Assessing the precision of different geochemical methods is crucial for quantifying rare earth elements (REEs) and critical minerals (CMs) in coal-bearing sedimentary strata, with application to broader sedimentary systems. This study analyzed 230 samples via portable X-ray fluorescence (pXRF) and subsequently high-graded them for inductively coupled plasma-mass spectrometry (ICP-MS) analysis. Samples originate from the Uinta Region of Utah and Western Colorado, with lithologies including coal, claystone, siltstone, mudstone, shale, sandstone, and igneous dikes. REE quantification relies heavily on pXRF and ICP-MS datasets, but the precision between these two methods is unconstrained, encouraging the investigation into the controlling variables associated with each analytical technique. With precision as the primary objective, several sample homogeneity and spatial experiments were conducted to compare pXRF and ICP-MS datasets. Results indicate that both datasets exhibit the greatest similarity when analyzing semi-equivalent areas and volumes of samples. Across all lithologies, powdered samples consistently exhibit greater precision between pXRF and ICP-MS datasets than whole rock samples, as seen in improved r2 values. This finding supports a proposed spatial grid approach to pXRF that quantifies the homogeneity of a three-dimensional sample, resulting in data statistically similar to that of ICP-MS. Ultimately, coupled high-resolution analyses using complimentary pXRF and ICP-MS methods (recommended herein) provide the greatest understanding of REE enrichment with the objective of precision. This recommended methodology produces an unbiased pXRF dataset, 63.3%-76.7% statistically similar to that of ICP-MS. This development is crucial for the confident utilization of pXRF analysis for geochemical evaluation, especially considering domestic CM resources.

Last modified

• 01/27/2025

Creator

• Gall, Ryan
• Morris, Emma
• Free, Michael
• Fernandez, Diego
• Coe, Haley
• Fausett, Peyton
• Birgenheier, Lauren
• Vanden Berg, Michael
• Giebel, Andrew

Subject

• sedimentology
• critical minerals
• stratigraphy
• geochemistry

Identifier

• http://doi.org/10.7278/S5d-xmpj-tq44

Keyword

• Piceance Basin
• critical minerals
• precision
• Blackhawk Formation
• Uinta Basin
• pXRF
• Ferron Sandstone
• Mesaverde Group
• methodology
• ICP-MS
• energy transition
• rare earth elements

Date created

• 2022-05-23 to 2024-04-12

Source

• USGS Thesaurus

License

• Public Domain – This data is free of copyright restrictions (e.g. government sponsored data).