Mountain, Mile 104 Seward Highway, Crow Pass, and Whittier, Alaska: Raw Data File RDF 2017-12, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 4 p
    Hubbard, T.D., Wolken, G.J., Stevens, D.S.P., and Combellick, R.A., 2013, High-resolution lidar data for the Whittier area, Passage Canal, and Portage Lake, Alaska: Raw Data File RDF 2013-3, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 5 p
    Nicolsky, D.J., Suleimani, E.N., Combellick, R.A., and Hansen, R.A., 2011, Tsunami inundation maps of Whittier and western Passage Canal, Alaska: Report of Investigation RI 2011-7, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 65 p., 4 sheets, scale 1:14,000
    Nicolsky, D.J., Wolken, G.J., Combellick, R.A., and Hansen, E., 2011, APPENDIX B: Potential rockfall-generated tsunami at Whittier, Alaska: Report of Investigation RI 2011-7A, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: p. 57-65
    Nicolsky, D.J., and Suleimani, E.N., 2018, Potential maximum permanent flooding, Whittier, Alaska: Report of Investigation RI 2011-7B, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 1 sheet, scale 1:6,500
    Wolken, G.J., and Balazs, M.S., 2014, Inventory and preliminary assessment of geologic hazards in the Passage Canal-Portage Valley area, south-central Alaska: Preliminary Interpretive Report PIR 2014-1, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 15 p

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

  1. How well have the observations been checked?
    Rock and outcrop descriptions at field stations presented herein are reconnaissance observations and interpretations made by project geologists in the field. The accompanying report provides a comprehensive bibliographic reference list of prior work identifying and delineating rock units and structural elements and a more comprehensive summary of the analytical methods. When applicable, errors are reported in the data tables. This data set is being released into 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 about the analytical values or procedures can be best answered by the originating lab.
  2. How accurate are the geographic locations?
    Sample locations were recorded using modern, hand-held GPS units set to UTM Zone 6 (NAD27) coordinates with typical horizontal precision of 9 to 21 feet. Locations presented herein were converted to NAD27 geographic coordinates.
  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 2024-29
  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: 30-Oct-2024
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 Oct 30 19:38:43 2024