Major-oxide and trace-element geochemical data from rocks collected in 2018 for the Northeast Tanacross project, Tanacross C-1, C-2, D-1, and D-2 quadrangles, Alaska

From June 19 through July 15, 2018, geologists from the Alaska Division of Geological & Geophysical Surveys (DGGS) carried out a geologic mapping and geochemical sampling project in the Northeast Tanacross map area, Tanacross D-1 and parts of C-1 and D-2 quadrangles. This area lies in the Yukon-Tanana terrane on the boundary between the Fortymile and Lake George Assemblages (Dusel-Bacon and others, 2006). It encompasses well-documented porphyry Cu-Mo-Au deposits including Taurus, Fishhook (otherwise known as SW Pika), and Pika Canyon, and is adjacent to the Fortymile Mining District. Highlights of this DGGS Northeast Tanacross geochemical report include identification, sampling, and characterization of the Taurus and Bluff prospects. This dataset has 20 samples with gold in excess of 0.1 ppm in several different locations, including a sample with 2.67 parts per million (ppm) Au (18MBW082) collected north of Taurus West, a sample with 1.2 ppm Au (18RN373) in drill core from the Bluff prospect, and 17 samples with 0.1 to 0.327 ppm Au (highest value reported for 18RN276) in drill cores from the Taurus prospect. Additionally, two samples with over 50 ppm Ag (18ET102 and 18ET307) were collected between the Pika Canyon and Fishhook Prospects. The DGGS map area includes a section of Mississippian to Devonian metasedimentary and metavolcanic rocks as well as Jurassic(?) to Tertiary 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 in digital format as comma-separated value (CSV) files. All files can be downloaded from the DGGS website (http://doi.org/10.14509/30113).