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Major-oxide and trace-element geochemical data from the tephra collected on Veniaminof volcano, Alaska
Alaska Volcano Observatory (AVO) geologists from the U.S. Geological Survey (USGS) and the Alaska Division of Geological & Geophysical Surveys (DGGS) conducted fieldwork at Mount Veniaminof during field excursions between 2001 and 2016. The primary purpose of the fieldwork was geologic investigation of Veniaminof volcano to elucidate its eruptive history and understand its eruptive behavior. Teams of geologists focused on 1) edifice lava flows, 2) flowage deposits (lahars and pyroclastic flows), and 3) tephra-fall deposits. This Raw Data File comprises 61 whole-rock analyses of pumices from Holocene-age tephra deposits collected from 36 field stations on the flanks of Veniaminof volcano in 2001-2004, 2010, and 2016. All but four samples in this report were collected by geologists Kristi Wallace and Chris Waythomas during 1- to 2-week summer fieldwork campaigns. Thomas Miller and Charles Bacon contributed four pumice samples of a young dacite-composition tephra collected in 2001 and 2002. Mount Veniaminof is an ice-clad, basalt-to-dacite stratovolcano topped by an ice-filled caldera 10 km (about 6 mi) in diameter, located 775 km (482 mi) southwest of Anchorage on the Alaska Peninsula. With a volume of approximately 350 km3 (approximately 84 mi3) Veniaminof is one of the largest and most active volcanoes of the Aleutian Arc. Two Holocene caldera-forming eruptions are recorded in extensive pyroclastic-flow deposits around the volcano. Veniaminof has had at least 15 eruptions in the past 200 years, all from the approximately 300-m-high (about 984-ft-high) intracaldera cone and all largely basaltic-basaltic andesite composition, producing small lava flows and minor tephra deposits mostly confined to the caldera boundaries. The most recent explosive eruption was in 2018. Geochemical characterization of tephra deposits is most commonly executed by using glass-phase chemistry rather than whole-rock (bulk) geochemistry. The bulk composition of a tephra may change over fallout distance by eolian fractionation and therefore cannot be used to correlate tephra deposits over long distances. Whole-rock composition is commonly used to characterize juvenile material from flowage deposits (lahars and pyroclastic flows) and lavas. In order to readily compare (correlate) juvenile material from proximal tephra-fall deposits with other proximal deposits, tephra whole-rock analysis is required. This Raw Data File is focused only on whole-rock geochemical analyses of significant coarse-grained tephra deposits exposed on the flanks of Veniaminof volcano for use in correlating tephra deposits across the large volcanic edifice, and with proximal flowage deposits and edifice lava flows. Results of glass geochemistry of Veniaminof tephra and all other whole-rock analyses of samples collected is part of an ongoing study and not included in this report. Files can also be downloaded from the DGGS website (http://doi.org/10.14509/30578) and is also available in .html and .csv from the AVO Geochemical Database (https://avo.alaska.edu/geochem). Sample descriptions, locations, and sample types are included in the analytical data table. Samples collected during this project, including hand sample material, remaining powder from these whole-rock analyses, and partially crushed sample remains are stored at the Alaska Geologic Materials Center or at the USGS Alaska Tephra Laboratory in Anchorage.
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Major-oxide and trace-element geochemical data from rocks collected in 2010 in the Tyonek Quadrangle, Alaska
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Cook Inlet has been recognized as the second-largest petroleum province in Alaska, second only to the North Slope. The south-central Tyonek Quadrangle is an area of significant geologic interest because it is the only location in Cook Inlet where the entire producing stratigraphy of the basin is exposed on the surface. Additionally, this area encompasses the structural boundary between the forearc basin and its sediment source rocks. To better understand the petroleum system and the geologic relationships between the exhumed arc intrusive rocks and adjacent Cenozoic stratigraphy of the Cook Inlet forearc basin, during the summer of 2010 the Alaska Division of Geological & Geophysical Surveys conducted a federally-funded geologic field mapping project. As a part of this project DGGS collected 44 rock samples for geochemical analyses from Late Cretaceous and Paleogene intrusive and volcanic lithologies that compose part of the Alaska-Aleutian Range batholith and arc. Major-oxide, minor-oxide, and trace-element geochemical data presented here provide new information about the genesis and potential mineralization of igneous rocks in the western Neacola and southern Tordrillo mountains. The analytical data tables associated with this report are available in digital format as comma-separated value (CSV) files.
Major-oxide and trace-element geochemical data from rocks collected in 2015 in lower Cook Inlet, Iniskin - Tuxedni region, Alaska
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The Iniskin-Tuxedni Bay area contains excellent exposures of nearly all of the lower Cook Inlet Mesozoic succession, including most of the stratigraphic sections that define the interval and the petroleum source rocks that comprise the basin. An underdeveloped understanding of the Mesozoic petroleum system has led the Alaska Department of Natural Resources' Division of Geological & Geophysical Surveys and Division of Oil and Gas, and the U.S. Geological Survey to collaborate on a multi-year project that includes two major mapping campaigns. Geologic mapping between Chinitna Bay and the Johnson River during the 2015 field season encompassed volcanic arc rocks northwest of the Bruin Bay fault system, and Mesozoic forearc basin stratigraphy extending to the Cook Inlet coast. To understand and represent the complexity of the volcanic arc systems in the region, we analyzed ten samples of volcanic rocks, two samples of gabbro sill, and one mafic dike sample for major and minor oxides and trace elements. Although mineralization was not noted in the samples collected for major oxide analysis, findings of interest include: one sample with weak Cr and Ni enrichment, three samples with lightly elevated As, and slight S anomalies (0.37 wt percent and 0.25 wt percent) in samples described as Talkeetna Formation. The Talkeetna Formation sample with 0.37 wt percent S also had elevated Cu (321 ppm) and As (58 ppm). The analytical data tables associated with this report are available in digital format as comma-separated values (CSV) file.
Tephra samples and analyses from the 2018-2023 eruption of Semisopochnoi Volcano, Alaska
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Tephra samples and analyses from the 2018-2023 eruption of Semisopochnoi Volcano, Alaska, Raw Data File 2025-15, includes samples and analyses collected from the 2018-2023 eruption of Semisopochnoi volcano in the western Aleutian Islands, Alaska. Samples were collected during two field visits: May 30 to June 1, 2021, and June 10, 2023. A total of sixteen samples were collected across Semisopochnoi Island at varying distances from the eruption source, the north crater of Mount Young. Samples were collected from the surface on snow, grass, or other substrates that suggested deposition during recent eruptive activity but are, in all cases, aggregates of prior eruption events up to the sample date and may contain minor wind-blown contamination from older surfaces. These data and report are available from the DGGS website: http://doi.org/10.14509/31645 and a subset of the results are archived in the Geologic Database of Information on Volcanoes in Alaska (GeoDIVA; Cameron and others, 2022, doi.org/10.14509/geodiva).
Major oxide and trace element analyses for rock samples from the Haines-Takshanuk Mountains-Chilkat Peninsula area STATEMAP project, southeast Alaska
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Major oxide and trace element analyses for rock samples from the Haines-Takshanuk Mountains-Chilkat Peninsula area STATEMAP project, southeast Alaska, Raw Data File 2024-18, presents whole-rock and major- and trace-element geochemistry of rock samples collected to support geologic mapping in portions of the Skagway A-1, A-2, B-1, B-2, and B-3 15-minute quadrangles, an area of approximately 300 square miles. On December 2, 2020, a landslide triggered by an atmospheric river weather phenomenon at Beach Road in Haines, Alaska, claimed two lives. Numerous debris flows were also recorded around town during the same rain event, especially along Lutak Spur Road. As a response, the Haines-Takshanuk Mountains-Chilkat Peninsula area STATEMAP project's goal is to create an updated 1:50,000-scale geologic map in paper and digital GIS formats. A comprehensive, detailed map constructed using modern analytical methods is critical to help land managers and residents make informed decisions when planning future development and evaluating risks to infrastructure. During July 2022, May 2023, and August 2023, geologists from the Alaska Division of Geological & Geophysical Surveys (DGGS) conducted fieldwork supporting surficial and bedrock mapping (Truskowski and others, 2024). This data file is released as a Raw Data File with an open end-user license. The data are available from the DGGS website: http://doi.org/10.14509/31286.
Major-oxide and trace-element geochemical data from rocks collected in 2015 in the Wrangellia mineral assessment area, Alaska
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Late Triassic mafic to ultramafic intrusions in the Wrangellia terrane are host to magmatic sulfide nickel-copper-cobalt and platinum-group element (PGE) mineralization. DGGS's mineral-resources group carried out a geologic mapping project in the eastern Denali Highway region between Watana Creek and Paxson from July 29 through August 7, 2015. This project is part of a multi-year effort focusing on improving the publicly available geological and geochemical data and assessing the mineral potential of the less-explored extension of the western Wrangellia terrane; other data resulting from this project include geophysical surveys and several geochemical datasets. This program of geologic mapping and rock sampling was conducted as part of the State of Alaska's Strategic and Critical Minerals Assessment project, an initiative designed to evaluate Alaska's potential for rare-earth elements, PGEs, and other similarly supply-challenged resources. Highlights of this project include identification, sampling, and characterization of a broad section of Wrangellia stratigraphy, including Late Triassic ultramafic and mafic intrusions thought to be a part of the Ni-Cu-Co-PGE- and Cu-Ag-mineralized Wrangellia large igneous province. This dataset includes four samples with high copper values (1.6 to 4.62 percent) and elevated silver values (10.15 to 18.25 ppm) and two samples have elevated copper (1,400 and 4,610 ppm); those samples are scattered throughout the area. Two samples from the Caribou Dome area show elevated platinum (0.113 and 0.101 ppm) and palladium (0.141 and 0.193 ppm). The analytical data tables associated with this report are being released in digital format as comma-delimited text (CSV) files.
Major-oxide, minor-oxide, and trace-element geochemical data from rocks collected in the Alaska Highway corridor, Mount Hayes, Tanacross, and Nabesna quadrangles, Alaska, in 2006, 2008, 2009, and 2010
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Geologists from the Alaska Division of Geological & Geophysical Surveys (DGGS) and the University of Alaska Fairbanks (UAF) carried out geologic field surveys, including bedrock mapping and sampling, in the Alaska Highway Corridor from 2006 through 2010. The fieldwork provides basic information critical to building an understanding of Alaska's geology and is part of a broader, integrated program that includes airborne geophysical surveys, bedrock and surficial mapping, a mineral-resource assessment, a geologic-hazards assessment, and other geological studies. This publication contains descriptive, location, and analytical information for samples collected in the Mount Hayes, Tanacross, and Nabesna quadrangles, Alaska, in the summers of 2006, 2008, 2009, and 2010. Additional analytical data for samples collected in the Mount Hayes Quadrangle in the summers of 2006 and 2007 were published in a separate report. During the field seasons covered by this report, rock samples were collected for geochemical trace-element and whole-rock (major- and minor-oxide and petrogenetically important trace-element) analyses. Rock sample location coordinates are presented in decimal degree latitude and longitude based on the North American Datum of 1927 (NAD 27) for Alaska. Brief sample descriptions are based principally on field observations with some thin-section details added.
Major-oxide, minor-oxide, and trace-element geochemical data from rocks collected in 2008 in the eastern Bonnifield mining district, Fairbanks and Healy quadrangles, Alaska
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Mineral-resources personnel from the Alaska Division of Geological & Geophysical Surveys carried out a geological field survey, including mapping and sampling, in the eastern part of the Bonnifield mining district in the Fairbanks A-1 and A-2, and the Healy D-1 and D-2 quadrangles, Alaska, from June 16 through July 18, 2008. The fieldwork provides basic information critical to building an understanding of Alaska's geology and is part of an integrated program of airborne geophysical surveys followed by geological mapping. Specifically, this work provides geologic context for geophysical surveys conducted in 2006. To represent a typical lithology, igneous or possible meta-igneous samples were collected and analyzed for major- and minor-oxide and petrogenetically important trace elements as a supplement to previously published geochemical data. The analyses were used to determine composition of the samples as well as potential original tectonic setting. Radiometric age analyses from some of these rocks have been published. Interpretation and synthesis of this data has been presented in professional and trade meetings. The analytical tables associated with this data release are available in digital format as comma-separated value (CSV) files.
Geochemical, major-oxide, minor-oxide, trace-element and carbon data from rocks collected in 2011 in the Moran area, Tanana and Melozitna Quadrangles, Alaska
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Mineral-resources personnel from the Alaska Division of Geological & Geophysical Surveys carried out a geologic field survey, including mapping and sampling in the Moran area in the Tanana A-6 and B-6 quadrangles, and the Melozitna A-1, A2, B-1, and B-2 quadrangles, Alaska from June 17 to August 15, 2011. The fieldwork provides basic information critical to building an understanding of Alaska geology and is part of an integrated program of airborne geophysical surveys followed by geologic mapping. During 2011, 212 rock samples were collected for geochemical trace-element analysis, 58 rock samples were collected for whole-rock (major- and minor-oxide and petrogenetically important trace elements tables) analyses, and two samples were collected for analysis of non-carbonate carbon content. Additionally, 352 polished rock slabs were analyzed for whole-rock and petrogenetically important trace elements.
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