40Ar/39Ar data from the Tanacross D-1 and parts of the D-2, C-1, and C-2 quadrangles, Alaska

This report presents 40Ar/39Ar step-heating geochronology results for igneous and metamorphic rocks from the Alaska Division of Geological & Geophysical Surveys' (DGGS) geologic mapping project in the Northeast Tanacross map area in the Tanacross D-1 and parts of the D-2, C-1, and C-2 quadrangles, Alaska. Field samples were collected by the DGGS Mineral Resources section during detailed geologic mapping campaigns in 2017 and 2018. The Northeast Tanacross map area lies within the Yukon-Tanana Upland and covers the boundary between the Fortymile River and Lake George assemblages. The map area encompasses documented porphyry Cu-Mo-Au deposits including Taurus, Fishhook (also known as SW Pika), and Pika Canyon, and is adjacent to the Fortymile Mining District. The age data in this report constrain the crystallization ages of igneous rocks and the cooling histories of metamorphic rocks in the map area and will be used to improve upon recent mapping and further refine the uplift history of eastern Interior Alaska. The complete report and digital data are available through the DGGS website: http://doi.org/10.14509/30466.