Spatial geochemical trends across the coal-bearing Mesaverde Group, Colorado: critical minerals and rare earth elements

This study aims to assess the enrichment of critical minerals (CMs) and rare earth elements (REEs) in the coal-bearing sedimentary strata of the Mesaverde Group in Somerset, Colorado. Critical minerals, including REEs, are essential for emerging energy solutions and the energy transition toward a sustainable future. Previous research has documented elevated, economically viable REE enrichment (>200 ppm) in the coal-adjacent siltstone and shale intervals of publicly available cores from the Somerset coal field. Five additional cores in the area cover a similar stratigraphic interval of actively mined coal seams, but there is only limited publicly available geophysical data. This study aims to obtain high-resolution geochemical data via portable X-ray fluorescence (pXRF) and inductively coupled plasma-mass spectrometry (ICP-MS), and to develop detailed sedimentological and stratigraphic profiles across the regional core dataset. Depositional environments and facies interpretations, paired within the context of the local Colorado Mineral Belt, provide insights into potential mechanisms of REE enrichment. Preliminary data indicate that roughly 29–56% of coal-adjacent mudstone units exhibit REE enrichment >200 ppm. This new research provides a comprehensive understanding of REE enrichment within a regional case study using innovative geochemical methodologies.