Mineral Resources Section personnel from the Alaska Division of Geological & Geophysical Surveys (DGGS) carried out a geologic 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 geologic mapping. Specifically, this work provides geologic context for geophysical surveys conducted in 2006. Interpretation and synthesis of this data has been presented in professional and trade meetings. This report and associated geologic map data are preliminary, have not undergone rigorous peer review, and will be superseded by a subsequent Report of Investigations map and report that will be issued later in 2016. The objective of the eastern Bonnifield project is to produce a 1:50,000-scale geologic map to foster a better understanding of the area's geology and mineral potential. Although DGGS concentrated on mapping the Paleozoic metamorphic rocks that host the volcanogenic massive sulfide deposits (VMS) and Mesozoic igneous rocks associated with Au-Ag-As-Sb veins, we also studied the Tertiary sedimentary section, which could contain coal resources. The geologic map data are available in digital format as ESRI shapefiles.

Bedrock geologic map of the northern Fairbanks mining district, Circle Quadrangle, Alaska, Preliminary Interpretive Report 2022-2, presents whole-rock trace-element geochemistry of Nb, Rb, Sr, Y, Zr for samples collected to support geologic mapping and mineral exploration in the northern Fairbanks mining district. 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/10.14509/30891.

Miscellaneous Publication 172, Bedrock geologic map database of the Caribou Creek area, Big Delta C-4 and D-4 quadrangles, east-central Alaska, presents 1:25,000 scale geologic mapping of the Caribou Creek area in the Big Delta C-4 Quadrangle, east-central Alaska. The Caribou Creek area is known for significant placer gold but no known lode gold source. Additionally, it is one of the few regions in interior Alaska where native bismuth has been reported in placers. During an 11-week field campaign in the summer of 2002, an area of approximately 200 km2 was mapped at a 1:25,000 scale to delineate the area's geologic rock units, identify structural elements and their relative orientation, and collect rock samples for the geochemical and geochronological analysis needed to develop a model for the geological evolution of the area and potential source of the area's abundant placer gold. The resultant bedrock geologic map was published as a component of a University of Alaska master's thesis (Lessard, 2006). This publication release provides a modern compilation of the thesis map's GIS data. The dataset contains geologic, structural, stratigraphic, and geochronologic data organized according to the GeMS and AK GeMS mapping schemas. The geodatabase and ESRI fonts and style files are available from the DGGS website: https://doi.org/10.14509/30866.

This map illustrates potential near-surface sources of geologic materials that may be useful for construction and other purposes. Field observations indicate that each geologic unit (for example, flood-plain alluvium) has a definite composition or range of composition. Therefore, the presence of material type is interpreted from the distribution of geologic units (Newberry and others, 1996 - PDF96-16). Assignment of Unified Soil Classes (Wagner, 1957) is based on visual observation and interpretation of the likely distribution of the materials; no grain-size analyses were performed. Descriptions of unconsolidated deposits are modified from Pewe and Bel (1975a-d) and Pewe and Bell (1976). This map is generalized and is not intended to show exact locations of specific materials.

Mineral Resources Section personnel from the Alaska Division of Geological & Geophysical Surveys (DGGS) carried out a geologic field mapping survey 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. The map area contains several significant polymetallic sulfide prospects and transects three metamorphic assemblages, which include the Healy Schist, Keevy Peak Formation, and the Totatlanika Schist. The fieldwork (June 16 through July 18, 2008) augments publically available 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. This raw data release provides petrographic thin section observations of 264 samples from the East Bonnifield Project rock collection. Project staff examined thin sections to better distinguish rock units, assist with evaluating the structural and stratigraphic relationships among the various lithologies, and to determine suitability for lithogeochemical and geochronological analysis. Observations in the data tables include lithologic classification, texture, mineral crystal structure, and mineral components. Users can access the complete report and digital data from the DGGS website: http://doi.org/10.14509/30171.

Report of Investigation 95-2B, Bedrock geologic map of the Circle mining district, Alaska, provides detailed (1:63,360-scale) interpreted bedrock mapping of portions of U.S. Geological Survey Circle B-2, B-3, B-4, C-2, C-3, and C-4 quadrangles. The area is part of the Circle mining district and adjacent to the Fairbanks mining district. This report includes detailed geologic, structural, stratigraphic, and geochronologic data. The complete report, geodatabase, and ESRI fonts and style files are available from the DGGS website: http://doi.org/10.14509/2515.