Northeast Tanacross geologic map and map units and descriptions

Report of Investigation 2020-9B, Northeast Tanacross geologic map and map units and descriptions, provides 500 square miles of 1:63,360-scale geologic mapping in the northeastern Tanacross Quadrangle (Tanacross D-1, and parts of the C-1, C-2, and D-2 quadrangles), located 15 miles southeast of Chicken, Alaska. The project took place during two periods: a reconnaissance mapping effort June 12-22, 2017, and a detailed campaign June 18-July 16, 2018. The map area covers the boundary between the allochthonous Yukon-Tanana terrane (YTT) and the parautochthonous North American margin (pNA) from which the YTT initially rifted. This suture zone has a complex, multiphase structural and metamorphic history, and the northeastern Tanacross Quadrangle is one of the rare areas in which it is exposed. The conceptual framework has been developed in the literature, but it is not fully represented in previously published geologic maps of eastern Alaska. This map encompasses an area of current mineral industry interest; it includes the Taurus porphyry copper-gold-molybdenum +/- rhenium deposit and several other occurrence types, including gold, copper, and molybdenum in porphyritic intrusions, structurally controlled silver-lead-zinc prospects, and placer gold deposits. The complete report, geodatabase, and ESRI fonts and style files are available from the DGGS website: http://doi.org/10.14509/30539.