This data release is part of a 2016-2019 study on the geology, geochemistry and geochronology of ore systems in the eastern Yukon-Tanana Upland region, Alaska. Whole rock chemistry was conducted on 185 samples, mostly from Au prospects, with lesser samples from porphyry Cu prospects. Geographically, most samples are from gold prospects near the Pogo Au mine and east to Black Mountain in the Big Delta quadrangle. Fewer samples are from prospects in the Eagle and Tanacross Quadrangles. Samples were submitted to the USGS contract laboratory and analyzed for select trace elements and gold. Sixty elements were determined by inductively coupled plasma-optical emission spectroscopy-mass spectroscopy (ICP-OES-MS), sodium peroxide fusion (ICP-60). Gold was determined by lead fusion fire assay.

In conjunction with hosting field trips for the Association of American State Geologists 2016 annual meeting in Girdwood, Alaska, Alaska Division of Geological & Geophysical Surveys (DGGS) staff collected rock samples and obtained geochemical analysis from several readily accessible, but relatively unstudied outcrops. Samples were collected from Turnagain Arm (mile 104 Seward Highway), Whittier, Crow Pass, and Panorama Mountain (roughly mile 217 Parks Highway). Mineralized samples from veins and veinlets in granitic rocks from the Crow Pass and Whittier sites contain anomalous levels of gold ranging from 0.129 to 0.650 parts per million (ppm). Although none of the samples are from areas open to mineral entry, geochemical analyses of rocks from these localities may support interpretation of regional mineral-distribution trends. The analytical data tables associated with this report are available in digital format as comma-separated value (CSV) files. Additional details about the organization of information are noted in the accompanying metadata file. All files can be downloaded from the DGGS website (http://doi.org/10.14509/29725).

This set of data files contains analyses of samples representing Triassic units (Shublik and Ivishak Formations and Karen Creek Sandstone) in Alaska. The samples were collected from 20 outcrop localities in northeastern Alaska. The data set includes total organic carbon (TOC) and geochemical data from inductively coupled plasma-optical emission spectroscopy-mass spectroscopy (ICP-OES-MS) and portable X-ray fluorescence (p-XRF). The data presented here are described and interpreted in a paper titled "Facies Variation within Outcrops of the Triassic Shublik Formation, Northeastern Alaska".

Geochemical data from samples collected in 2022 for the Mount Harper geologic mapping project, Big Delta, Mount Hayes, and Eagle quadrangles, Alaska, Raw Data File 2023-24, presents whole-rock and major- and trace-element geochemistry of rock samples collected to support geologic mapping and mineral exploration in the Mount Harper area of the Melozitna mining district. During the 2022 field season, geologists from the Alaska Division of Geological & Geophysical Surveys (DGGS) conducted 1:100,000-scale bedrock geologic mapping of ~3,100 mi2 (~8,000 km2) within the Big Delta, Mount Hayes, and Eagle quadrangles. This project aims to produce more detailed and modern geologic maps and supporting datasets to promote mineral resource exploration in eastern Interior Alaska. The project area includes known gold (Au) mineralization, recently explored in the Richardson mining district, including the SAM project and the nearby Democrat Lode and associated prospects, and in the Goodpaster mining district at the LMS and Healy intrusion-related gold prospects. The Mount Harper area hosts a cluster of molybdenum (Mo) and tungsten (W) prospects, including porphyry Mo and W skarn styles, both of which have had industry interest over the decades. Ultramafic rocks occur in the South Fork and Volkmar river drainages; these bodies have an as-yet poorly understood potential to host platinum group elements (PGE), chrome (Cr), cobalt (Co), and nickel (Ni) resources. The DGGS map area includes a section of pre-Mississippian to Permian metasedimentary and metaigneous rocks and Triassic to Paleogene intrusive and volcanic rocks. Major- and trace-element geochemistry for these rocks was analyzed to further our understanding of the resources in the area, including distinguishing between igneous and sedimentary protoliths for metamorphic rocks and characterizing and differentiating Mesozoic and Cenozoic magmatic events in the area. Highlights of this geochemical report include sampling of the Healy and LMS projects and multiple prospects on Mount Harper and elsewhere in the map area. Sample 22Z336, collected south of the Brink prospect, yielded 1.52 ppm Au and 500 ppm W. A few samples collected at the LMS prospect yielded elevated silver (Ag) concentrations (for example, sample 22Z409 yielded up to 12.95 ppm). Additionally, sample 22Z406 yielded 1.48 ppm Au, 7.65 ppm Ag, and 1,787 ppm arsenic (As). Samples collected at Larsen Ridge/Lucky 13 prospect near the top of Mount Harper yielded high Ag and W values. For example, 22Z271 (a massive quartz vein) yielded 18.87 ppm Ag and 1,100 ppm W, 22TJN157 (a skarn) yielded 5.75 ppm Ag, 2,348 ppm copper, 4,422 ppm manganese (Mn), and 600 ppm W, and 22Z270 (a granite) yielded 2,356 ppm Mo and 200 ppm W. The Richardson mining district has been previously sampled by DGGS. 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/10.14509/31089.

The State of Alaska's Strategic and Critical Minerals (SCM) Assessment project, a State-funded Capital Improvement Project (CIP), is designed to evaluate Alaska's statewide potential for strategic and critical mineral resources. The SCM Assessment project is being implemented by the Alaska Division of Geological & Geophysical Surveys (DGGS), and involves obtaining new airborne-geophysical, geological, and geochemical data. For the geochemical part of the SCM Assessment project, thousands of geochemical-sample analyses and locations from historical U.S. Bureau of Mines (USBM), U.S. Geological Survey (USGS), Bureau of Land Management (BLM), DGGS, Alaska Territorial Department of Mines, Alaska Division of Mines and Minerals, and Bureau of Indian Affairs (BIA) reports are being compiled into digital format by DGGS. The objective is to update the State of Alaska's statewide digital geochemical database in order to more clearly identify areas with SCM potential. For this report, DGGS digitally compiled sample and analyses documentation, geochemical assays, and location information for more than 4,400 historical samples that were were originally collected to investigate occurrences of strategic and critical elements throughout Alaska.

This data release is the result of a hydrogeochemical sampling campaign during summer 2021 to investigate whether high resolution geochemical analysis of waters for element chemistry can be used as an exploration tool for identifying gold-rich occurrences in parts of the Big Delta B-1 and B-2 quadrangles, within the Yukon-Tanana Upland region, Alaska. Historical USGS conventional stream sediment geochemical data yielded variable indications of geochemical anomalies in conventional stream sediment geochemistry results, probably related to relative exposure of mineralized rock. Previous studies of waters in the Pogo area (western part of current study) utilized conventional analytical methods not capable of measuring low concentrations of many elements (Wang et al., 2005). In the current study, water samples were collected from 36 stream sample sites, with a focus on streams around Black Mountain to the east and the Pogo Au deposit area to the west. Both areas have known gold-rich mineral occurrences. In the eastern Black Mountain area, this included the Gray Lead, Blue Lead, and Michigan prospects, among others (U.S. Geological Survey, 1996). Sampling in the Pogo area was restricted to streams outside Leise Creek area due to anthropogenic disturbance as part of mining. Stream water samples were collected in 2021 and analyzed for cation and anion concentrations using high-resolution ICP-MS for cations and ion chromatography (IC) for anions.

The State of Alaska's Strategic and Critical Minerals (SCM) Assessment project, a State-funded Capital Improvement Project (CIP), is designed to evaluate Alaska's statewide potential for strategic and critical mineral resources. The SCM Assessment project is being implemented by the Alaska Division of Geological & Geophysical Surveys (DGGS), and involves obtaining new airborne-geophysical, geological, and geochemical data. For the geochemical part of the SCM Assessment project, thousands of geochemical-sample analyses and locations from historical U.S. Bureau of Mines (USBM), U.S. Geological Survey (USGS), Bureau of Land Management (BLM), DGGS, Alaska Territorial Department of Mines, Alaska Division of Mines and Minerals, and Bureau of Indian Affairs (BIA) reports are being compiled into digital format by DGGS. The objective is to update the State of Alaska's statewide digital geochemical database in order to more clearly identify areas with SCM potential. For this report, DGGS digitally compiled sample and analyses documentation, geochemical assays, and location information for more than 22,500 historical samples that were originally collected to investigate occurrences of strategic and critical elements throughout Alaska.

Data for 819 pan concentrated stream-sediment samples, nonmagnetic heavy-mineral concentrate (HMC) samples, and chemical data for 93 of HMC samples. The samples were collected in 2004-2008 as part of a reconnaissance geochemical geological survey of drainage basins mostly in the Taylor Mountains 1:250,000-scale quadrangle in southwestern Alaska. Samples were collected from first- or second-order streams, as shown on USGS 1:63,360-scale maps. The data reported here are from hand lens inspection of the panned concentrate samples in the field, microscopic examination of the non-magnetic fraction of the HMC samples in the lab, and chemical analyses by Inductively Coupled Plasma-Atomic Emission Spectrometry-Mass Spectrometry (ICP-AES-MS) of selected nonmagnetic HMC samples.

During the 2018 field season, geologists from the Alaska Division of Geological & Geophysical Surveys (DGGS) conducted geologic mapping and sampling of part of the Richardson mining district southeast of Fairbanks, including parts of the Big Delta B-5 and B-6 quadrangles. The project area has produced approximately 122,000 ounces of gold (Singh and others, 2017), mostly from placer mines, and it includes the Richardson, Tower, and Hilltop lode gold exploration properties. Rock outcrop accounts for much less than one percent of the study area, consequently, many of the rock samples were collected from up to 1-meter-deep pits dug with shovels into rocky colluvial deposits below the surficial loess. Highlights of the geochemical results include 43.3 and 9.77 parts per million (ppm) gold sampled from arsenopyrite-bearing quartz veins at the Hilltop prospect. At the Democrat prospect, formerly the site of small-scale mining, a sample of sulfide-rich material returned 3,790 ppm silver and 4.72 ppm gold. Other samples from the Democrat prospect assayed 6.81 and 5.01 ppm gold. The analytical data tables associated with this report are available in digital format as comma-separated value (CSV) files. All files can be downloaded from the DGGS website (http://doi.org/10.14509/30119).

This data set compiles the major and trace element chemistry of rock samples collected by the U.S. Geological Survey (USGS) at Bokan Mountain, located in the southern part of Prince of Wales Island, southeastern Alaska. Bokan Mountain was formed by an Early Jurassic peralkaline igneous complex that intruded into lower Paleozoic rocks of the Alexander terrane of southeast Alaska. The pluton and surrounding country rocks host numerous mineral deposits and occurrences, including heavy rare earth element (HREE)-rich pegmatites and felsic dikes, as well as mineral deposits rich in uranium, thorium, HREE, and fluorine. The Ross-Adams mine on Bokan Mountain exploited a uranium-thorium deposit intermittently from the late 1950s to 1971, and remains the only uranium producer in Alaska. Recent exploration by Ucore Rare Metals Inc. (http://ucore.com/) at Bokan Mountain has focused on the Dotson and I and L Zones, which together form a 2.5-km-long, 50 m-wide zone of thin felsic dikes and pegmatites (each rarely more than 2-m-wide) that are enriched in rare earth elements (REE). Ucore Rare Metals has reported an inferred resource for the combined zones as 5.275 million metric tons of ore at 0.654 percent total REE oxides, using a cutoff of 0.4 percent total REE oxides; about 40 percent of the total REE oxides in these dikes and pegmatites are the HREE (http://ucore.com/Ucore_43-101.pdf). This data release provides the analytical results of 153 rock hand samples collected by USGS geologists during site visits to Bokan Mountain in 2010, 2011, and field studies during 2014. The samples represent a variety of rock types associated with the Bokan Mountain igneous complex, including mineral deposits, prospects and occurrences, along with examples of unaltered intrusions of the pluton. The samples were analyzed for 55 major and trace elements using inductively coupled plasma-atomic emission spectrometry (ICP-AES) and inductively coupled plasma-mass spectrometry (ICP-MS) and also analyzed for major elements using wavelength dispersive x-ray fluorescence spectrometry (WDXRF). This data set is provided for future use in geologic, exploration, and environmental background studies of Bokan Mountain and its mineral deposits.