This data release presents portable X-ray fluorescence (pXRF) data and physical properties (grain density, saturated bulk density, dry bulk density, and magnetic susceptibility) of 30 rock samples collected from an Earth MRI survey area in northeastern Washington, USA. Rock type information (age and lithology) are also included. The rock samples were initially collected for low-temperature thermochronology in May and June of 2025 and are composed mostly of felsic igneous or metamorphic rocks, many of which are Triassic-Eocene in age. The pXRF analysis is part of a larger project to determine the tectonic context and critical mineral potential of northeastern Washington State through structural and thermo-kinematic modelling.
The 30 samples represented in this data release are also being processed and analyzed for low-temperature thermochronology (apatite helium and zircon helium). The thermochronology results will be used in thermal models to determine the tectonic deformation history, age and rate of faulting, erosional exhumation, and ultimately timing and process of critical mineral formation. The pXRF data will be used to constrain the model based on the presence and location of critical mineral resources at the surface. The results from these subsequent analyses and modeling will be published separately at a later date.
The pXRF data presented here were collected in December 2025 using instrumentation housed in the Bascom Laser Diffraction Sedimentology Laboratory at the USGS Florence Bascom Geoscience Center (FBGC) in Reston, VA.
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