Detrital zircon maximum depositional dates for the Jurassic Chinitna and Naknek Formations, lower Cook Inlet, Alaska: A preliminary view

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What does this data set describe?

Title:
Detrital zircon maximum depositional dates for the Jurassic Chinitna and Naknek Formations, lower Cook Inlet, Alaska: A preliminary view
Abstract:
This report and it's accompanying analytical data present uranium-lead (U-Pb) detrital zircon dates for the Paveloff Siltstone Member of the Chinitna Formation and the lower sandstone member of the Naknek Formations, permitting insights into the depositional ages of these units and revealing discrepancies between this new geochronology and the long-established biostratigraphy and/or the current geologic time scale. We conducted laser ablation-inductively coupled plasma mass spectrometry (LA-ICPMS) U-Pb detrital zircon geochronology of two sandstone samples from Oil Bay in Cook Inlet, Alaska. Samples were prepared and analyzed by GeoSep Services. All files are available from the DGGS website: <http://doi.org/10.14509/30180>.
Supplemental_Information:
geochron-data: Geochronology lab files and applicable documentation.
  1. How should this data set be cited?

    Herriott, T.M., Wartes, M.A., O'Sullivan, P.B., and Gillis, R.J., 2019, Detrital zircon maximum depositional dates for the Jurassic Chinitna and Naknek Formations, lower Cook Inlet, Alaska: A preliminary view: Preliminary Interpretive Report PIR 2019-5, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 11 p.

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -153.28048
    East_Bounding_Coordinate: -153.27545
    North_Bounding_Coordinate: 59.66939
    South_Bounding_Coordinate: 59.66258

  3. What does it look like?

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

    Beginning_Date: 2010
    Ending_Date: 2019
    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 0.0001. Longitudes are given to the nearest 0.0001. Latitude and longitude values are specified in decimal degrees.

      The horizontal datum used is North American Datum of 1983.
      The ellipsoid used is GRS 80.
      The semi-major axis of the ellipsoid used is 6378137.
      The flattening of the ellipsoid used is 1/298.257222101000025.

  7. How does the data set describe geographic features?

    pir2019-5-geochron-data-09BG010-14.5c.xlsx, pir2019-5-geochron-data-09BG023a.xlsx, pir2019-5-geochron-data-documentation.xlsx
    Geochronology lab files and applicable documentation. (Source: this report)


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 State of Alaska funded this work. Merlin "Spanky" Handley safely transported our field crew to collect samples in Oil Bay. We thank Alaska Homestead Lodge for their hospitality. Discussions with Jamey Jones, Richard Lease, Matt Rioux, Jim Crowley, Mark Schmitz, and Mareca Guthrie improved this study. Kristen Janssen formatted this report, and Simone Montayne managed the metadata. Dave LePain and Mandy Willingham provided reviews that improved this paper.

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

    Alaska Division of Geological & Geophysical Surveys
    Metadata Manager
    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


Why was the data set created?

The Alaska Division of Geological & Geophysical Surveys leads a basin analysis program in Cook Inlet of south-central Alaska. This program aims to improve understanding of the region's petroleum geology and includes work in the Iniskin Bay-Tuxedni Bay area of lower Cook Inlet. A major focus of these studies is the Jurassic forearc stratigraphy, which hosts the basin's oil source rocks. Robust biostratigraphic constraints provide temporal context for this economically significant Jurassic succession. However, prior to this work, no modern radioisotopic dates were available to render absolute age control. Chronostratigraphy is an integral part of basin analysis, and geochronologic dates are commonly obtained to refine existing frameworks that have historically relied on paleontologic collections.


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: 2009 (process 1 of 2)
    Sample selection - DGGS field geologists collected fresh, unweathered, bulk interval samples from bedrock outcrops. See accompanying report for sample locations and descriptions.

    Date: 2018 (process 2 of 2)
    Data analysis - We conducted laser ablation-inductively coupled plasma mass spectrometry (LA-ICPMS) U-Pb detrital zircon geochronology of two sandstone samples from Oil Bay in Cook Inlet, Alaska. Samples were prepared and analyzed by GeoSep Services. Three maximum depositional dates were determined for each sample: youngest single grain; and youngest mode of the kernel density estimation. See accompanying report for additional discussion of analytical and statistical methodology.

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


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

  1. How well have the observations been checked?

    These data are being released in the DGGS Preliminary Interpretive Report series. This category is intended for the timely release of maps and reports with preliminary interpretation of geology or analytical data. The publication has undergone limited peer review but does not necessarily conform to DGGS editorial standards. Interpretations or conclusions contained in this publication are subject to change.

  2. How accurate are the geographic locations?

    Locations were measured using a recreational grade GPS. Note that location coordinates for sample 09BG010-14.5C (N59.66258° W153.27545° [NAD83]) are tied to the base of a measured section that lies 14.5 m stratigraphically below the sampled bed.

  3. How accurate are the heights or depths?

  4. Where are the gaps in the data? What is missing?

    This data release is complete but does not include comprehensive metadata for all of the analytical fields in the data tables. The data and limited metadata provided by the originating lab were deemed sufficiently understandable for the intent of this analysis, and attempts to obtain more comprehensive documentation from the lab were unsuccessful. Requests for additional information regarding the parameters and definitions of the analytical values should be directed to the originating lab.

  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 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
  2. What's the catalog number I need to order this data set?

    PIR 2019-5

  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: 17-Sep-2019
Metadata author:
Alaska Division of Geological & Geophysical Surveys
Attn: Simone Montayne
Metadata Manager
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
Metadata standard:
FGDC Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
Metadata extensions used:


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