Metadata: Identification_Information: Citation: Citation_Information: Originator: Layer, P.W. Originator: Solie, D.N. Publication_Date: 200811 Title: 40Ar/39Ar ages from the Selawik A-2, A-3 and A-4 and Candle B-5 quadrangles, Alaska Geospatial_Data_Presentation_Form: tabular digital data Series_Information: Series_Name: Raw Data File Issue_Identification: RDF 2008-5 Publication_Information: Publication_Place: Fairbanks, Alaska - USA Publisher: State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys Other_Citation_Details: 14 p. Online_Linkage: http://dx.doi.org/10.14509/17861 Description: Abstract: 40Ar/39Ar data from seven plutonic samples and one metamorphic sample collected during mineral assessment studies in 1991 show that various rock units in the Selawik Hills plutonic complex were emplaced in the order syenite/monzonite (nonfoliated, 106.6 ± 0.8 Ma; foliated, 101.7 ± 0.7 Ma; both on hornblende), followed by nepheline syenite (103.7 ± 0.8 Ma on hornblende) and then quartz monzonite (100.4 ± 3.7 Ma on biotite). 40Ar/39Ar data from Granite Mountain hornblendes yielded ages slightly older, but overlapping, those from Selawik Hills. In this suite, the silica-undersaturated phase appears to be younger (105.7 ±0.8 Ma) than the silica-saturated phase(s) (106.8 ± 0.8 Ma and 107.1 ± 0.8 Ma). Purpose: In 1991, the Alaska Division of Geological & Geophysical Surveys (DGGS) conducted helicopter-supported field work in west-central Alaska as part a state-wide project to review selected areas of federal land that were eligible at the time for selection by Alaska to become state land. DGGSs role in the project was to evaluate mineral resource potential in the eligible units of land by acquiring data to outline permissive mineral terranes and to define mineral deposit types that could occur in each land selection unit (DGGS Staff, 1992). The data in this report resulted from investigations in the Selawik Hills and Granite Mountain areas as part of the land selection project. Geochemical and major oxide data (Solie and others, 1993a) and electron microprobe data (Solie and others, 1993b) were previously published. A brief discussion of our 40Ar/39Ar results from the Selawik Hills was presented at a Geological Society of America meeting (Solie and Layer, 1993). The purpose of this DGGS Raw Data File (RDF) is to present all our 40Ar/39Ar results from the Selawik Hills and Granite Mountain and make them available for use. Supplemental_Information: Attribute information for the following tables (entities) is included in this metadata file under the "Entity_and_Attribution_Information" section: >Locations_Results_AnalyticalData coordinates of sample locations, 40Ar/39Ar age summary, analytical data (Tables 1, 2, 3) Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 1991 Currentness_Reference: observed Status: Progress: Complete Maintenance_and_Update_Frequency: None planned Spatial_Domain: Bounding_Coordinates: West_Bounding_Coordinate: -161.5744 East_Bounding_Coordinate: -159.8142 North_Bounding_Coordinate: 66.17045 South_Bounding_Coordinate: 65.40369 Keywords: Theme: Theme_Keyword_Thesaurus: None Theme_Keyword: 40Ar/39Ar Theme_Keyword: Age Dates Theme_Keyword: Analytical Results Theme_Keyword: Ar-Ar Theme_Keyword: Geochronology Theme_Keyword: Granite Theme_Keyword: Hornblende Theme_Keyword: Igneous Rocks Theme_Keyword: Plutonic Rocks Place: Place_Keyword_Thesaurus: None Place_Keyword: Granite Mountain Place_Keyword: Candle Quadrangle Place_Keyword: Selawik Quadrangle Temporal: Temporal_Keyword_Thesaurus: None Temporal_Keyword: Cretaceous Temporal_Keyword: Albian Temporal_Keyword: Early Cretaceous Temporal_Keyword: Mesozoic Access_Constraints: This report 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. 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. Point_of_Contact: Contact_Information: Contact_Organization_Primary: Contact_Organization: State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys Contact_Position: GIS Data Manager/Cartographer Contact_Address: Address_Type: mailing and physical Address: 3354 College Road City: Fairbanks State_or_Province: AK Postal_Code: 99709-3707 Contact_Voice_Telephone: (907) 451-5029 Contact_Voice_Telephone: (907) 451-5020 Contact_Facsimile_Telephone: (907) 451-5050 Contact_Electronic_Mail_Address: dggspubs@alaska.gov Contact_Instructions: You may view our web site at http://www.dggs.alaska.gov for the latest information on available data. Please e-mail your questions and data requests when possible since our web site and e-mail address will remain current even if our phone number and mailing address change. Data_Set_Credit: This research was supported by State funding to the Alaska Division of Geological & Geophysical Surveys. Additional Acknowledgments: members of the 1991 DGGS field teams: Thomas K. Bundtzen, Rainer J. Newberry, Greg M. Laird, Ellen E. Harris, Milt A. Wiltse, Jeffrey T. Kline, Thomas E. Smith, Shirley A. Liss and Karen H. Clautice. Review of draft manuscript by D.J. Szumigala. Data_Quality_Information: Attribute_Accuracy: Attribute_Accuracy_Report: All field locations were visually determined by the geologists in the field and recorded on a 1:63,360 topographic map. Coordinates were digitized visually from the field maps. DGGS submitted eight rock samples to the UAF Geochronology Laboratory for 40Ar/39Ar dating; three were collected from Granite Mountain in the Candle B-5 quadrangle and four were collected from the Selawik Hills in the Selawik quadrangle. Major oxide and selected trace element analyses for some of the samples are included in Solie and others (1993a). Separates for 40Ar/39Ar dating were prepared to >99.5 percent purity (visual inspection) using standard heavy liquid and magnetic separation techniques followed by hand-picking under a binocular microscope. Thin section examination of the samples prior to crushing indicated that the chosen minerals were free from alteration and sufficiently coarse-grained for mechanical separation. For all minerals, grains in the size range of 250 - 500 microns were used. For each sample, ~50-80 mg of biotite or 250-350 mg of hornblende or whole rock (phenocryst-free groundmass) was packaged in an aluminum foil tube and irradiated in position 5C at the McMaster University nuclear reactor, in Hamilton, Ontario. Approximately 20 samples were irradiated at a time. Six packages containing ~20 mg of the standard mineral mmhb-1 (Samson and Alexander, 1987) with an age of 513.9 Ma (Lanphere and others, 1990) were also irradiated with the samples to determine the irradiation parameter (J) and the flux gradient in the reactor. Samples and standards were analyzed 45 to 90 days after irradiation. The irradiated samples were step-heated on-line in a Modifications Ltd. low-blank furnace. Temperature control was better than 5 degrees and a maximum temperature in excess of 1600o C was achievable to ensure complete sample fusion. The extracted argon was purified in a two-stage process using a liquid nitrogen cold finger and two SAES Zr-Al getters. Prior to measurement of the Ar, the gas was collected on an activated charcoal finger. The purified Ar gas was measured using a Nuclide 6-60-SGA 15 cm mass spectrometer. The sensitivity of the spectrometer is 6.5 x 10-15 mol/mV and system noise is generally around 0.02 mV. System blanks are generally better than 1 X 10-14 mol for 40Ar. Argon isotopic measurements for both samples and standards were corrected for the system blanks, for decay of 37Ar and 39Ar, and for reactor-induced isotopic interferences. Ages were calculated using the equations and corrections from McDougall and Harrison (1999) and the constants from Steiger and Jaeger (1977). Age, Ca/K and Cl/K spectra plots are shown in figure 3, and analytical age data are shown in Tables 2 and 3. All errors on analyses are reported at the 1-sigma level. For each mass spectrometer analysis, five Ar isotope abundances are measured. 36Ar is used to determine the amount of atmospheric or initial Ar in the sample, 37Ar provides an estimation of the Ca content in the mineral, 38Ar provides an estimation of the Cl content, 39Ar reflects the K content and 40Ar is a mixture of initial and radiogenic Ar. The age of the sample is proportional to the ratio of the amount of radiogenic 40Ar to the amount of 39Ar produced by neutron bombardment from 40K. All samples were dated by the 40Ar/39Ar step-heating method. In this method, a sample is heated to progressively higher temperatures in a double-vacuum resistance-heated furnace, and the argon isotopes are measured and age determined for each step (fraction). The integrated age is the age given by the total gas measured in all fractions and is equivalent to a potassium-argon (K-Ar) age. The fractions are commonly plotted on an age spectrum plot for analysis. A spectrum provides a plateau age if three or more consecutive gas fractions represent at least 50% of the total gas release and are within two standard deviations of each other (Mean Square Weighted Deviation less than ~2.5). If the fractions do not meet the criteria for a plateau due to intrafraction scatter in ages, then a weighted mean age of plateau-like fractions, with each fraction weighted by the volume of 39Ar released, is calculated. Logical_Consistency_Report: No topologic relationships are present in the data. Completeness_Report: This dataset includes all of the samples submitted for 40Ar/39Ar age date analyses from the Selawik and Candle quadrangle which were collected by DGGS during the summer of 1991. Hand samples and thin sections are no longer available for the samples dated. The brief sample descriptions in text are compiled from field notes and some preliminary petrographic notes from 1991. Positional_Accuracy: Horizontal_Positional_Accuracy: Horizontal_Positional_Accuracy_Report: Sample locations were determined visually by geologist in the field, using a brunton compass and altimeter and topographic map. Locations were then digitized visually from the field maps using ArcGIS v9.2. Quantitative_Horizontal_Positional_Accuracy_Assessment: Horizontal_Positional_Accuracy_Value: 100 Horizontal_Positional_Accuracy_Explanation: The sample locations were found in the field using a compass and altimeter. Considering the errors inherent in the USGS topographic maps, locating oneself in the field, and the methods of digitizing stations, samples are located to an accuracy of between 10 and 100 meters. Lineage: Source_Information: Source_Citation: Citation_Information: Originator: Lanphere, M.A. Originator: Dalrymple, G.B. Originator: Fleck, R.J. Originator: Pringle, M.S. Publication_Date: 1990 Title: Intercalibration of mineral standards for K/Ar and 40Ar/39Ar age measurements Geospatial_Data_Presentation_Form: journal article Series_Information: Series_Name: EOS Transactions of the American Geophysical Union Issue_Identification: v. 71 Other_Citation_Details: (abstract), P. 1658 Type_of_Source_Media: paper Source_Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 1990 Source_Currentness_Reference: publication date Source_Citation_Abbreviation: Lanphere and others, 1990 Source_Contribution: Describes intercalibration standards Source_Information: Source_Citation: Citation_Information: Originator: McDougall, Ian Originator: Harrison, T.M. Publication_Date: 1999 Title: Geochronology and Thermochronology by the 40Ar/39Ar method Edition: 2 Geospatial_Data_Presentation_Form: book chapter Publication_Information: Publication_Place: Oxford Publisher: Oxford University Press Other_Citation_Details: 269 pp Type_of_Source_Media: paper Source_Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 1999 Source_Currentness_Reference: publication date Source_Citation_Abbreviation: McDougall and others, 1999 Source_Contribution: Source reference for equations and corrections used in age calculation. Source_Information: Source_Citation: Citation_Information: Originator: Samson, S.D. Originator: Alexander, E.C. Publication_Date: 1987 Title: Calibration of the interlaboratory 40Ar/39Ar dating standard, MMhb-1 Geospatial_Data_Presentation_Form: journal article Series_Information: Series_Name: Chemical Geology Issue_Identification: v. 66 Other_Citation_Details: p.27-34 Type_of_Source_Media: paper Source_Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 1987 Source_Currentness_Reference: publication date Source_Citation_Abbreviation: Samson and Alexander, 1987 Source_Contribution: Interlaboratory calibration data for age determination Source_Information: Source_Citation: Citation_Information: Originator: Steiger, R.H. Originator: Jager, E Publication_Date: 1977 Title: Subcommission on geochronology: convention on the use of decay constants in geo- and cosmochronology Geospatial_Data_Presentation_Form: journal article Series_Information: Series_Name: Earth and Planetary Science Letters Issue_Identification: v.36 Other_Citation_Details: p. 359-363 Type_of_Source_Media: paper Source_Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 1977 Source_Currentness_Reference: publication date Source_Citation_Abbreviation: Steiger and Jager, 1977 Source_Contribution: discussion of use of decay constants in age determination Source_Information: Source_Citation: Citation_Information: Originator: Solie, D.N. Originator: Harris, E.E. Originator: Bundtzen, T.K. Originator: Wiltse, M.A. Originator: Newberry, R.J. Originator: Kline, J.T. Originator: Smith, T.E. Publication_Date: 199303 Title: Land Selection Unit 16 (Selawik, Candle, Norton Bay, Unalakleet, Kateel River, and Nulate quadrangles): references,DGGS sample locations, geochemical and major oxide data Geospatial_Data_Presentation_Form: document Series_Information: Series_Name: Public Data File Issue_Identification: PDF 93-16a Publication_Information: Publication_Place: Fairbanks AK Publisher: Alaska Division of Geological & Geophysical Surveys Other_Citation_Details: 54 p. Type_of_Source_Media: paper Source_Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 1993 Source_Currentness_Reference: observed Source_Citation_Abbreviation: Solie and others, 1993a Source_Contribution: geochemical and major oxide data from study area Source_Information: Source_Citation: Citation_Information: Originator: Solie, D.N. Originator: Severin, K.P. Originator: Lear, K.G. Publication_Date: 199305 Title: Electron microprobe data from Selawik Hills and Granite Mountain plutonic rocks, western Alaska Geospatial_Data_Presentation_Form: document Series_Information: Series_Name: Public Data File Issue_Identification: PDF 93-16b Publication_Information: Publication_Place: Fairbanks AK Publisher: Alaska Division of Geological & Geophysical Surveys Other_Citation_Details: 11 p. Type_of_Source_Media: paper Source_Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 1993 Source_Currentness_Reference: observed Source_Citation_Abbreviation: Solie and others, 1993b Source_Contribution: electron microprobe data from rocks in study area Source_Information: Source_Citation: Citation_Information: Originator: Solie, D.N. Originator: Layer, P.W. Publication_Date: 1993 Title: Evidence of synmagmatic foliation in the Selawik Hills, NW Alaska, based on 40Ar/39Ar age determinations Geospatial_Data_Presentation_Form: document Series_Information: Series_Name: Geological Society of America Abstracts with Programs Issue_Identification: v.25, no.5 Other_Citation_Details: abstract, p.149. Type_of_Source_Media: paper Source_Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 1993 Source_Currentness_Reference: observed Source_Citation_Abbreviation: Solie and Layer, 1993 Source_Contribution: preliminary presentation of age results Process_Step: Process_Description: Fieldwork - Alaska Division of Geological & Geophysical Surveys (DGGS) conducted helicopter-supported field work in west-central Alaska as part a state-wide project to review selected areas of federal land that were eligible at the time for selection by Alaska to become state land. Rock samples were collected in the Selawik Hills and Granite Mountain areas during summer 1991. Members of the field crew were Diana N. Solie, Thomas K. Bundtzen, Rainer J. Newberry, Greg M. Laird, Ellen E. Harris, Milt A. Wiltse, Jeffrey T. Kline, Thomas E. Smith, Shirley A. Liss and Karen H. Clautice.Geochemical and major oxide data from samples collected during the Selawik Hills project were published (Solie and others, 1993a). Selected electron microprobe data from rocks collected from Selawik Hills and Granite Mountain were published in Solie and others, 1993b. A brief discussion of the 40Ar/39Ar age results was given in an abstract by Solie and Layer (1993). Source_Used_Citation_Abbreviation: Solie and others, 1993a Source_Used_Citation_Abbreviation: Solie and others, 1993b Source_Used_Citation_Abbreviation: Solie and Layer, 1993 Process_Date: 199107 Process_Step: Process_Description: Labwork - Separates for 40Ar/39Ar dating were prepared to >99.5 percent purity (visual inspection) using standard heavy liquid and magnetic separation techniques followed by hand-picking under a binocular microscope. Thin section examination of the samples prior to crushing indicated that the chosen minerals were free from alteration and sufficiently coarse-grained for mechanical separation. For all minerals, grains in the size range of 250 - 500 microns were used. For each sample, ~50-80 mg of biotite or 250-350 mg of hornblende or whole rock (phenocryst-free groundmass) was packaged in an aluminum foil tube and irradiated in position 5C at the McMaster University nuclear reactor, in Hamilton, Ontario. Approximately 20 samples were irradiated at a time. Six packages containing ~20 mg of the standard mineral mmhb-1 (Samson and Alexander, 1987) with an age of 513.9 Ma (Lanphere and others, 1990) were also irradiated with the samples to determine the irradiation parameter (J) and the flux gradient in the reactor. Samples and standards were analyzed 45 to 90 days after irradiation. The irradiated samples were step-heated on-line in a Modifications Ltd. low-blank furnace. Temperature control was better than 5 degrees and a maximum temperature in excess of 1600o C was achievable to ensure complete sample fusion. The extracted argon was purified in a two-stage process using a liquid nitrogen cold finger and two SAES Zr-Al getters. Prior to measurement of the Ar, the gas was collected on an activated charcoal finger. The purified Ar gas was measured using a Nuclide 6-60-SGA 15 cm mass spectrometer. The sensitivity of the spectrometer is 6.5 x 10-15 mol/mV and system noise is generally around 0.02 mV. System blanks are generally better than 1 X 10-14 mol for 40Ar. Argon isotopic measurements for both samples and standards were corrected for the system blanks, for decay of 37Ar and 39Ar, and for reactor-induced isotopic interferences. Ages were calculated using the equations and corrections from McDougall and Harrison (1999) and the constants from Steiger and Jaeger (1977). All errors on analyses are reported at the 1-sigma level. For each mass spectrometer analysis, five Ar isotope abundances are measured. 36Ar is used to determine the amount of atmospheric or initial Ar in the sample, 37Ar provides an estimation of the Ca content in the mineral, 38Ar provides an estimation of the Cl content, 39Ar reflects the K content and 40Ar is a mixture of initial and radiogenic Ar. The age of the sample is proportional to the ratio of the amount of radiogenic 40Ar to the amount of 39Ar produced by neutron bombardment from 40K. Source_Used_Citation_Abbreviation: Samson and Alexander, 1987 Source_Used_Citation_Abbreviation: Lanphere and others, 1990 Source_Used_Citation_Abbreviation: McDougall and Harrison, 1999 Source_Used_Citation_Abbreviation: Steiger and Jaeger, 1977 Process_Date: 1991 Spatial_Data_Organization_Information: Direct_Spatial_Reference_Method: Point Spatial_Reference_Information: Horizontal_Coordinate_System_Definition: Planar: Grid_Coordinate_System: Grid_Coordinate_System_Name: Universal Transverse Mercator Universal_Transverse_Mercator: UTM_Zone_Number: 4 Transverse_Mercator: Scale_Factor_at_Central_Meridian: 9.9996 Longitude_of_Central_Meridian: -153.000 Latitude_of_Projection_Origin: 0 False_Easting: 500000 False_Northing: 0 Planar_Coordinate_Information: Planar_Coordinate_Encoding_Method: coordinate pair Coordinate_Representation: Abscissa_Resolution: 1 Ordinate_Resolution: 1 Planar_Distance_Units: meters Planar_Coordinate_Layer_Name: Locations_Results_AnalyticalData Geodetic_Model: Horizontal_Datum_Name: North American Datum of 1927 Ellipsoid_Name: Clarke 1866 Semi-major_Axis: 6378206.4 Denominator_of_Flattening_Ratio: 294.978698 Entity_and_Attribute_Information: Detailed_Description: Entity_Type: Entity_Attribute_Layer_Name: Locations_Results_AnalyticalData Entity_Type_Label: Table1_coordinates.csv Entity_Type_Definition: Coordinates for 40Ar/39Ar samples Entity_Type_Definition_Source: Alaska Division of Geological & Geophysical Surveys Attribute: Attribute_Label: SampleNo Attribute_Definition: Items in the Sample Number field Attribute_Definition_Source: Alaska Division of Geological & Geophysical Surveys Attribute_Domain_Values: Unrepresentable_Domain: Sample numbers are unique identifiers derived from the last two digits of the year the sample was collected, initials of the geologist's name who collected it, and the consecutively numbered station location. If more than one sample was collected from the station location, each is assigned a letter (a, b, c, etc) designator as well. Attribute: Attribute_Label: Easting Attribute_Definition: UTM easting coordinate, Zone 4, NAD 27 Attribute_Definition_Source: Alaska Division of Geological & Geophysical Surveys Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: 394311 Range_Domain_Maximum: 463220 Attribute_Units_of_Measure: m Attribute: Attribute_Label: Northing Attribute_Definition: UTM northing coordinate, Zone 4, NAD 27 Attribute_Definition_Source: Alaska Division of Geological & Geophysical Surveys Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: 7255163 Range_Domain_Maximum: 7339612 Attribute_Units_of_Measure: m Attribute: Attribute_Label: Latitude Attribute_Definition: Latitude coordinate, NAD 27 Attribute_Definition_Source: Alaska Division of Geological & Geophysical Surveys Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: 65.40369 Range_Domain_Maximum: 66.17045 Attribute_Units_of_Measure: decimal degree Attribute: Attribute_Label: Longitude Attribute_Definition: Longitude coordinate, NAD27 Attribute_Definition_Source: Alaska Division of Geological & Geophysical Surveys Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: 159.81421 Range_Domain_Maximum: 161.57441 Attribute_Units_of_Measure: decimal degree Detailed_Description: Entity_Type: Entity_Attribute_Layer_Name: Locations_Results_AnalyticalData Entity_Type_Label: Table2_agesummary.csv Entity_Type_Definition: Summary table for 40Ar/39Ar data Entity_Type_Definition_Source: Alaska Division of Geological & Geohysical Surveys Attribute: Attribute_Label: Min. Attribute_Definition: Material used for age date Attribute_Definition_Source: Alaska Division of Geological & Geophysical Surveys Attribute_Domain_Values: Unrepresentable_Domain: Material used for dating. Includes Bio (biotite) or Hbd (hornblende). Attribute: Attribute_Label: Integrated Age (Ma) Attribute_Definition: Integrated age in million years, Attribute_Definition_Source: Alaska Division of Geological & Geophysical Surveys Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: 98.8+-0.7 Range_Domain_Maximum: 107.4+-0.8 Attribute_Units_of_Measure: Ma Attribute: Attribute_Label: Plateau Age Attribute_Definition: Summarizes the Plateau (P) Age or the Weighted Mean (W) Age in Million years for each sample Attribute_Definition_Source: Alaska Division of Geological & Geophysical Surveys Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: 100.4+-3.7 Range_Domain_Maximum: 107.1+-0.8 Attribute_Units_of_Measure: Ma Attribute: Attribute_Label: Plateau Information Attribute_Definition: Summarizes number of fractions, percent 39Ar released and MSWD for each sample Attribute_Definition_Source: Alaska Division of Geological & Geophysical Surveys Attribute_Domain_Values: Unrepresentable_Domain: # of fractions, % 39Ar released, MSWD for each sample Attribute: Attribute_Label: SampleName Attribute_Definition: Items in the Sample Name field Attribute_Definition_Source: Alaska Division of Geological & Geophysical Surveys Attribute_Domain_Values: Unrepresentable_Domain: Sample numbers are unique identifiers derived from the last two digits of the year the sample was collected, initials of the geologist's name who collected it, and the consecutively numbered station location. If more than one sample was collected from the station location, each is assigned a letter (a, b, c, etc) designator as well. Attribute: Attribute_Label: Rock type Attribute_Definition: name of rock type of sample Attribute_Definition_Source: Alaska Division of Geological & Geophysical Surveys Attribute_Domain_Values: Unrepresentable_Domain: rock type, either a type of plutonic rock or a generalized metamorphic rock Attribute: Attribute_Label: Mass Attribute_Definition: mass of sample that was dated, in grams Attribute_Definition_Source: Alaska Division of Geological & Geophysical Surveys Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: 0.0605 Range_Domain_Maximum: 0.3588 Attribute_Units_of_Measure: grams Attribute: Attribute_Label: # Attribute_Definition: number of fractions in the step heat Attribute_Definition_Source: Alaska Division of Geological & Geophysical Surveys Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: 9 Range_Domain_Maximum: 12 Attribute_Units_of_Measure: each Attribute: Attribute_Label: K2O Attribute_Definition: Weight % K2O as estimated from 39Ar release Attribute_Definition_Source: Alaska Division of Geological & Geophysical Surveys Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: 0.72 Range_Domain_Maximum: 7.15 Attribute_Units_of_Measure: weight % Attribute: Attribute_Label: CaO Attribute_Definition: weight % CaO estimated from 37Ar release Attribute_Definition_Source: Alaska Division of Geological & Geophysical Surveys Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: 0.64 Range_Domain_Maximum: 15.37 Attribute_Units_of_Measure: weight % Attribute: Attribute_Label: Isochron age Attribute_Definition: Isochron age and intial 40Ar/36Ar, both calculated from regression of isotopic compositions of individual step-heated fractions. Initial is the intercept of regression line. Attribute_Definition_Source: Alaska Division of Geological & Geophysical Surveys Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: 101.6+-0.8 Range_Domain_Maximum: 107.1+-0.8 Attribute_Units_of_Measure: Ma Detailed_Description: Entity_Type: Entity_Attribute_Layer_Name: Locations_Results_AnalyticalData Entity_Type_Label: Table3_analytical data.csv Entity_Type_Definition: For each sample, the 40Ar/39Ar analytical data associated with each temperature recorded is presented. Entity_Type_Definition_Source: Alaska Division of Geological & Geophysical Surveys Attribute: Attribute_Label: Temp Attribute_Definition: Temperature in Degrees C of step for which data were recorded Attribute_Definition_Source: Alaska Division of Geological & Geophysical Surveys Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: 400 Range_Domain_Maximum: 1600 Attribute_Units_of_Measure: Degrees C Attribute: Attribute_Label: Cum. 39Ar Attribute_Definition: Cumulative 39Argon Attribute_Definition_Source: Alaska Division of Geological & Geophysical Surveys Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: 0.0000 Range_Domain_Maximum: 1.0000 Attribute: Attribute_Label: 40Ar/39Ar measured Attribute_Definition: Measured 40Ar/39Ar ratio at each heating step, corrected for blank and 39Ar decay Attribute_Definition_Source: Alaska Division of Geological & Geophysical Surveys Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: 0.0001 Range_Domain_Maximum: 634.0000 Attribute: Attribute_Label: +/- Attribute_Definition: Defines the size of the error bars for each ratio measurement to one standard deviation Attribute_Definition_Source: Alaska Division of Geological & Geophysical Surveys Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: 0.0000 Range_Domain_Maximum: 509.0000 Attribute: Attribute_Label: 37Ar/39Ar measured Attribute_Definition: The ratio of 37Ar to 39Ar measured at each temperature interval for each sample corrected for blank and 37Ar and 39Ar decay Attribute_Definition_Source: Alaska Division of Geological & Geophysical Surveys Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: 0.00000 Range_Domain_Maximum: 23.00000 Attribute: Attribute_Label: 36Ar/39Ar Attribute_Definition: Ratio of amounts of 36Ar to 39Ar measured at each temperature interval for each sample corrected for blank and 39Ar decay Attribute_Definition_Source: Alaska Division of Geological & Geophysical Surveys Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: 0.0000 Range_Domain_Maximum: 3.2000 Attribute: Attribute_Label: % Atm. 40Ar Attribute_Definition: Percent of 40Ar which is atmospheric in composition Attribute_Definition_Source: Alaska Division of Geological & Geophysical Surveys Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: 0.0 Range_Domain_Maximum: 150.0 Attribute: Attribute_Label: Ca/K Attribute_Definition: ratio of Calcium to Potassium as determined from 37Ar/39Ar Attribute_Definition_Source: Alaska Division of Geological & Geophysical Surveys Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: 0.0000 Range_Domain_Maximum: 43.0000 Attribute: Attribute_Label: Cl/K Attribute_Definition: ration of Chloring to Potassium as determined from 38Ar/39Ar Attribute_Definition_Source: Alaska Division of Geological & Geophysical Surveys Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: 0.00000 Range_Domain_Maximum: 0.15000 Attribute: Attribute_Label: 40Ar*/39ArK Attribute_Definition: ratio of radiogenic 40Ar to 39Ar derived from potassium Attribute_Definition_Source: Alaska Division of Geological & Geophysical Surveys Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: 0.0000 Range_Domain_Maximum: 12.0000 Attribute: Attribute_Label: Age (Ma) Attribute_Definition: calculated age for each temperature step for each sample Attribute_Definition_Source: Alaska Division of Geological & Geophysical Surveys Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: 0.0 Range_Domain_Maximum: 185.0 Attribute_Units_of_Measure: Ma Attribute: Attribute_Label: +-(Ma) Attribute_Definition: Defines the size of the error bars for each measurement to one standard deviation Attribute_Definition_Source: Alaska Division of Geological & Geophysical Surveys Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: 0.2 Range_Domain_Maximum: 3167.0 Attribute_Units_of_Measure: Ma Distribution_Information: Distributor: Contact_Information: Contact_Organization_Primary: Contact_Organization: State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys Contact_Position: Natural Resource Technician Contact_Address: Address_Type: mailing and physical Address: 3354 College Road City: Fairbanks State_or_Province: AK Postal_Code: 99709-3707 Country: USA Contact_Voice_Telephone: 907-451-5020 Contact_TDD/TTY_Telephone: None available. Contact_Facsimile_Telephone: 907-451-5050 Contact_Electronic_Mail_Address: dggspubs@alaska.gov Hours_of_Service: 8 am to 4:30 pm, Monday through Friday, except State holidays Contact_Instructions: Please view our Web site (http://www.dggs.alaska.gov) for the latest information on available data. Please contact us using the e-mail address provided above when possible. Resource_Description: Raw-Data File Distribution_Liability: The State of Alaska makes no express or implied warranties (including warranties of merchantability and fitness) with respect to the character, function, or capabilities of the electronic services 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, any failure thereof, or otherwise, and in no event will the State of Alaska's liability to the requester or anyone else exceed the fee paid for the electronic service or product. Standard_Order_Process: Non-digital_Form: Current publication is available on paper. 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. Fees: Printed publication can be purchased (contact information below) plus shipping if mailed. Turnaround: Two weeks unless special arrangements are made and an express fee is paid. Standard_Order_Process: Digital_Form: Digital_Transfer_Information: Format_Name: PDF Format_Version_Number: 1.6 File_Decompression_Technique: No compression applied Digital_Transfer_Option: Online_Option: Computer_Contact_Information: Network_Address: Network_Resource_Name: http://www.dggs.alaska.gov/pubs/ Fees: Digital files on CD-ROM are available (contact information below). Scanned images of these products may be viewed online or downloaded for free from the DGGS Web site. Ordering_Instructions: Order by phone (907-451-5020), e-mail (dggspubs@alaska.gov), or fax (907-451-5050). Payment accepted: Cash, check, money order, VISA, or MasterCard. Metadata_Reference_Information: Metadata_Date: 20081031 Metadata_Contact: Contact_Information: Contact_Organization_Primary: Contact_Organization: State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys Contact_Position: Metadata Manager Contact_Address: Address_Type: mailing and physical address Address: 3354 College Road City: Fairbanks State_or_Province: AK Postal_Code: 99709-3707 Country: USA Contact_Voice_Telephone: 907-451-5039 Contact_Facsimile_Telephone: 907-451-5050 Contact_Electronic_Mail_Address: dggspubs@alaska.gov Hours_of_Service: 8 am to 4:30 pm, Monday through Friday, except State holidays. Contact_Instructions: Please contact us through the e-mail address above whenever possible. Metadata_Standard_Name: FGDC Content Standard for Digital Geospatial Metadata Metadata_Standard_Version: FGDC-STD-001-1998 Metadata_Access_Constraints: none Metadata_Use_Constraints: 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 State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys.