Tectonic and Metallogenic Evolution of the Yukon-Tanana Upland, Alaska

Science Center Objects

The Yukon-Tanana upland in eastern interior Alaska is a geologically complex block containing deposits of base-metal, platinum-group-element, and gold-silver-copper mineralization. It also hosts numerous mineral systems that are known or suspected to contain critical minerals.

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Scientist examining outcrops of strongly deformed and metamorphosed rock, Divide Mountain, Yukon-Tanana, eastern Alaska

USGS scientist examining outcrops of strongly deformed and metamorphosed rock along Divide Mountain in the Yukon-Tanana upland of eastern Alaska.
(Credit: Jamey V. Jones III, USGS. Public domain.)

This multi-year study focuses on the geologic, metallogenic, and geophysical framework of the broader Yukon-Tanana upland in east-central Alaska. The project builds on a strong legacy of previous and recent USGS work in eastern Alaska and involves close collaboration with the Alaska Division of Geological and Geophysical Surveys (DGGS) and Canadian counterparts in the Yukon Geological Survey and Geological Survey of Canada. The area of interest extends from the western Tanacross and Eagle quadrangles to the Fairbanks area. The area includes two producing gold mines, multiple mineral districts, and numerous deposits and prospects that are the focus of active mineral resource exploration. All known or suspected mineral systems in the region have the potential for associated critical mineral enrichments. This project coordinates with systematic geological mapping and geophysical surveys conducted by DGGS under the USGS Earth Mapping Resource Initiative so that we fully capitalize on all available resources and thoroughly characterize the tectonic, magmatic, structural, geochemical, isotopic, and metallogenic evolution of one of Alaska’s important mineral belts.

 

Current Activities

Geologic Framework

Contact: James V. Jones III, jvjones@usgs.gov

Geologic framework studies involve regional geological mapping, bedrock exhumation and landscape evolution studies, and associated analytical work (for example, geochronology, thermochronology, petrology, geochemistry) across the entire Yukon-Tanana upland. Research includes igneous, metamorphic, structural, and thermochronologic studies. This work is integrated with geophysical and metallogenic tasks described below to provide comprehensive constraints on the tectonic evolution of the region and framework geological controls on its mineral endowment.

Scientist digging in tundra to find bedrock for geochemistry and geochronology sampling, Yukon-Tanana upland, eastern Alaska

USGS scientist digging through tundra in hopes of finding bedrock to sample for geochemistry and geochronology, Yukon-Tanana upland, eastern Alaska.
​​​​​​​(Credit: Jamey V. Jones III, USGS. Public domain.)

Metallogenic Framework

Contact: Douglas C. Kreiner, dkreiner@usgs.gov 

Metallogenic framework studies involve delineation of prospective mineral systems across the region and geological mapping of key mineral occurrences and deposits in the study area.  Comprehensive analytical methods (for example, geochronology, geochemistry, radiogenic and stable isotopes) are combined with geological observations to characterize mineralization and to relate it to the geological context and tectonic environment(s) in which it formed.

Exploration Geochemistry

Contact: Karen Kelley, kkelley@usgs.gov

Use of indicator mineral and hydrogeochemistry exploration techniques to explore for concealed or hidden mineral systems beneath the extensive alluvial/colluvial cover in the region. This research also involves placer gold fingerprinting studies to assess how distinct mineralogical, mineral chemistry, and geochemical signatures in sediment, placer gold (heavy mineral concentrates), and water reflect different deposit types in the upland.

 

Geophysical Framework

Contact: Ben Drenth, bdrenth@usgs.gov

Geophysical framework studies involve strategic planning of new, high-resolution airborne magnetic and radiometric surveys throughout the region together with synthesis and modeling of existing geophysical data. Processing, interpretation, and integration of new data with existing data compiled across the international border will inform geological and metallogenic mapping and modeling throughout the region.

 

Completed Activities

Tectonic and Metallogenic Evolution of the Eastern Yukon-Tanana upland, Alaska

Alaska/Yukon Geophysical/Geological Reconciliation of the Pericratonic Yukon-Tanana Terrane

These two previous projects focused on the easternmost part of the Yukon-Tanana upland adjacent to the Alaska-Yukon border. This research involved integration of geological, metallogenic, and geophysical data in the Tanacross and Eagle quadrangles of eastern Alaska to address cross-border correlation of geologic units, litho-tectonic assemblages, and metallogenic domains.