30-9 Integrated Geophysical and Structural Analysis of Critical Mineral Potential in Northeastern Washington State

Session: Geological and Geochemical Investigations of Critical Minerals in New Mexico and Beyond, and Technological Advances in Extraction of Critical Minerals

Presenting Author:

Authors:

Abstract:

Northeastern Washington State is a product of the collision and breakup of supercontinents, accretion of ancient terranes, rifting, and development of metamorphic core complexes. Washington’s oldest rocks are Proterozoic metasedimentary units from the accretionary belt of Rodinia. After Rodinia broke up in the Neoproterozoic, multiple terranes were accreted onto the western margin of Laurentia. The Siletzia Terrane was accreted in the Paleocene-Eocene, and subduction briefly ceased. At this time, two metamorphic core complexes formed in northeastern Washington, the Kettle Dome and the Okanogan Dome. Clearly, northeastern Washington’s diverse geology has been subjected to prolonged and intense thermal events. The exposed basement and accreted terranes in the Republic Graben region have been historically mined for various commodities, particularly gold. The economic viability of geologic units in this region and associated tectonic evolution, as well as the history of mining, indicate that Northeastern Washington is an ideal target for identifying and quantifying critical mineral resources to enhance modern domestic supply.

The focus of the U.S. Geological Survey Earth Mapping Resources Initiative (EarthMRI) high-resolution geophysical data acquisition and geologic analyses is to better understand critical mineral resources within the United States. Towards that end, we present several new geologic datasets, including pXRF geochemical analyses to constrain elemental abundances, and low-temperature thermochronology (apatite and zircon U-Th/He) to constrain the thermal history. We integrate several of these datasets, regional geologic maps, new and legacy gravity data and EarthMRI high-resolution aeromagnetic and radiometric datasets to create a heatmap of potential critical mineral resources. We compare the heatmap results with pXRF measurements from geologic samples collected in regions of “higher” and “lower” critical mineral favorability. This comparison demonstrates initial agreement between modeled favorability and measured geochemistry for some elements, such as tungsten and manganese. Ongoing and future work will integrate geologic and geophysical datasets through a suite of thermo-kinematic and geophysical models to constrain the crustal structure and tectonic history across Northeastern Washington. These model results will help resolve exhumation rates and magnitudes along major fault systems and intrusive complexes, interactions with preexisting geologic units and basement rocks, and may ultimately be used to predict critical mineral potential at depth.

© Copyright 2026 The Geological Society of America (GSA), all rights reserved.