Identification_Information: Citation: Citation_Information: Originator: Larsen, J.F. Originator: Schaefer, J.R. Originator: Dietterich, H.R. Originator: Vallance, J.W. Originator: Rosenkrans, H.S. Originator: Van Eaton, Alexa Originator: Wallace, K.L. Originator: Kleiner, Wil Originator: Hatfield, Virginia Publication_Date: 2026 Title: Stratigraphic and electron microprobe data for Holocene tephra from Makushin Volcano, Alaska, and for interbedded tephra from other volcanoes located among or near the islands of the eastern Aleutians Geospatial_Data_Presentation_Form: spreadsheet Series_Information: Series_Name: Raw Data File Issue_Identification: RDF 2026-12 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/10.14509/32059 Description: Abstract: Stratigraphic and electron microprobe data for Holocene tephra from Makushin Volcano, Alaska, and for interbedded tephra from other volcanoes located among or near the islands of the eastern Aleutians, Raw Data File 2026-12, summarizes tephrostratigraphy and electron probe microanalytical (EPMA) data from Makushin Volcano and regional tephras in the Unalaska Island area. The data were collected by scientists from the Alaska Volcano Observatory (AVO) and the Cascades Volcano Observatory during fieldwork from 2011 to 2024. Additional EPMA analyses from this time interval are reported in Larsen and others (2020). Makushin Volcano is part of the Makushin Volcanic Field (McConnell and others, 1998) in the north central part of Unalaska Island, Alaska, approximately 1,290 km southwest of Anchorage and 20 km west of the City of Unalaska and the Port of Dutch Harbor. Makushin erupted explosively to produce two large-volume, explosive Holocene deposits with ages of 9,040 (Makushin Valley) and 7,900 (Driftwood) cal. yr B.P. Since then, Makushin Volcano has erupted numerous times, though individual eruptions have been significantly less voluminous than those of the early Holocene events. The most recent eruption in 1995 produced small ash plumes but left no clearly preserved deposits. Eruptions from volcanoes on neighboring islands also deposited significant tephra fall on Unalaska Island. Tephra from the Okmok II caldera-forming eruption about 2050 years ago is 1-2 cm thick and drapes the area near Dutch Harbor and the City of Unalaska. Tephra from two large explosive eruptions of the Akutan volcano also covered the area 1,600 and 8,700 years ago. Tephra from the older Akutan eruption is up to 40 cm thick in the City of Unalaska. An additional, older silicic tephra sample originated from a distant volcano, but its provenance remains undetermined. Data in this report are included in the public Geologic Database of Information on Volcanoes in Alaska (GeoDIVA; Cameron and others, 2022, http://doi.org/10.14509/geodiva). These data and accompanying discussion are released as a DGGS Raw Data File, and all publication components are available from the DGGS website at: http://doi.org/10.14509/32059. Purpose: This dataset contains LA-ICP-MS U-Pb zircon ages and trace and rare-earth element data from 14 igneous and metaigneous samples collected for the USGS Earth MRI Steese and Chena mapping projects. These data support efforts to modernize geologic mapping in regions with critical mineral potential across the Yukon-Tanana Upland. The purpose of the dataset is to constrain the timing of igneous activity to inform geologic mapping, tectonic interpretations, and mineralization studies in east-central Alaska. Supplemental_Information: >Makushin-Stations: Stratigraphic section and sample station ID numbers, coordinates, and location descriptions. >Makushin-Samples: Sample ID numbers with station ID, source volcano, sample type, and description. >Makushin-Layers: Stratigraphic section layer data from each project year. >Makushin-EPMA: Single-point EPMA analyses including sample ID, session date, MethodID, analytical group, point number, and glass populations. >Makushin-Analytical-Conditions: Analytical conditions, MethodID, calibration standards, detector, crystal, and count times. >Makushin-Standards: Working standard data in single analytical point format. Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 2025 Currentness_Reference: ground condition Status: Progress: Complete Maintenance_and_Update_Frequency: None planned Spatial_Domain: Bounding_Coordinates: West_Bounding_Coordinate: -167.052549 East_Bounding_Coordinate: -165.810670 North_Bounding_Coordinate: 54.166020 South_Bounding_Coordinate: 53.498643 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: Aleutian Arc Theme_Keyword: Analyses Theme_Keyword: Analyses and Sampling Theme_Keyword: Analytical Lab Results Theme_Keyword: Analytical Results Theme_Keyword: Andesite Theme_Keyword: Ash Cloud Theme_Keyword: Ashfall Theme_Keyword: Caldera Theme_Keyword: Chemistry Theme_Keyword: Colluvium Theme_Keyword: Correlation Theme_Keyword: Crystals Theme_Keyword: DGGS Theme_Keyword: Diopside Theme_Keyword: Disseminated Theme_Keyword: Drift Theme_Keyword: Emergency Preparedness Theme_Keyword: Geochemical Analysis Theme_Keyword: Geochemical Data Theme_Keyword: Geochemistry Theme_Keyword: Geologic Theme_Keyword: Geologic Hazards Theme_Keyword: Glass Theme_Keyword: Ignimbrite Theme_Keyword: Instrumentation Theme_Keyword: Lahar Theme_Keyword: Methods Theme_Keyword: Microprobe Analysis Theme_Keyword: Petrology Theme_Keyword: Plagioclase Theme_Keyword: Provenance Theme_Keyword: Pumice Theme_Keyword: Scoria Theme_Keyword: Stratigraphy Theme_Keyword: Surface Theme_Keyword: Tephra Theme_Keyword: Tephrostratigraphy Theme_Keyword: Terrace Theme_Keyword: Till Theme_Keyword: Tuff Theme_Keyword: Volcanic Theme_Keyword: Volcanic Arc Theme_Keyword: Volcanic Ash Theme_Keyword: Volcanic Deposits Theme_Keyword: Volcaniclastic Theme_Keyword: Volcaniclastic Deposits Theme_Keyword: Volcaniclastic Rocks Theme_Keyword: Volcaniclastics Theme_Keyword: Volcanoes Theme_Keyword: Volcanology Place: Place_Keyword_Thesaurus: Alaska Division of Geological & Geophysical Surveys Place_Keyword: Aatqaayang Place_Keyword: Achuugix Tanaxtaqax Place_Keyword: Agaan Qagangaa Place_Keyword: Agamgik Bay Place_Keyword: Agamgim Yaga Place_Keyword: Agiisax Place_Keyword: Agnes Beach Place_Keyword: Akutan Place_Keyword: Akutan Bay Place_Keyword: Akutan Harbor Place_Keyword: Akutan Island Place_Keyword: Akutan Peak Place_Keyword: Amaknak Island Place_Keyword: Amugam-Tangingin Place_Keyword: Amugul Bay Place_Keyword: Amugul Creek Place_Keyword: Anigaaxsix Place_Keyword: Arkansas Beach Place_Keyword: Ayagaa Tunutux Place_Keyword: Baby Pass Place_Keyword: Bailey Ledge Place_Keyword: Beaver Inlet Place_Keyword: Bering Sea Place_Keyword: Biorka Place_Keyword: Bishop Point Place_Keyword: Blueberry Bay Place_Keyword: Broad Bay Place_Keyword: Bunker Hill Place_Keyword: Cape Cheerful Place_Keyword: Cape Morgan Place_Keyword: Cape Sedanka Place_Keyword: Cape Starichkof Place_Keyword: Cape Wislow Place_Keyword: Cape Yanaliuk Place_Keyword: Captains Bay Place_Keyword: Cascade Bight Place_Keyword: Chaliuknak Place_Keyword: Chaluuknam Yaga Place_Keyword: Chaluuknax Place_Keyword: Chamax Place_Keyword: Chixchan-Qala Place_Keyword: Chugaagix-Udax Place_Keyword: Constantine Bay Place_Keyword: Deep Bay Place_Keyword: Devilfish Point Place_Keyword: Driftwood Bay Place_Keyword: Dutch Harbor Place_Keyword: East Channel Place_Keyword: Eider Point Place_Keyword: English Bay Place_Keyword: Erskine Bay Place_Keyword: Erskine Point Place_Keyword: Expedition Island Place_Keyword: Fishermans Point Place_Keyword: Flat Top Peak Place_Keyword: Fox Islands Place_Keyword: Hog Island Place_Keyword: Hot Springs Bay Place_Keyword: Iikux Place_Keyword: Iliuliuk Bay Place_Keyword: Iliuliuk Harbor Place_Keyword: Iliuliuk Reef Place_Keyword: Kalekta Bay Place_Keyword: Kiichxix Kangaxtax Place_Keyword: Kof Point Place_Keyword: Koriga Point Place_Keyword: Lava Bight Place_Keyword: Lava Point Place_Keyword: Lofty Mountain Place_Keyword: Makushin Place_Keyword: Makushin Bay Place_Keyword: Makushin Valley Place_Keyword: Makushin Valley River Place_Keyword: Makushin Volcano Place_Keyword: Malga Bay Place_Keyword: Margaret Bay Place_Keyword: Morris Cove Place_Keyword: Mount Ballyhoo Place_Keyword: Mount Coxcomb Place_Keyword: Mount Marshall Reese Place_Keyword: Mount Newhall Place_Keyword: Nateekin Bay Place_Keyword: Nateekin River Place_Keyword: Obernoi Point Place_Keyword: Pacific Ocean Place_Keyword: Passage Point Place_Keyword: Point Kadin Place_Keyword: Point Tebenkof Place_Keyword: Port Levashef Place_Keyword: Portage Bay Place_Keyword: Pyramid Peak Place_Keyword: Qawa-Chunguxtan Place_Keyword: Qigaan-Kadaa Place_Keyword: Ququgan Place_Keyword: Qusiixtax Place_Keyword: Red Cinder Dome Place_Keyword: Reef Bight Place_Keyword: Reef Point Place_Keyword: Reese Bay Place_Keyword: Ridge Point Place_Keyword: Round Island Place_Keyword: Sandy Cove Place_Keyword: Saxtusix Place_Keyword: Shaishnikof River Place_Keyword: Sisek Cove Place_Keyword: Split Top Mountain Place_Keyword: Strait Bay Place_Keyword: Summer Bay Place_Keyword: Summer Bay Lake Place_Keyword: Swallow Reef Place_Keyword: Table Top Mountain Place_Keyword: Tanaskan Bay Place_Keyword: Tanasxan Tangingin Place_Keyword: Tanaxsiqax Place_Keyword: Tarasof Point Place_Keyword: Three Island Bay Place_Keyword: Udagak Bay Place_Keyword: Udagak Strait Place_Keyword: Ugadachan Creek Place_Keyword: Ugadaga Bay Place_Keyword: Ulalux Place_Keyword: Unalaska Place_Keyword: Unalaska Bay Place_Keyword: Unalaska Lake Place_Keyword: Unalga Island Place_Keyword: Usmichix Place_Keyword: Usof Bay Place_Keyword: Vulcan Point Place_Keyword: Whalebone Cape Place_Keyword: Wide Bay Place_Keyword: Wislow Island Place_Keyword: Xatacyan Lagoon 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: Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Matt Loewen provided ample assistance with the stratigraphic section data sheets. Michelle Coombs assisted with correlating Nateekin electron microprobe data with the Akutan source eruption. We thank the U.S. Fish and Wildlife Service and the Ounalashka Corporation for permission to conduct this fieldwork on their lands and for their generous assistance with many aspects of our fieldwork and engagement with the Unalaska community. Maritime Helicopters and Pathfinder Aviation supported this work, and we thank their pilots for safe and successful field seasons. 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: Larsen, J.F. Originator: Neal, C.A. Originator: Schaefer, J.R. Originator: Nye, C.J. Publication_Date: 2023 Title: Geologic map of Okmok Volcano Series_Information: Series_Name: Report of Investigation Issue_Identification: RI 2023-1 Publication_Information: Publication_Place: Fairbanks, Alaska, United States Publisher: Alaska Division of Geological & Geophysical Surveys Other_Citation_Details: 63 p., 4 sheets Online_Linkage: https://doi.org/10.14509/31015 Cross_Reference: 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 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 Cross_Reference: Citation_Information: Originator: McConnell, V.S. Originator: Beget, J.E. Originator: Roach, A.L. Originator: Bean, K.W. Originator: Nye, C.J. Publication_Date: 1998 Title: Geologic map of the Makushin volcanic field, Unalaska Island, Alaska Series_Information: Series_Name: Report of Investigation Issue_Identification: RI 97-20 Publication_Information: Publication_Place: Fairbanks, Alaska, United States Publisher: Alaska Division of Geological & Geophysical Surveys Other_Citation_Details: 2 sheets, scale 1:63,360 Online_Linkage: https://doi.org/10.14509/2576 Data_Quality_Information: Attribute_Accuracy: Attribute_Accuracy_Report: 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. Logical_Consistency_Report: Not applicable Completeness_Report: This data release is complete. Positional_Accuracy: Horizontal_Positional_Accuracy: Horizontal_Positional_Accuracy_Report: Location data were collected with handheld GPS devices and recorded in field notebooks. Lineage: Process_Step: Process_Description: Field data collection - AVO geologists collected samples and recorded observations from 109 stratigraphic sections during fieldwork conducted between 2011 and 2024. Stratigraphic sections were described and recorded in field notebooks during the 2011-2018 seasons. During 2023 and 2024, the sections were described both in field notebooks and digitally using the StraboSpot iPad software (strabospot.org). Location data were collected with handheld GPS devices and recorded in field notebooks. Station locations are provided using the NAD83 datum. Process_Date: 2024 Process_Step: Process_Description: Sample analysis - This report presents EPMA data from 126 tephra samples. The samples were collected in the field and processed at the U.S. Geological Survey Alaska Tephra Laboratory (USGS ATL) in Anchorage. Bulk samples were sonicated in tap water for 10 to 30 minutes, wet sieved into greater than 250 micrometer, 125 to 250 micrometer, and 63 to 125 micrometer fractions, and material finer than 63 micrometer was discarded. The sieved fractions were dried at 40 degrees Celsius for 12 to 24 hours and examined under a binocular microscope to identify the size fraction with the highest glass content. For most samples, the modal fraction was selected for analysis and used to prepare grain mounts. Polished grain mounts were produced on one inch epoxy pucks and glass slides at USGS ATL and the University of Alaska Fairbanks (UAF), following Loewen et al. (2023). Analyses were performed on the UAF JEOL JXA 8530F electron microprobe using the AVO tephra routine. Operating conditions were 15 kiloelectron volts, 5 to 10 nanoamperes, and a 5 micrometer beam to reduce alkali migration. Sodium was measured first, and time dependent intensity corrections were applied using Probe for EPMA software. Calibration standards included common mineral and glass reference materials; details for each analytical session are provided in a separate table. Working standards, analyzed throughout each session, included rhyolitic glass, CCNM, and basaltic glasses BG 2 and BG 3. Analytical uncertainties are discussed in Loewen et al. (2023). Additional details on laboratory methods and data reduction are provided in the accompanying report. Process_Date: 2025 Spatial_Data_Organization_Information: Direct_Spatial_Reference_Method: point Spatial_Reference_Information: Horizontal_Coordinate_System_Definition: Geographic: Latitude_Resolution: 0.0000001 Longitude_Resolution: 0.0000001 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: rdf2026-12-Makushin-Stations.xlsx, rdf2026-12-Makushin-Stations-Data-Dictionary.xlsx Entity_Type_Definition: Stratigraphic section and sample station ID numbers, coordinates, and location descriptions. Entity_Type_Definition_Source: AVO Entity_Attribute_Layer_Name: Makushin-Stations Detailed_Description: Entity_Type: Entity_Type_Label: rdf2026-12-Makushin-Samples.xlsx, rdf2026-12-Makushin-Samples-Data-Dictionary.xlsx Entity_Type_Definition: Sample ID numbers with station ID, source volcano, sample type, and description. Entity_Type_Definition_Source: AVO Entity_Attribute_Layer_Name: Makushin-Samples Detailed_Description: Entity_Type: Entity_Type_Label: rdf2026-12-Makushin-Layers.xlsx, rdf2026-12-Makushin-Layers-Data-Dictionary.xlsx Entity_Type_Definition: Stratigraphic section layer data from each project year. Entity_Type_Definition_Source: AVO Entity_Attribute_Layer_Name: Makushin-Layers Detailed_Description: Entity_Type: Entity_Type_Label: rdf2026-12-Makushin-EPMA.xlsx, rdf2026-12-Makushin-EPMA-Data-Dictionary.xlsx Entity_Type_Definition: Single-point EPMA analyses including sample ID, session date, MethodID, analytical group, point number, and glass populations. Entity_Type_Definition_Source: AVO Entity_Attribute_Layer_Name: Makushin-EPMA Detailed_Description: Entity_Type: Entity_Type_Label: rdf2026-12-Makushin-Analytical-Conditions.xlsx, rdf2026-12-Makushin-Analytical-Conditions-Data-Dictionary.xlsx Entity_Type_Definition: Analytical conditions, MethodID, calibration standards, detector, crystal, and count times. Entity_Type_Definition_Source: AVO Entity_Attribute_Layer_Name: Makushin-Analytical-Conditions Detailed_Description: Entity_Type: Entity_Type_Label: rdf2026-12-Makushin-EPMA-Standards.xlsx, rdf2026-12-Makushin-EPMA-Standards-Data-Dictionary.xlsx Entity_Type_Definition: Working standard data in single analytical point format. Entity_Type_Definition_Source: AVO Entity_Attribute_Layer_Name: Makushin-Standards 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: RDF 2026-12 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. Standard_Order_Process: Non-digital_Form: 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. 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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. Metadata_Extensions: Online_Linkage: https://dggs.alaska.gov/metadata/dggs.ext Profile_Name: dggs metadata extensions