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.

Mineral-resources personnel from the Alaska Division of Geological & Geophysical Surveys carried out a geological field survey, including mapping and sampling near Livengood in the Livengood B-3 and B-4 quadrangles, Alaska from June 10 to June 30, 2010. 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. During 2010, 130 rock samples were collected for geochemical trace-element analysis, and 20 rock samples were collected for whole rock (major- and minor-oxide) analysis. Petrogenetically important trace elements for additional rock samples will be analyzed and published with the final map and report for this area.

The mineral-resources group from the Alaska Division of Geological & Geophysical Surveys (DGGS) carried out a geologic mapping project in the Talkeetna Mountains C-4, C-3, and B-4 quadrangles from July 23 through August 3, 2014. This project is a part of a multi-year project 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. This program of geologic mapping and rock sampling was conducted as part of the U.S. Geological Survey National Cooperative Geologic Mapping Program and the state of Alaska's Strategic Minerals Assessment project, an initiative designed to evaluate Alaska's potential for rare-earth elements, PGEs (platinum group elements), and other similarly supply-challenged resources. Highlights of this project include identification, sampling, and characterization of a broad section of the Wrangellia stratigraphy, including Late Triassic rocks of the Ni-Cu-Co-PGE- and Cu-Ag-mineralized Wrangellia large igneous province as well as modern geochemical characterizations of skarn, vein, and basalt-hosted Cu mineralization. This data set includes four samples with elevated gold, ranging from 0.5 to 0.875 ppm, with one of these samples also containing elevated Cu (1.18 percent). Twelve samples have elevated copper, ranging from 1000 to 7900 parts per million, and two samples contain a significant copper spike (13 and 19.65 percent) and elevated silver (42 and 48 parts per million). The analytical data tables associated with this report are being released in digital format as comma-delimited text (CSV) files.

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.

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, A-2, 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’s 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 (tables 1–3), 58 rock samples were collected for whole-rock (major- and minor-oxide and petrogenetically important trace elements) analyses, two samples were collected for analysis of non-carbonate carbon content, 439 polished rock slabs were analyzed for whole rock and petrogenetically important trace elements, and 26 samples were analyzed for rare earth elements.

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.

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).

Mineral-resources personnel from the Alaska Division of Geological & Geophysical Surveys conducted reconnaissance sampling of the William Henry Bay area in the Juneau C-4 and D-4 quadrangles, August 9-13, 2011. This sampling project was part of a statewide assessment of Alaska's potential for rare-earth element mineralization. During the William Henry Bay field project 46 rock, sediment, and heavy-mineral concentrate samples were collected for geochemical analysis (geochemical, major oxide, minor oxide, trace element, and rare earth elements).

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).