Rock-Eval pyrolysis, vitrinite reflectance, and kerogen microscopy analytical results from Eocene to Pliocene strata in the Susitna Basin, Kenai Peninsula, and Kachemak Bay, Cook Inlet, Alaska

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Frequently anticipated questions:

What does this data set describe?

Title:
Rock-Eval pyrolysis, vitrinite reflectance, and kerogen microscopy analytical results from Eocene to Pliocene strata in the Susitna Basin, Kenai Peninsula, and Kachemak Bay, Cook Inlet, Alaska
Abstract:
Rock-Eval pyrolysis, vitrinite reflectance, and kerogen microscopy analytical results from Eocene to Pliocene strata in the Susitna Basin, Kenai Peninsula, and Kachemak Bay, Cook Inlet, Alaska, Raw Data File 2025-31, provides analytical results from Rock-Eval pyrolysis, vitrinite reflectance, and kerogen microscopy performed on 51 outcrop samples collected across the Cook Inlet region, including the Susitna Basin, Kenai Peninsula, and Kachemak Bay. These samples were obtained during DGGS Energy Resources Section field campaigns conducted in 2006, 2007, and 2009 to evaluate regional geology and hydrocarbon potential. Eight samples were analyzed by Rock-Eval pyrolysis, and vitrinite reflectance and kerogen microscopy were completed for the full sample set. The samples represent five stratigraphic units: six from the West Foreland Formation, six from the Hemlock Conglomerate, 18 from the Tyonek Formation, 15 from the Beluga Formation, and six from the Sterling Formation. Rock-Eval pyrolysis supports assessment of hydrocarbon-generative potential and thermal maturity. Vitrinite reflectance and kerogen microscopy provide complementary indicators of organic matter type and thermal evolution. Together, these datasets contribute to a more comprehensive understanding of source rock characteristics and maturation history within the Cook Inlet petroleum system. 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/10.14509/31800.
Supplemental_Information: 
Rock-Eval data:    Table of identification numbers, coordinates, station and sample descriptions, Rock-Eval analytical results, and an accompanying data dictionary.	
Vitrinite reflectance data:    Table of identification numbers, coordinates, station and sample descriptions, vitrinite reflectance  analytical results, and an accompanying data dictionary.	
Visual kerogen  data:    Table of identification numbers, coordinates, station and sample descriptions, visual kerogen  analytical results, and an accompanying data dictionary.
  1. How might this data set be cited?
    Qureshi, K.A., Inc., Baseline Resolution, and Laboratories, Weatherford, 2025, Rock-Eval pyrolysis, vitrinite reflectance, and kerogen microscopy analytical results from Eocene to Pliocene strata in the Susitna Basin, Kenai Peninsula, and Kachemak Bay, Cook Inlet, Alaska: Raw Data File RDF 2025-31, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 64 p.
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -152.032280
    East_Bounding_Coordinate: -150.807655
    North_Bounding_Coordinate: 61.386305
    South_Bounding_Coordinate: 59.442888
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 2006
    Ending_Date: 2009
    Currentness_Reference:
    ground condition
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: spreadsheet
  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 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?
    rdf2025_31_rock-eval-data.csv, rdf2025_31_rock-eval-data-dictionary.csv
    Table of identification numbers, coordinates, station and sample descriptions, Rock-Eval analytical results, and an accompanying data dictionary. (Source: DGGS)
    rdf2025_31_visual-kerogen-data.csv, rdf2025_31_visual-kerogen-data-dictionary.csv
    Table of identification numbers, coordinates, station and sample descriptions, vitrinite reflectance analytical results, and an accompanying data dictionary. (Source: DGGS)
    rdf2025_31_vitrinite-reflectance-data.csv, rdf2025_31_vitrinite-reflectance-data-dictionary.csv
    Table of identification numbers, coordinates, station and sample descriptions, visual kerogen analytical results, and an accompanying data dictionary. (Source: 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?
    Capital Improvement Projects funded the DGGS Cook Inlet Basin Analysis Program from the State of Alaska. Benchmark Oil and Gas, Pioneer Natural Resources Alaska, Inc., and Chevron North America Exploration and Production Company generously provided additional support. We gratefully thank the Cook Inlet Region Incorporation (CIRI), Tyonek Native Corporation, and the Kenai National Wildlife Refuge for permitting land access. We thank the field geologists who collected most of the samples used in this study, Simone Montayne for her assistance with data compilation, and Erin Campbell for her review.
  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?

This data release supports evaluation of source rock quality and thermal maturity in the Cook Inlet region by providing new geochemical and organic petrology analyses. These data strengthen Alaska's regional resource assessments, reduce exploration uncertainty, and inform energy-related decisions that contribute to the state's long-term economic and energy security.

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 collection - DGGS field geologists collected samples from surface outcrops for Rock-Eval pyrolysis, vitrinite reflectance, and kerogen microscopy analyses. Sample location coordinates were obtained using recreational-grade GPS units, with a typical reported accuracy of about 10 meters. Coordinates were collected using the NAD27 datum. Coordinate conversion was performed from NAD27 to NAD83 using ArcGIS Pro. Each sample number corresponds to the measured section number and the sample position (meters above base of section) within each measured section. Coordinates refer to the base of the measured section
    Date: 2009 (process 2 of 2)
    Sample analysis - Eight outcrop samples were sent to Weatherford Laboratories in Houston, Texas, for Rock-Eval pyrolysis analysis. The samples analyzed include coal, carbonaceous mudstone, and siltstone. Thirty-two outcrop samples were sent to Baseline Resolution, Inc. in Shenandoah, Texas and 19 to Weatherford Laboratories in Houston, Texas. The labs employed standardized methods for vitrinite reflectance analysis of coal and dispersed vitrinite in sedimentary rocks, following ASTM protocols D2798-11a and D7708-14 (2015). Vitrinite reflectance samples were also evaluated using kerogen microscopy, also known as visual kerogen analysis. Additional details on laboratory methods and data reduction are provided in the accompanying report.
  3. What similar or related data should the user be aware of?
    Finzel, E.S., Gillis, R.J., Ridgway, K.D., and LePain, D.L., 2009, Preliminary evaluation of basin margin exhumation and provenance of Cenozoic strata, Chuitna and Beluga rivers area, Cook Inlet forearc basin, Alaska: Preliminary Interpretive Report PIR 2009-4, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 16 p
    Freeman, L.K., Gillis, R.J., Elliott, B.A., and Wypych, Alicja, 2016, Major-oxide and trace-element geochemical data from rocks collected in 2010 in the Tyonek Quadrangle, Alaska: Raw Data File RDF 2016-5, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 2 p
    Gillis, R.J., Benowitz, J.A., O'Sullivan, P.B., Layer, P.W., and Wartes, M.A., 2017, Zircon U-Pb and 40Ar/39Ar results from dikes collected within the Bruin Bay fault zone, lower Cook Inlet: Raw Data File RDF 2017-7, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 14 p
    Gillis, R.J., 2013, Overview of 2012 field studies: Upper Alaska Peninsula and west side of lower Cook Inlet, Alaska: Preliminary Interpretive Report PIR 2013-1, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 48 p
    Gillis, R.J., 2014, Cook Inlet program 2013 field studies: Observations and preliminary interpretations from new 1:63,360-scale geologic mapping of the Iniskin Peninsula, lower Cook Inlet, Alaska: Preliminary Interpretive Report PIR 2014-2, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 31 p
    Gillis, R.J., LePain, D.L., Ridgway, K.D., and Finzel, E.S., 2009, A reconnaissance view of an unnamed fault near Capps Glacier, northwestern Cook Inlet basin, and its potential as a regional-scale, basin-controlling structure: Preliminary Interpretive Report PIR 2009-3, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 9 p
    Gillis, R.J., Wartes, M.A., Herriott, T.M., LePain, D.L., Benowitz, J.A., Wypych, Alicja, Donelick, R.A., O'Sullivan, P.B., and Layer, P.W., 2022, 40Ar/39Ar and U-Pb geochronology of Cretaceous-Paleocene igneous rocks and Cenozoic strata of northwestern Cook Inlet, Alaska: Linkages between arc magmatism, cooling, faulting, and forearc subsidence: Professional Report PR 125 v. 1.1, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 78 p
    Gregersen, L.S., and Shellenbaum, D.P., 2016, Top Mesozoic unconformity subcrop map, Cook Inlet basin, Alaska: Report of Investigation RI 2016-4, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 1 sheet, scale 1:500,000
    Helmold, K.P., LePain, D.L., Wilson, M.D., and Peterson, C.S., 2013, Petrology and reservoir potential of Tertiary and Mesozoic sandstones, Cook Inlet, Alaska: A preliminary analysis of outcrop samples collected during 2007-2010 field seasons: Preliminary Interpretive Report PIR 2013-5, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 34 p
    Herriott, T.M., and Wartes, M.A., 2014, Geologic-mapping-based observations of the Middle Jurassic Chinitna Formation and Upper Jurassic Naknek Formation in the Tilted Hills, Iniskin Peninsula, Cook Inlet, Alaska: Preliminary Interpretive Report PIR 2014-3, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 23 p
    Herriott, T.M., and Wartes, M.A., 2017, Discovery of a 35-meter-thick, oil-stained sandstone interval in outcrop of the Tonnie Siltstone Member, Chinitna Formation, lower Cook Inlet, south-central Alaska: Preliminary Interpretive Report PIR 2017-5, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 12 p
    Herriott, T.M., 2016, Petroleum-related geologic studies in lower Cook Inlet during 2015, Iniskin-Tuxedni region, south-central Alaska: Preliminary Interpretive Report PIR 2016-1, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 78 p
    Herriott, T.M., Nye, C.J., Reger, R.D., Wartes, M.A., LePain, D.L., and Gillis, R.J., 2014, Geologic context, age constraints, and sedimentology of a Pleistocene volcaniclastic succession near Mount Spurr volcano, south-central Alaska: Report of Investigation RI 2014-2, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 35 p
    Herriott, T.M., Wartes, M.A., and Decker, P.L., 2017, Deep-water canyons and sequence-stratigraphic framework of the Upper Jurassic Naknek Formation, south-central Alaska: Report of Investigation RI 2017-4, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 53 p
    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
    Hickey, J.J., Wilson, M.D., and Reifenstuhl, R.R., 2007, Petrographic study of 50 samples from the Tertiary sandstone of Cook Inlet, Alaska: potential tight gas reservoirs: Report of Investigation RI 2007-2, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 64 p
    LePain, D.L., 2009, Preliminary results of recent geologic investigations in the Homer-Kachemak Bay area, Cook Inlet basin: Progress during the 2006-2007 field season: Preliminary Interpretive Report PIR 2009-8, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 187 p
    LePain, D.L., Lillis, P.G., Helmold, K.P., and Stanley, R.G., 2012, Migrated hydrocarbons in exposure of Maastrichtian nonmarine strata near Saddle Mountain, lower Cook Inlet, Alaska: Report of Investigation RI 2012-1, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 13 p
    LePain, D.L., Stanley, R.G., and Helmold, K.P., 2020, Deepwater mass-transport complex in the Upper Jurassic Pomeroy Arkose Member, Naknek Formation, Chinitna Bay, Alaska: The depositional record of co-genetic slumps and debris flows in a slope to proximal basin floor setting: Report of Investigation RI 2020-5, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 31 p
    Loveland, A.M., and Associates, PetroTech, 2013, Mercury injection capillary pressure results from outcrop samples in the Indecision Creek Member of the Naknek Formation and the Kaguyak Formation type section: Raw Data File RDF 2013-1, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 4 p
    Loveland, A.M., and Associates, PetroTech, 2013, Mercury injection capillary pressure (MICP) results from outcrop samples in the Tyonek, Beluga, and West Foreland formations, Tyonek and Talkeetna quadrangles, Alaska: Raw Data File RDF 2013-4, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 5 p
    Loveland, A.M., and Associates, PetroTech, 2013, Mercury injection capillary pressure (MICP) results from outcrop samples in the Naknek Formation, Iniskin Peninsula, Alaska: Raw Data File RDF 2013-6, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 10 p
    Loveland, A.M., and Associates, PetroTech, 2014, Mercury injection capillary pressure results from outcrop samples in the Kaguyak, Naknek, and West Foreland formations, Iniskin Peninsula region, Alaska: Raw Data File RDF 2014-1, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 5 p
    Reger, R.D., 2009, Reinterpretation of the Kaloa deposits near Granite Point, northwestern Cook Inlet, Alaska: Preliminary Interpretive Report PIR 2009-2, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 8 p
    Rosenthal, J.L., Betka, P.M., Gillis, R.J., and Nadin, E.S., 2018, Fracture intensity of the Mesozoic sedimentary forearc strata of lower Cook Inlet, Alaska: Report of Investigation RI 2018-4, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 38 p
    Shellenbaum, D.P., Gregersen, L.S., and Delaney, P.R., 2010, Top Mesozoic unconformity depth map of the Cook Inlet basin, Alaska: Report of Investigation RI 2010-2, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 1 sheet, scale 1:500,000
    Wartes, M.A., 2015, Energy-related studies during the 2014 field season, western Cook Inlet, Alaska: Preliminary Interpretive Report PIR 2015-5, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 62 p
    Wypych, Alicja, Gillis, R.J., Betka, P.M., and Decker, P.L., 2016, Major-oxide and trace-element geochemical data from rocks collected in 2015 in lower Cook Inlet, Iniskin - Tuxedni region, Alaska: Raw Data File RDF 2016-3, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 2 p
    Zippi, P.A., and Loveland, A.M., 2012, Palynological analysis of 228 outcrop samples from the Kenai, Seldovia, and Tyonek quadrangles, Cook Inlet region, Alaska: Raw Data File RDF 2012-1, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 10 p
    Zippi, P.A., Gillis, R.J., Montayne, Simone, and Loveland, A.M., 2021, Palynological and thermal maturity analysis of outcrop samples from the Kenai, Seldovia, and Tyonek quadrangles, Cook Inlet region, Alaska: Raw Data File RDF 2021-8, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 4 p

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

  1. How well have the observations been checked?
    The accompanying report and data tables provide a comprehensive discussion of processing methods, with errors reported in the tables where applicable. This data is being released as part of the DGGS RDF series, which includes content describing approved techniques and methods for the collection, storage, visualization, analysis, and interpretation of scientific data. While the information has been reviewed by several geologists familiar with the study area, the data and report have not undergone formal review for technical content or conformity to DGGS editorial standards. For inquiries regarding analytical values or procedures, the originating lab is the best point of contact.
  2. How accurate are the geographic locations?
    Sample location coordinates were obtained using recreational-grade GPS units, with a typical reported accuracy of about 10 meters. Coordinates were collected using the NAD27 datum. Coordinate conversion was performed from NAD27 to NAD83 using ArcGIS Pro. Each sample number corresponds to the measured section number and the sample position (meters above base of section) within each measured section. Coordinates refer to the base of the measured section.
  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 2025-31
  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: 29-Dec-2025
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 Mon Dec 29 18:14:36 2025