Gillis, R.J. Benowitz, J.A. O'Sullivan, P.B. Layer, P.W. Wartes, M.A. 2017 report and digital data Raw Data File RDF 2017-7 Fairbanks, Alaska, United States Alaska Division of Geological & Geophysical Surveys 13 p. http://doi.org/10.14509/29750 This data release presents 40Ar/39Ar step-heating geochronology results from rocks collected roughly 7 km southwest of Contact Point, Iliamna B-3 Quadrangle. Samples obtained from a felsic dike intruding the principal Bruin Bay fault plane near Contact Point produced biotite and plagioclase 40Ar/39Ar ages of 36.5 +/- 0.8 Ma and 31.5+/-0.7 Ma, respectively. The age dates inform stratigraphic, structural, and geochronologic studies along the western margin of lower Cook Inlet basin. The accompanying report also presents zircon U-Pb LA-ICP-MS geochronology results for dikes near Ursus Head. The Energy Resources Group from the Alaska Division of Geological & Geophysical Surveys (DGGS) has conducted topical stratigraphic, structural, and geochronologic studies along the western margin of lower Cook Inlet basin since 2009 to improve knowledge of its Mesozoic geologic framework and help spur industry interest in this under-explored region of the petroleum basin. The publicly-available geological and geochronologic data augment state- and federally-funded geologic mapping along the basin margin performed since 2013. This report presents zircon U-Pb LA-ICP-MS and 40Ar/39Ar step-heating geochronology results for one mafic and two felsic dikes in the Iliamna B-3 and C-2 quadrangles at Ursus Head and near Contact Point, lower Cook Inlet. >summary-data-locations: Identification numbers, coordinates, sample descriptions, and summary ages of each sample >step-heating-data: Power output levels and resultant measurements from each sample run 2012 2017 ground condition complete None planned -154.053347 -154.053347 59.322150 59.322150 ISO 19115 Topic Category geoscientificInformation Alaska Division of Geological & Geophysical Surveys 40Ar/39Ar Age Dates Analyses Analyses and Sampling Analytical Lab Results Analytical Results Ar-Ar Bedrock Bedrock Geology Fault Displacement Geochronology Geologic Geology Igneous Isotopes Lab Methods Lead Methods Plagioclase Rocks Sample Location Stratigraphy Structural Geology Structure Tectonics U-Pb Uranium Volcanic Volcanic Rocks Zircon Alaska Division of Geological & Geophysical Surveys Contact Point Cook Inlet Cook Inlet Basin Iliamna Quadrangle Ursus Head Alaska Division of Geological & Geophysical Surveys Bruin Bay Fault Walker, J.D., Geissman, J.W., Bowring, S.A, and Babcock, L.E., comp., 2012, Geologic Time Scale v. 4.0: Geological Society of America Cenozoic Eocene Mesozoic Oligocene Triassic 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). 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. Alaska Division of Geological & Geophysical Surveys Metadata Manager mailing and physical

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Fairbanks AK 99709-3707 USA (907)451-5039 (907)451-5050 dggspubs@alaska.gov 8 am to 4:30 pm, Monday through Friday, except State holidays Lower Cook Inlet field studies in 2009 and 2012 were funded by the State of Alaska. We appreciate Pathfinder Aviation and pilot Merlin (Spanky) Handley for the helicopter support, Jack Barber at Alaska Air Taxi and Jose de Creeft at Northwind Aviation for charter fixed wing services, James and Shelia Isaak at Alaska Homestead Lodge, and Ray and Linda Williams at their lodge at Pile Bay for accommodations while performing field work. Lastly, we wish to thank Bob Swenson for drawing our attention to these spectacular outcrops, and who spent many hours pondering their significance. Betka, P.M. Gillis, R.J. 2014 Preliminary Interpretive Report PIR 2014-5 Fairbanks, Alaska, United States Alaska Division of Geological & Geophysical Surveys 14 p http://doi.org/10.14509/29130 Betka, P.M. Gillis, R.J. 2015 Preliminary Interpretive Report PIR 2015-5-2 Fairbanks, Alaska, United States Alaska Division of Geological & Geophysical Surveys p. 5-8 http://doi.org/10.14509/29457 Betka, P.M. Gillis, R.J. 2016 Preliminary Interpretive Report PIR 2016-1-10 Fairbanks, Alaska, United States Alaska Division of Geological & Geophysical Surveys p. 73-78 http://doi.org/10.14509/29544 Gillis, R.J. Wartes, M.A. O'Sullivan, P.B. 2011 Poster and Presentation Gillis, R.J. and others, 2011 Fairbanks, Alaska, United States Alaska Division of Geological & Geophysical Surveys 1 sheet http://doi.org/10.14509/23403 Gillis, R.J. Swenson, R.F. Wartes, M.A. Frohman, R.A. 2013 Preliminary Interpretive Report PIR 2013-1G Fairbanks, Alaska, United States Alaska Division of Geological & Geophysical Surveys p. 33-37 http://doi.org/10.14509/24850 This data set 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 the analytical values can be best answered by the originating lab. not applicable This data release is complete. Sample location coordinates (in NAD27 datum) were obtained using Garmin eTrex GPS units, with typical reported accuracy of about 9 ft. Fieldwork - Fresh, unweathered samples from surficial outcrops were collected by DGGS field geologists; samples were selected based on their cross-cutting relationships with structural features. 2012 Sample preparation and analysis - Before processing, samples were examined under binocular microscope, or thin sections were prepared and scrutinized to eliminate the possibility of analyzing altered mineral phases. Rock samples suitable for dating by 40Ar/39Ar geochronology analysis were submitted to the Geochronology Laboratory at the University of Alaska Fairbanks (UAF) where they were dated according to the protocols outlined in the accompanying report. Additional sample preparation details may be found in the accompanying report. 2012 point 0.000001 0.000001 decimal degrees North American Datum of 1927 Clarke 1866 6378206.40000000037 294.978698199999997 rdf2017-7-summary-data-locations.csv Identification numbers, coordinates, sample descriptions, and summary ages of each sample Alaska Division of Geological & Geophysical Surveys summary-data-locations SAMPLE Label assigned in the field to identify the sample. Alaska Division of Geological & Geophysical Surveys Generic example of a sample identifier: YYAAA9999X: YY=last two digits of year, AAA=geologist's 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. LAB_SAMPLE_NUMBER Label used by the lab to identify the sample. Alaska Division of Geological & Geophysical Surveys and Geochronology Laboratory at the University of Alaska Fairbanks (UAF) The lab sample number is typically identical to the field sample number. However, in some cases, the sample number provided by the lab does differ from the number assigned in the field. We provide both numbers to document instances in which the sample numbers in the lab files differ from the field sample number. COLLECTOR The geologist who collected the sample. Alaska Division of Geological & Geophysical Surveys The samples presented in this report were collected by the authors or other DGGS staff. LONGITUDE Longitude, NAD27 Alaska Division of Geological & Geophysical Surveys -154.053347 -154.053347 decimal degrees LATITUDE Latitude, NAD27 Alaska Division of Geological & Geophysical Surveys 59.32215 59.32215 decimal degrees DATED_MATERIAL Indicates the type of material that was used for analysis Alaska Division of Geological & Geophysical Surveys and Geochronology Laboratory at the University of Alaska Fairbanks (UAF) The type of material that was selected for dating varied according to mineral composition and grainsize of the submitted rock sample. This field specifies whether the age was derived from a mineral separate (generally 1 to 10 individual crystals dated together as a single run), a single crystal, or the whole rock. MINERAL Indicates the mineral that was used for analysis Alaska Division of Geological & Geophysical Surveys and Geochronology Laboratory at the University of Alaska Fairbanks (UAF) The minerals selected for dating would typically be grains of biotite, hornblende, or muscovite. DESCRIP_1 Description of the sample Alaska Division of Geological & Geophysical Surveys Characters 1 to 254 of a brief sample or station description. DESCRIP_2 Extension of the sample or station description for descriptions that are greater than 254 characters in length Alaska Division of Geological & Geophysical Surveys Characters greater than 254 of the sample or station description. NULL Blank (NULL) values indicate that the descriptive text is shorter than 254 characters. Alaska Division of Geological & Geophysical Surveys DESCRIP_3 Extension of the sample or station description for descriptions that are greater than 509 characters in length Alaska Division of Geological & Geophysical Surveys Characters greater than 509 of the sample or station description. NULL Blank (NULL) values indicate that the descriptive text is shorter than 509 characters. Alaska Division of Geological & Geophysical Surveys INTEGRATED_AGE_MA Integrated age and age error in million years Alaska Division of Geological & Geophysical Surveys and Geochronology Laboratory at the University of Alaska Fairbanks (UAF) The values are a concatenation of the integrated age determination and the calculated error associated with the integrated age determination PLATEAU_AGE_MA Plateau age and age error in million years Alaska Division of Geological & Geophysical Surveys and Geochronology Laboratory at the University of Alaska Fairbanks (UAF) The values are a concatenation of the plateau age determination and the calculated error associated with the plateau age determination PLATEAU_REMARKS Comments and additional values that pertain to the plateau age determination method or interpretation. Alaska Division of Geological & Geophysical Surveys and Geochronology Laboratory at the University of Alaska Fairbanks (UAF) Free text AGE_TYPE_PREFERRED Indicates the age type of the preferred age. Alaska Division of Geological & Geophysical Surveys and Geochronology Laboratory at the University of Alaska Fairbanks (UAF) A discussion of the preferred age for each analysis is provided in the accompanying lab report. The possible values are: plateau, isochron, weighted average, or integrated. PREFERRED_AGE The values are a concatenation of the preferred age determination and the calculated error associated with the preferred age determination Alaska Division of Geological & Geophysical Surveys and Geochronology Laboratory at the University of Alaska Fairbanks (UAF) The preferred age for each analysis is discussed in detail in the accompanying lab report. rdf2017-7-step-heating-data.csv Power output levels and resultant measurements from each sample run Alaska Division of Geological & Geophysical Surveys step-heating-data SAMPLE Label assigned in the field to identify the sample. Alaska Division of Geological & Geophysical Surveys Generic example of a sample identifier: YYAAA9999X: YY=last two digits of year, AAA=geologist's 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. LAB_SAMPLE_NUMBER Label used by the lab to identify the sample. Alaska Division of Geological & Geophysical Surveys and Geochronology Laboratory at the University of Alaska Fairbanks (UAF) The lab sample number is typically identical to the field sample number. However, in some cases, the sample number provided by the lab does differ from the number assigned in the field. We provide both numbers to document instances in which the sample numbers in the lab files differ from the field sample number. Laser_mW Laser output level in megawatts Geochronology Laboratory at the University of Alaska Fairbanks (UAF) 500 9001 megawatts NULL A NULL or blank values indicates that the values in the row were calculated by weighting the individual heating steps by the fraction of 39Ar released. Geochronology Laboratory at the University of Alaska Fairbanks (UAF) Integrated We indicate whether the values in the row were derived from a heating step or calculated by weighting the individual heating steps by the fraction of 39Ar released. Alaska Division of Geological & Geophysical Surveys NULL The values in the row were derived from a heating step Geochronology Laboratory at the University of Alaska Fairbanks (UAF) Integrated the values in this row were calculated by weighting the individual heating steps by the fraction of 39Ar released Alaska Division of Geological & Geophysical Surveys Cum39Ar Cumulative ratio of 39Argon released at this step Geochronology Laboratory at the University of Alaska Fairbanks (UAF) 0.004 1 NULL A NULL or blank values indicates that the value was not applicable or not calculated by the lab Geochronology Laboratory at the University of Alaska Fairbanks (UAF) Me40Ar39Ar Measured 40Ar/39Ar ratio for each heating step, corrected for blank and 39Ar decay Geochronology Laboratory at the University of Alaska Fairbanks (UAF) 6.44879 205.72829 Er40Ar39Ar The one sigma error for each 40Ar/39Ar measurement Geochronology Laboratory at the University of Alaska Fairbanks (UAF) 0.02538 14.46729 Me37Ar39Ar The ratio of measured 37Ar to measured 39Ar for each heating interval for each sample corrected for blank and 37Ar and 39Ar decay Geochronology Laboratory at the University of Alaska Fairbanks (UAF) -3.26021 43.47804 Er37Ar39Ar The one sigma error for each 37Ar/39Ar measurement Geochronology Laboratory at the University of Alaska Fairbanks (UAF) 0.06622 3.14452 Me36Ar39Ar Ratio of measured 36Ar to measured 39Ar for each step interval for each sample corrected for blank and 39Ar decay Geochronology Laboratory at the University of Alaska Fairbanks (UAF) -0.00444 0.6452 Er36Ar39Ar The one sigma error for each 36Ar/39Ar measurement Geochronology Laboratory at the University of Alaska Fairbanks (UAF) 0.00052 0.06899 Atm40Ar Percent of 40Ar which is atmospheric in composition at each step level Geochronology Laboratory at the University of Alaska Fairbanks (UAF) -16.25094 92.56205 ErAtm40Ar The one sigma error for the percent of 40Ar which is atmospheric in composition at each step level Geochronology Laboratory at the University of Alaska Fairbanks (UAF) 1.1149 32.93658 MeCaK Ratio of Calcium to Potassium as determined from 37Ar/39Ar Geochronology Laboratory at the University of Alaska Fairbanks (UAF) -5.96829 82.30332 ErCaK The one sigma error for each Ca/K determination Geochronology Laboratory at the University of Alaska Fairbanks (UAF) 0.12518 5.76981 MeClK Ratio of Chlorine to Potassium as determined from 38Ar/39Ar Geochronology Laboratory at the University of Alaska Fairbanks (UAF) -0.00052 0.12966 ErClK The one sigma error for each Cl/K determination Geochronology Laboratory at the University of Alaska Fairbanks (UAF) 0.00015 0.01173 Ar40Rad39ArK Ratio of radiogenic 40Ar to 39Ar derived from potassium Geochronology Laboratory at the University of Alaska Fairbanks (UAF) 3.33032 15.33344 Er40ArRad39ArK One sigma error for each 40ArRad/39ArK value Geochronology Laboratory at the University of Alaska Fairbanks (UAF) 0.15544 15.45416 AgeMa Calculated age for each temperature step for each sample Geochronology Laboratory at the University of Alaska Fairbanks (UAF) 18.32 69.17 MA ErAgeMa One sigma error of the age determination of each heating step Geochronology Laboratory at the University of Alaska Fairbanks (UAF) 0.75 68.4 MA WeightedAverageOfJFromStandards J value, calculated from the weighted average of standards placed in various positions in the nuclear reactor Geochronology Laboratory at the University of Alaska Fairbanks (UAF) WeightedAverageOfJFromStandards value and error Alaska Division of Geological & Geophysical Surveys Metadata Manager mailing and physical

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Fairbanks AK 99709-3707 USA (907)451-5039 (907)451-5050 dggspubs@alaska.gov 8 am to 4:30 pm, Monday through Friday, except State holidays RDF 2017-7 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. DGGS publications are available as free online downloads or you may purchase paper hard-copies or digital files on CD/DVD or other digital storage media by mail, phone, fax, or email from the DGGS Fairbanks office. To purchase this or other printed reports and maps, contact DGGS by phone (907-451-5020), e-mail (dggspubs@alaska.gov), or fax (907-451-5050). Payment accepted: Cash, check, money order, VISA, or MasterCard. Turnaround time is 1-2 weeks unless special arrangements are made and an express fee is paid. Shipping charge will be the actual cost of postage and will be added to the total amount due. Contact us for the exact shipping amount. Contact DGGS for current pricing ASCII tabular files http://doi.org/10.14509/29750 Free download 20170830 Alaska Division of Geological & Geophysical Surveys Metadata Manager mailing and physical

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Fairbanks AK 99709-3707 USA (907)451-5039 (907)451-5050 dggspubs@alaska.gov 8 am to 4:30 pm, Monday through Friday, except State holidays FGDC Content Standard for Digital Geospatial Metadata FGDC-STD-001-1998 If the user has modified the data in any way they are obligated to describe the types of modifications they have performed in the supporting metadata file. User specifically agrees not to imply that changes they made were approved by the Alaska Department of Natural Resources or Division of Geological & Geophysical Surveys. http://www.dggs.alaska.gov/metadata/dggs.ext dggs metadata extensions