This report and digital data release presents 209 new geochemical analyses on historic U.S. Bureau of Mines (USBM) samples, including 90 rock, 9 stream sediment, 14 soil, and 96 heavy mineral concentrate (pan concentrate) samples. These samples were originally collected by the USBM as part of their search for radioactive mineral deposits in the northern Darby Mountains, eastern Seward Peninsula, Alaska 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.

This report and digital data release presents 40 new geochemical analyses on historic U.S. Bureau of Mines (USBM) samples, including 33 rock and 7 heavy mineral concentrate (pan concentrate) samples. These samples were originally collected by the USBM as part of their critical and strategic minerals project, which investigated the rare-earth-element and uranium mineral potential of the Zane Hills area, northwestern Alaska. 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.

This report and digital data release presents 26 new geochemical analyses on historic U.S. Bureau of Mines (USBM) samples, including 4 rock, 9 stream sediment, 3 soil, and 10 heavy mineral concentrate (pan concentrate) samples. These samples were originally collected by the USBM to investigate rare-earth-element occurrences associated with the Kook Lake intrusive complex, Sitka Quadrangle, Alaska. 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.

This report and digital data release presents 12 new geochemical analyses on historic U.S. Bureau of Mines (USBM) samples, including 6 rock, 4 stream sediment, and 2 heavy mineral concentrate (pan concentrate) samples. These samples were originally collected by the USBM to follow up reported tungsten anomalies in the VABM Bend area, Charley River and Eagle quadrangles, east-central Alaska. 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.

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.

This report and digital data release presents 90 new geochemical analyses on historic U.S. Bureau of Mines (USBM) samples, including 56 rock, 16 sediment, 5 soil, and 12 heavy mineral concentrate (pan concentrate) samples, as well as 1 sample of indeterminate type. Some of these samples were originally collected by the USBM as part of their mineral investigations in the Porcupine River drainage, northeastern 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.

This report and digital data release presents 326 new geochemical analyses on historic U.S. Bureau of Mines (USBM) samples, including 106 rock, 164 stream sediment, and 56 heavy mineral concentrate (pan concentrate) samples. These samples were originally collected by the USBM as part of a mineral-reconnaissance project in the Selawik Hills area of northwestern Alaska. 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.

This report and digital data release presents 82 new rock geochemical analyses on historic U.S. Bureau of Mines (USBM) samples. These samples were originally collected by the USBM as part of their critical and strategic minerals project, which investigated tin occurrences associated with the Ohio Creek pluton, south-central Alaska. 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.

During the 2017 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-4, B-5, and C-5 quadrangles. The project area is about 30 miles west of the Pogo gold mine and covers the currently active Montecristo and Uncle Sam gold-exploration properties. The goal of DGGS's work in this area is to conduct a mineral-resource assessment and to build an improved understanding of the area's geology and controls on gold mineralization to facilitate industry exploration targeting. This report is based on 17 days of fieldwork completed June 23-July 3, July 18-20, and August 11-13, 2017 by two to seven DGGS geologists. The study area is bound by the Pogo Road to the southeast and the Trans-Alaska Pipeline access road to the southwest (fig. 1); the crew accessed the interior of the study area by helicopter, all-terrain vehicles, and foot. The Richardson area is characterized by moderate-relief hills and boreal spruce and deciduous forest typical of interior Alaska. Loess deposits of variable thickness blanket the area, and deposits of forest-covered eolian sand, including well-formed dune fields, cover the southeastern quadrant of the area along Shaw Creek. Rock outcrop accounts for much less than one percent of the study area, consequently, the majority of rock samples were collected from pits, up to 1-meter-deep, dug with shovels into rocky colluvial deposits below the surficial loess or sand. Highlights of geochemical results include 2.67 parts per million (ppm) gold and 68.4 ppm silver from a float sample collected at the Naosi prospect. An in-place, surface rock sample collected from the Mon prospect area assayed 2.42 ppm gold and 23 ppm silver. Both prospects are part of the Montecristo property. Whole-rock analyses indicate the granitic dikes that are abundant on the Montecristo and Uncle Sam properties are peraluminous granites of arc character. They most closely resemble the Early Cretaceous peraluminous felsic dikes documented in the southeastern Richardson district by Graham (2002); they are less similar (less peraluminous) to the ca. 90 Ma Gold Run intrusion (Graham, 2002) and Birch Lake pluton (Burns and others, 1993). Amphibolite samples are basaltic in composition and have island-arc tholeiite or mid-ocean ridge basalt character, similar to unit MzPza amphibolites in the Salcha River-Pogo area (Werdon and others, 2004). 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/10.14509/29779).