Geologists from the Alaska Division of Geological & Geophysical Surveys (DGGS) and University of Alaska carried out a two-part geologic mapping and geochemical sampling project in the Tok River area of the Tanacross A-5 and A-6 quadrangles (June 12-26 and July 8-26). The Tok River area is adjacent to the Delta mineral belt volcanogenic massive-sulfide (VMS) district, the Peak gold-silver-copper skarn, and the structurally controlled gold and antimony mineralization in the Stibnite Creek and White Gold areas. The Tok River project area includes the Noah (also called Hona) prospect, an intrusion-related copper prospect. The combination of insufficient detailed geologic mapping, historical and current industry interest in the adjacent mineralized areas, and the recently published geophysical data prompted the DGGS Mineral Resources section to work in this area. Highlights of this DGGS Tok River geochemical report include identification, sampling, and characterization of prospects without previously available public data, including the Eagle, Dall, Parton, and Jacqueline prospects. This dataset has 22 samples with gold in excess of 0.5 ppm in several different locations, including a sample with 9.78 ppm Au (16ET254, Shalovsky vein), a sample with 6.25 ppm Au from nearby Hona porphyry (16ET312), a sample containing 1.22 ppm Au from a vein within schist south of Dry Tok Creek (16KS255), and a sample with 1.315 ppm Au from drill hole WG-11-05 (16RN165B, Eagle trend). Major- and trace-element geochemical analyses were obtained for the metamorphic rocks to distinguish between igneous and sedimentary protoliths and for igneous rocks to characterize and differentiate Mesozoic and Cenozoic rocks in the area.

The Tok project area is adjacent to the Delta mineral belt volcanogenic massive-sulfide (VMS) district, the Peak gold-silver-copper skarn, and structurally controlled gold and antimony mineralization in the Stibnite Creek and White Gold areas. The project area also includes the Noah prospect, an intrusion-related copper prospect. Whereas the Delta mineral belt has been extensively mapped and explored, the detailed mapping does not continue into the 2015 Tok project area. In this area, only reconnaissance mapping has been conducted. The combination of a lack of detailed mapping, the industry interest in the adjacent areas, and the geophysical data findings prompted the Alaska Division of Geological & Geophysical Surveys (DGGS) mineral resources group to work in this area. DGGS geologists carried out a geologic reconnaissance mapping project in the Tanacross A-5, A-6, and parts of adjacent quadrangles from June 18 through 28, 2015. This dataset includes two samples with elevated gold, 1.3 and 14.5 ppm, accompanied with very high arsenic values (both over 10,000 ppm) and antimony values (352 and 97.4 ppm). The sample containing 14.5 ppm Au, 305 ppm Bi and 11.1 ppm Te (15ET026) was collected from sulfide pods in schist adjacent to a granitic intrusion near the Noah prospect, and the sample containing 1.3 ppm Au (15KS007) was collected from quartz veining in a fault zone. Major element chemistry has been obtained on the metamorphic rocks to distinguish between igneous and sedimentary protoliths of the rocks using criteria proposed by Dashevsky and others (2003) and on igneous rocks to characterize and differentiate Mesozoic and Cenozoic igneous deposits in the area. The analytical data tables associated with this report are being released in digital format as comma-delimited text (CSV) files.

The Tok project area is adjacent to the Delta mineral belt volcanogenic massive-sulfide (VMS) district, the Peak gold-silver-copper skarn, and structurally controlled gold and antimony mineralization in the Stibnite Creek and White Gold areas. The project area also includes the Noah prospect, an intrusion-related copper prospect. Whereas the Delta mineral belt has been extensively mapped and explored, the detailed mapping does not continue into the 2015 Tok project area. In this area, only reconnaissance mapping has been conducted. The combination of a lack of detailed mapping, the industry interest in the adjacent areas, and the geophysical data findings prompted the Alaska Division of Geological & Geophysical Surveys (DGGS) mineral resources group to work in this area. DGGS geologists carried out a geologic reconnaissance mapping project in the Tanacross A-5, A-6, and parts of adjacent quadrangles from June 18 through 28, 2015. This dataset includes two samples with elevated gold, 1.3 and 14.5 ppm, accompanied with very high arsenic values (both over 10,000 ppm) and antimony values (352 and 97.4 ppm). The sample containing 14.5 ppm Au, 305 ppm Bi and 11.1 ppm Te (15ET026) was collected from sulfide pods in schist adjacent to a granitic intrusion near the Noah prospect, and the sample containing 1.3 ppm Au (15KS007) was collected from quartz veining in a fault zone. Major element chemistry has been obtained on the metamorphic rocks to distinguish between igneous and sedimentary protoliths of the rocks using criteria proposed by Dashevsky and others (2003) and on igneous rocks to characterize and differentiate Mesozoic and Cenozoic igneous deposits in the area. The analytical data tables associated with this report are being released in digital format as comma-delimited text (CSV) files.

Raw Data File 2022-4, Geochemical data from samples collected in 2021 for the Taylor Mountain project, Tanacross and Eagle quadrangles, Alaska, presents whole-rock trace-element and major- and minor-oxide geochemistry for samples collected to support geologic mapping and mineral exploration. During the 2021 field season, geologists from the Alaska Division of Geological & Geophysical Surveys (DGGS) conducted 1:100,000-scale bedrock geologic mapping of ~2,600 mi2 (~6,900 km2) within the Tanacross and Eagle quadrangles. The field area for the Taylor Mountain project is within a 50-mile radius of Chicken, Alaska. The project area is of current and historic interest for potential mineral resource development, including quartz vein gold (Au) mineralization, placer Au deposits, granite-hosted tin (Sn) mineralization, and intrusion-related copper (Cu)-Au deposits. Prospects in the area include Tweeden, Lilliwig Creek lode, and others. Much of the field area was mapped at 1:250,000 scale by the U.S. Geological Survey (USGS) in the 1960s (Foster, 1970, 1976). This project aims to produce more detailed and modern geologic maps and supporting datasets that will promote mineral resource exploration in eastern interior Alaska. Highlights of this DGGS eastern Taylor Mountain geochemical report include locating and sampling of the Tweeden, Lilliwig Creek lode, Moose Creek, and Fish prospects. Four samples collected at Tweeden returned gold (Au) values over 1 ppm: 21ET247-2.66 ppm Au; 21ET248-1.75 ppm Au; 21ET249-1.34 ppm Au; and 21ET250-1.3 ppm Au. A greenstone sample collected at Kechumstuk Mountain (21MLB195) returned a Cu concentration of 2,960 ppm. The DGGS map area includes a section of pre-Mississippian to Permian metasedimentary and metaigneous rocks as well as Triassic to Paleogene intrusive and volcanic rocks. Major- and trace-element geochemistry was analyzed for metamorphic rocks to distinguish between igneous and sedimentary protoliths, and for igneous rocks to characterize and differentiate Mesozoic and Cenozoic magmatic events in the area. The analytical data tables associated with this report are available through the Alaska Geochemistry database (https://maps.dggs.alaska.gov/geochem). For a direct link to this data release, see http://doi.org/10.14509/30843.

From June 12-21, 2017, the Alaska Division of Geological & Geophysical Surveys (DGGS) geologists carried out geologic mapping and geochemical sampling in the northeastern Tanacross D-1, and parts of the C-1, and D-2 quadrangles. The project area lies within the Yukon-Tanana Uplands, and encompasses the boundary between Fortymile and Lake George assemblages. It includes porphyry copper-molybdenum-gold deposits and prospects including: Taurus, Fishhook (also known as SW Pika), and Pika Canyon, and is adjacent to the Fortymile Mining District to the north. Highlights of this geochemical report include sampling and characterization of the Pika Canyon, Fishhook, and Taurus prospects. This dataset contains four samples with gold in excess of 0.1 parts per million (ppm) in several different locations, including two samples from Fishhook with 2.15 ppm and 0.697 ppm gold, respectively (17MBW119, 17MBW130), and a sample with 4,420 ppm silver and greater than 30 percent lead (17MLW002) collected nearby Pika Canyon. The DGGS Tanacross project area includes a section of Paleozoic and Mississippian- to Devonian-age, metasedimentary and metavolcanic rocks, as well as Jurassic(?) to Tertiary intrusive and volcanic rocks. Major- and trace-element geochemical analyses were obtained for metamorphic rocks to distinguish between igneous and sedimentary protoliths, and for igneous rocks to characterize and differentiate Mesozoic and Cenozoic rocks in the area. 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/10.14509/29778).

This data release is part of a study designed to test geochemical methods that best delineate known mineral deposits in the northeast part of the Tanacross 1° x 3° quadrangle, within the Yukon-Tanana Upland region, Alaska. The total area sampled is about 3,200 km2. Extensive tundra cover and patchy spruce/alder vegetation and very limited outcrop exposure characterize the area. Soils and stream sediments contain mixtures of weathered bedrock, sand derived from dunes developed during the Pleistocene, and volcanic ash deposits from the 1.2 Ky eruption of the nearby Mount Churchill volcano. Several mineral deposits are known in the area, including the Late Cretaceous to earliest Tertiary porphyry Cu (+/-Mo-Au) deposits at Taurus, Bluff, and Oreo; and poorly understood epithermal(?) Cu-Au (+/- Pb-Zn) deposits at Pika, Fishhook, and Pushbush. Stream water and sediment samples were collected near these occurrences, as well as in surrounding areas, to determine methods that most effectively enhance geochemical signals related to mineralization. Sediment samples were collected during two sampling campaigns (2017 and 2018). Each sample was dried, homogenized, and split into multiple aliquots. One aliquot of sediment was subsequently sieved to recover the minus-80 mesh portion of the sample, whereas a second was sieved to recover the minus-230 mesh portion of the sample. Both aliquots were analyzed by three techniques, all of which included ICP-OES/ICP-MS analysis following (1) sodium peroxide fusion, 2) leaching by aqua regia; and 3) leaching by cold hydroxylamine-HCL. Stream water samples were collected from select sites in August 2018 and analyzed for cation and anion concentrations using high-resolution ICP-MS for cations and Ion Chromatography (IC) for anions.

This data release is part of a study designed to test geochemical methods that best delineate known mineral deposits in the northeast part of the Tanacross 1° x 3° quadrangle, within the Yukon-Tanana Upland region, Alaska. The total area sampled is about 3,200 km2. Extensive tundra cover and patchy spruce/alder vegetation and very limited outcrop exposure characterize the area. Soils and stream sediments contain mixtures of weathered bedrock, sand derived from dunes developed during the Pleistocene, and volcanic ash deposits from the 1.2 Ky eruption of the nearby Mount Churchill volcano. Several mineral deposits are known in the area, including the Late Cretaceous to earliest Tertiary porphyry Cu (+/-Mo-Au) deposits at Taurus, Bluff, and Oreo; and poorly understood epithermal(?) Cu-Au (+/- Pb-Zn) deposits at Pika, Fishhook, and Pushbush. Stream water and sediment samples were collected near these occurrences, as well as in surrounding areas, to determine methods that most effectively enhance geochemical signals related to mineralization. Sediment samples were collected during two sampling campaigns (2017 and 2018). Each sample was dried, homogenized, and split into multiple aliquots. One aliquot of sediment was subsequently sieved to recover the minus-80 mesh portion of the sample, whereas a second was sieved to recover the minus-230 mesh portion of the sample. Both aliquots were analyzed by three techniques, all of which included ICP-OES/ICP-MS analysis following (1) sodium peroxide fusion, 2) leaching by aqua regia; and 3) leaching by cold hydroxylamine-HCL. Stream water samples were collected from select sites in August 2018 and analyzed for cation and anion concentrations using high-resolution ICP-MS for cations and Ion Chromatography (IC) for anions.

Mineral-resources personnel from the Alaska Division of Geological & Geophysical Surveys conducted reconnaissance stream-sediment and pan-concentrate sampling in the Melozitna Mining District, Tanana and Melozitna quadrangles, from July 25 to August 13, 2011. This helicopter-supported sampling project was part of a statewide assessment of Alaska's potential for rare-earth element (REE) mineralization, and was funded by the Rare Earth Elements and Strategic Minerals Assessment capital improvement project. During this field project, 32 stream sediment and 28 heavy-mineral pan concentrate samples were collected for geochemical analysis (geochemical trace elements and rare earth elements). An additional historic U.S. Bureau of Mines sample from the area was also analyzed as part of this report. Highlights of the DGGS sampling project include documenting new gold-bearing drainages and identifying several samples with high REE values.

This report and digital data release presents 131 new geochemical analyses on historic U.S. Bureau of Mines (USBM) samples, including 86 rock and 42 heavy mineral concentrate (pan concentrate) samples, as well as 3 samples of indeterminate type. Some of these samples were originally collected by the USBM from the Ray River watershed, and the Kanuti and Hodzana Rivers uplands, central Alaska, and a portion of the samples were collected as part of the National Uranium Resource Evaluation. Historic USBM sample materials were retrieved by DGGS from the DGGS Geologic Materials Center (GMC), where the USBM samples were transferred as part of the federally funded Minerals Data and Information Rescue in Alaska (MDIRA) program in the late 1990s and early 2000s. The text and analytical data and tables associated with this report are being released in digital format as PDF files and .csv files. We provide analytical data, detection limits and, when available, the method documentation provided to us by the lab. We also provide the sample location in geographic coordinates, the sample material cited by the originating literature, a reference to the originating report, and the type of sample material that was obtained from the archive and sent to the lab.