Identification_Information: Citation: Citation_Information: Originator: Loewen, M.W. Originator: Wallace, K.L. Originator: Lubbers, Jordan Originator: Ruth, Dawn Originator: Izbekov, P.E. Originator: Larsen, J.F. Originator: Graham, Nathan Publication_Date: 2023 Title: Glass electron microprobe analyses methods, precision and accuracy for tephra studies in Alaska Geospatial_Data_Presentation_Form: csv Series_Information: Series_Name: Miscellaneous Publication Issue_Identification: MP 174 Publication_Information: Publication_Place: Fairbanks, Alaska, United States Publisher: Alaska Division of Geological & Geophysical Surveys Other_Citation_Details: 20 p. Online_Linkage: https://doi.org/10.14509/31045 Description: Abstract: Glass electron microprobe analyses methods, precision and accuracy for tephra studies in Alaska, Miscellaneous Publication 174, reports analytical conditions and secondary standard results for electron probe microanalysis (EPMA) of glass in support of tephra studies in Alaska between 2018 and 2023. Long-term accuracy and precision are evaluated for our standardized method and compared between analytical sessions and instruments at the University of Alaska Fairbanks (UAF) and the U.S. Geological Survey (USGS) Menlo Park, California. Future versions will provide updates with secondary standard results from future analytical sessions and any changes to the analytical routine and conditions. This data is released as a Miscellaneous Publication with an open end-user license. The data are available from the DGGS website: http://doi.org/10.14509/31045. Purpose: The goal of this standard routine, and in comparing multi-year secondary standard results, is to ensure that data for unknown sample analyses is precise and comparable. This standard will enable us to correlate tephra units from Alaskan volcanos to better understand and detect changes in composition at a volcano over time. Supplemental_Information: >Calibrants: Name of calibration standard, matches values in Conditions table for each analyte, microprobe lab for the calibrant values, where the calibration standard was obtained, type of material, and elemental concentrations >Conditions: Electron microprobe beam conditions, calibration standards, spectrometer assignment, diffraction crystal assignments, analysis order, counting times, and time-dependent intensity correction flag (Y/N) for each element >RepeatUnkns: Microprobe session identifier to link analyses to a set of analytical conditions (usually used on multiple consecutive days) >SecondaryStandardResults: Categorical identification of secondary standards, secondary standard name used in analysis runs, date and time of analysis, and element weight percents >SecondaryStandardValues: Name of secondary standard used in analysis categorization, Y/N flag to indicate whether the standard is part of the traveling AVO standard mount, element reference values, and literature citations for standard reference values Time_Period_of_Content: Time_Period_Information: Multiple_Dates/Times: Single_Date/Time: Calendar_Date: 2018 Single_Date/Time: Calendar_Date: 2023 Currentness_Reference: ground condition Status: Progress: Complete Maintenance_and_Update_Frequency: None planned Spatial_Domain: Bounding_Coordinates: West_Bounding_Coordinate: -178.817961 East_Bounding_Coordinate: -104.060291 North_Bounding_Coordinate: 71.277684 South_Bounding_Coordinate: 43.359849 Keywords: Theme: Theme_Keyword_Thesaurus: ISO 19115 Topic Category Theme_Keyword: geoscientificInformation Theme: Theme_Keyword_Thesaurus: Alaska Division of Geological & Geophysical Surveys Theme_Keyword: Active Volcanoes Theme_Keyword: Analyses and Sampling Theme_Keyword: Analytical Lab Results Theme_Keyword: Analytical Results Theme_Keyword: Chemistry Theme_Keyword: Correlation Theme_Keyword: DGGS Theme_Keyword: Geochemical Data Theme_Keyword: Geochemistry Theme_Keyword: Geologic Theme_Keyword: Geologic Hazards Theme_Keyword: Geological Process Theme_Keyword: Geology Theme_Keyword: Glass Theme_Keyword: Igneous Theme_Keyword: Lab Methods Theme_Keyword: Pyroclastics Theme_Keyword: Tephra Theme_Keyword: Volcanic Theme_Keyword: Volcanic Ash Theme_Keyword: Volcanic Eruption Theme_Keyword: Volcaniclastics Theme_Keyword: Volcanoes Theme_Keyword: Volcanology Place: Place_Keyword_Thesaurus: Alaska Division of Geological & Geophysical Surveys Place_Keyword: Alaska Place_Keyword: Alaska, State of Place_Keyword: Cook Inlet Temporal: Temporal_Keyword_Thesaurus: 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 Temporal_Keyword: Holocene 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. Point_of_Contact: Contact_Information: Contact_Organization_Primary: Contact_Organization: Alaska Division of Geological & Geophysical Surveys Contact_Position: Metadata Manager 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_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 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. Data_Set_Credit: This article has been peer-reviewed and approved for publication consistent with USGS Fundamental Science Practices (pubs.usgs.gov/circ/1367). We appreciate reviews provided by Heather Lowers and Steve Kuehn, metadata review by Simone Montayne, and editorial handling by Kristen Janssen. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Cross_Reference: Citation_Information: Originator: Cameron, C.E. Originator: Crass, S.W. Originator: AVO Staff Publication_Date: 2022 Title: Geologic Database of Information on Volcanoes in Alaska (GeoDIVA) Series_Information: Series_Name: Digital Data Series Issue_Identification: DDS 20 Publication_Information: Publication_Place: Fairbanks, Alaska, United States Publisher: Alaska Division of Geological & Geophysical Surveys Online_Linkage: https://doi.org/10.14509/30901 Cross_Reference: Citation_Information: Originator: Mulliken, K.M. Originator: Schaefer, J.R. Originator: Cameron, C.E. Publication_Date: 2018 Title: Geospatial distribution of tephra fall in Alaska: a geodatabase compilation of published tephra fall occurrences from the Pleistocene to the present Series_Information: Series_Name: Miscellaneous Publication Issue_Identification: MP 164 Publication_Information: Publication_Place: Fairbanks, Alaska, United States Publisher: Alaska Division of Geological & Geophysical Surveys Other_Citation_Details: 46 p Online_Linkage: https://doi.org/10.14509/29847 Cross_Reference: Citation_Information: Originator: Wallace, K.L. Originator: Cameron, C.E. Originator: Waythomas, C.F. Originator: Perreault, J.M. Publication_Date: 2020 Title: Major-oxide and trace-element geochemical data from the tephra collected on Veniaminof volcano, Alaska Series_Information: Series_Name: Raw Data File Issue_Identification: RDF 2020-17 Publication_Information: Publication_Place: Fairbanks, Alaska, United States Publisher: Alaska Division of Geological & Geophysical Surveys Other_Citation_Details: 5 p Online_Linkage: https://doi.org/10.14509/30578 Cross_Reference: Citation_Information: Originator: Wallace, K.L. Originator: Hayden, L.A. Originator: Neal, C.A. Publication_Date: 2017 Title: Major-element glass compositions of tephra from the circa 3.6 ka eruption of Aniakchak volcano, Alaska Peninsula, Alaska Series_Information: Series_Name: Raw Data File Issue_Identification: RDF 2017-9 Publication_Information: Publication_Place: Fairbanks, Alaska, United States Publisher: Alaska Division of Geological & Geophysical Surveys Other_Citation_Details: 9 p Online_Linkage: https://doi.org/10.14509/29777 Cross_Reference: Citation_Information: Originator: Worden, A.K. Originator: Schaefer, J.R. Originator: Mulliken, K.M. Publication_Date: 2018 Title: Tephra occurrence in Alaska: a map-based compilation of stratigraphic tephra data Series_Information: Series_Name: Miscellaneous Publication Issue_Identification: MP 165 Publication_Information: Publication_Place: Fairbanks, Alaska, United States Publisher: Alaska Division of Geological & Geophysical Surveys Other_Citation_Details: 19 p Online_Linkage: https://doi.org/10.14509/30059 Data_Quality_Information: Attribute_Accuracy: Attribute_Accuracy_Report: This data release covers analyses made between 2018 and 2023, during which an effort was made to standardize the analytical setup, although slight variations in calibration and processing did occur. Multiple secondary standard basalts and rhyolite glasses were run throughout all analytical sessions, and individual secondary standard point analyses are provided in the data file. The accompanying report and data files provide additional detail and are intended to streamline reporting by providing a detailed explanation of the methodology and to ensure that data for unknown sample analyses is precise and comparable. Logical_Consistency_Report: Not applicable Completeness_Report: This data releaase is complete. Positional_Accuracy: Horizontal_Positional_Accuracy: Horizontal_Positional_Accuracy_Report: Samples were collected from the Cook Inlet area and sampling locations are available via the Geological Database of Information on Volcanoes in Alaska (GeoDIVA; Cameron and others, 2022). Lineage: Process_Step: Process_Description: Analytical setup - We prepared a traveling mount of secondary standards that can be used on multiple instruments in different laboratories because microbeam standards or reference materials often suffer heterogeneities at small scales and between individual aliquots (chips of materials or single crystals; Jarosewich and others, 1980). Thus, we can ensure our standard analyses are directly comparable and independently verify compositions of internal lab standards. This mount includes five natural volcanic glasses: two low-silica glasses (VG-2, A-99) and three high-silica glasses (VG-568, RLS-132, KN-18). Three of these standards (VG-2, A-99, VG-568) were provided by the Smithsonian Museum of Natural History and are readily available to the analytical community. We mounted unknown tephra samples with epoxy in 25-mm-diameter rounds (hereafter called round mounts) or on commercially produced polished petrographic sections. We progressively polished round mounts with diamond grit to 1 µm and a final polish with 0.05 µm colloidal silica or 0.1 µm alumina suspension. Petrographic section preparation followed vendor protocols but typically included a final polish of 0.1 µm or finer. Our traveling standard mount was in a 25 mm-diameter round mount. Samples and calibration standards were all carbon-coated to ~22 nm thickness (indigo-blue interference on brass monitors). Analyses were performed at the UAF Advanced Instrumentation Laboratory and the USGS Electron Microprobe in Menlo Park, California. UAF analyses reported here used a JEOL JXA 8530F electron microprobe. Tephra matrix analyses were performed at 15 kV, 10 nA, and a 5 µm defocused beam. Identical beam conditions were used on the Menlo Park JEOL JXA 8530F+ electron microprobe. Calibration standards, spectrometer assignments, peak and background count times, and time-dependent intensity corrections are summarized for each analyte in Conditions and Calibrants data tables, and attempts were made to keep these values constant over all sessions. However, some variations occurred and are noted. All elements were measured on K alpha lines with linear background corrections. Data were collected and processed with Probe for EPMA software (Probe Software 2023). In UAF analyses, Na, K, and Al were measured first and corrected with a time-dependent intensity correction (TDI; Nielsen and Sigurdsson, 1981). Menlo Park analyses did not implement a TDI correction for the analyses reported here. All cations were obtained from raw intensities using the Phi-Rho-Z intensity corrections (Armstrong, 1988), while oxygen was calculated by cation stoichiometry; however, oxygen equivalent for halogens (Cl) was not used. Additional detail, results, and complete reference list can be found in the accompanying report and data tables. Process_Date: 2022 Process_Step: Process_Description: Analytical methods - Multiple secondary standard basalts and rhyolite glasses were run throughout all analytical sessions, and individual secondary standard point analyses are provided in the SecondaryStandardResults data file. We consider precision after normalization to 100 percent anhydrous (but including Cl), with Fe concentrations calculated as the total Fe (denoted by FeOT) and compared to normalized accepted values (SecondaryStandardValues data table) to determine accuracy. Normalization corrects many anomalously low or high totals (above or below a 100 percent total), which, through our examination, appear to affect all elements proportionally. Normalization is often necessary for analyzing unknown tephra that may be affected by secondary hydration resulting in low totals, or where analysis of thin glass on bubble walls results in low totals. Although this is less of an issue for the secondary standards presented here, we prefer to treat our secondary standards similarly to our unknowns to provide the most accurate representation of unknown analysis accuracy and precision. Our traveling secondary standard mount was incorporated into analyses as an unknown block one or more times per analytical session. It included Smithsonian standard glasses VG-2 (NMNH 111240-52), A-99 (NMNH 113498-1), VG-568 (NMNH 72854), USGS standard RLS-132, and KN-18. Four of the measured standards were part of the UAF EPMA internal standard block and had unique names BG-1 (VG-2_UAF), BG-2 (A-99_UAF), BG-3 (NMNH 113716-1), Rhyolite (VG-568_UAF), and CCNM (also known as Lipari UA5831). An internal aliquot of VG-2 was also analyzed on the USGS Menlo Park microprobe (VG-2_cal) along with an internal rhyolite (RLS-75). Accepted values for Smithsonian glasses are from Jarosewich and others (1980), except for Mg on VG-2 from Helz and others (2014), and Cl concentrations from various sources compiled on the Smithsonian NMNH website5 RLS-132 values are reported in Macdonald and others (1992). All our accepted values and their referenced sources are provided in the SecondaryStandardValues data table. Process_Date: 2022 Spatial_Data_Organization_Information: Direct_Spatial_Reference_Method: point Spatial_Reference_Information: Horizontal_Coordinate_System_Definition: Geographic: Latitude_Resolution: 0.000001 Longitude_Resolution: 0.000001 Geographic_Coordinate_Units: decimal degrees Geodetic_Model: Horizontal_Datum_Name: NAD83 Ellipsoid_Name: GRS 80 Semi-major_Axis: 6378137 Denominator_of_Flattening_Ratio: 298.257222101 Entity_and_Attribute_Information: Detailed_Description: Entity_Type: Entity_Type_Label: Calibrants.csv, Calibrants-data-dictionary.csv Entity_Type_Definition: Name of calibration standard, matches values in Conditions table for each analyte, microprobe lab for the calibrant values, where the calibration standard was obtained, type of material, and elemental concentrations Entity_Type_Definition_Source: AVO, this report Entity_Attribute_Layer_Name: Calibrants Detailed_Description: Entity_Type: Entity_Type_Label: Conditions.csv, Conditions-data-dictionary.csv Entity_Type_Definition: Electron microprobe beam conditions, calibration standards, spectrometer assignment, diffraction crystal assignments, analysis order, counting times, and time-dependent intensity correction flag (Y/N) for each element Entity_Type_Definition_Source: AVO, this report Entity_Attribute_Layer_Name: Conditions Detailed_Description: Entity_Type: Entity_Type_Label: RepeatUnkns.csv, RepeatUnkns-data-dictionary.csv Entity_Type_Definition: Microprobe session identifier to link analyses to a set of analytical conditions (usually used on multiple consecutive days) Entity_Type_Definition_Source: AVO, this report Entity_Attribute_Layer_Name: RepeatUnkns Detailed_Description: Entity_Type: Entity_Type_Label: SecondaryStandardResults.csv, SecondaryStandardResults-data-dictionary.csv Entity_Type_Definition: Categorical identification of secondary standards, secondary standard name used in analysis runs, date and time of analysis, and element weight percents Entity_Type_Definition_Source: AVO, this report Entity_Attribute_Layer_Name: SecondaryStandardResults Detailed_Description: Entity_Type: Entity_Type_Label: SecondaryStandardValues.csv, SecondaryStandardValues-data-dictionary.csv Entity_Type_Definition: Name of secondary standard used in analysis categorization, Y/N flag to indicate whether the standard is part of the traveling AVO standard mount, element reference values, and literature citations for standard reference values Entity_Type_Definition_Source: AVO, this report Entity_Attribute_Layer_Name: SecondaryStandardValues Distribution_Information: Distributor: Contact_Information: Contact_Organization_Primary: Contact_Organization: Alaska Division of Geological & Geophysical Surveys Contact_Position: Metadata Manager 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_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 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. Resource_Description: MP 174 Distribution_Liability: 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. 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