Geochemical data from samples collected in 2020 and 2021 for the Western Tanacross project, Tanacross Quadrangle, Alaska
Description
During the 2021 field season, geologists from the Alaska Division of Geological & Geophysical Surveys (DGGS) conducted 1:100,000-scale bedrock geologic mapping of ~2600 mi2 (~6900 km2) within the Tanacross and Eagle quadrangles. The field areas for the Western Tanacross project are approximately 20 miles north and southwest of Tok. Prospects in the region include Stibnite Creek, Tushtena, Taurus, and others. Much of the field area was mapped at 1:250,000 scale by the U.S. Geological Survey (USGS) in the 1960s (Foster, 1970). This project aims to produce more detailed and modern geologic maps and supporting datasets that will promote mineral resource exploration in eastern interior Alaska. Highlights of this DGGS western Tanacross geochemical report include precise location and sampling of the Discovery Zone, Dave's Zone, Eagle, Mosquito, North Mosquito Flats, Peternie, North Peternie, Bush, Sixtymile Butte, and VABM West prospects. Discovery Zone samples returned the highest Au values: 21ET178-4.94 ppm Au; 21ET179-2.86 ppm Au, with arsenic (As) of 42,500 ppm and 21,900 ppm, respectively. Sample 21ET178 has also elevated silver (Ag) at 14.35 ppm. Three samples from Dave's Zone returned over 1 ppm Au values: 21ET170-1.77 ppm; 21ET171-1.51 ppm; and 21ET164-1.03 ppm. Similar to the Discovery zone, those samples have high As: 9,690 ppm, 7,880 ppm, and 3,110 ppm, respectively. Sample 21ET171 has over 27 ppm of Ag. An amphibolite sample from the southern part of the Western Tanacross project, just east from Robertson River has 0.015 ppm of palladium (Pd) accompanied by 0.0027 ppm of platinum (Pt). The DGGS map area includes a section of pre-Mississippian to Permian metasedimentary and metaigneous rocks as well as Triassic to Paleogene intrusive and volcanic rocks. 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/10.14509/30844.