USGS earth mapping resources initiative (emri) project summaryproject title: geological and geochemical mapping of the REE-enriched graf phosphorite of theordovician-aged lower maquoketa formation…

This Cooperative Agreement award from the U.S. Geological Survey (USGS) under the Earth Mapping Resources Initiative (CFDA 15.073) provides $330,000 in funding to The University of Iowa to map the thickness, extent, and rare earth element enrichment of the Graf Phosphorite formation in northeastern Iowa. The project aims to generate detailed geological and geochemical maps of the Ordovician-aged phosphate deposit, which previous investigations have shown to be a potentially significant domestic source of rare earth elements. Through field sampling, rock core drilling, and geochemical analysis, the researchers will construct maps depicting the base elevation, thickness, and rare earth element concentrations of the phosphorite across a 300 square mile project area. The final technical report and maps will be made publicly available to support future academic and exploratory investigations into rare earth element resources in the central United States.

USGS earth mapping resources initiative (emri) project summaryproject title: geological and geochemical mapping of the REE-enriched graf phosphorite of theordovician-aged lower maquoketa formation in northeastern iowa, usaproject period: september 1ST, 2024 to august 31ST, 2027THE purpose of this award is to map the thickness, extent, and rare earth element (REE) enrichment of aphosphatic sedimentary rock formation in northeastern iowa. The phosphatic rock formation targeted bythis mapping project, known as the graf phosphorite, is found near the base of the ordovician-aged ( 445MILLION years old) maquoketa formation. Previous investigations of the graf phosphorite showed that IT isthicker and more enriched in rare earth elements near the northeast iowa town of dubuque than anywhereelse. The project area includes more than 300 square miles around dubuque. The maquoketa formation occurs beneath a thin veil of topsoil and glacial sediments along the rolling hillsin the dubuque area. Geologists from the iowa geological survey will collect samples of the phosphoritewhere IT is exposed at the land surface, which is typically in rock quarries, along road cuts, and streamvalleys. However surface exposures may only allow for sampling of a portion of the phosphorite. In orderto capture the full thickness of the graf phosphorite, additional samples will be collected by drilling holesinto the ground and retrieving continuous cylinders of rock core. Up to ten rock cores will be drilled atselected locations within the project area to gain a better understanding of the thickness and geochemicalvariability of the phosphorite. Each rock core will be carefully studied in order to identify the thickness andlithologic characteristics of the phosphorite across the project area. Up to 200 samples of the phosphorite, and associated phosphatic shale and dolostone, will be submitted to a laboratory for geochemcial analysis. The analytical results of these samples will help quantify the degree of rare earth element enrichment of thegraf phosphorite. This project will result in the construction of maps that show the elevation of the base of the maquoketaformation as well as the thickness of the graf phosphorite throughout the project area using existingsubsurface data from water wells and other borings in addition to the new drill core data. The geochemcialresults from this project, and previous projects, will allow for the construction of a map showing the rareearth element concentrations at each sample location. A final technical report will include maps, crosssectionsof selected locations within the mapping area, sampling methodologies, analytical results, andinterpretations. The report will be made available to the public. In order to relieve dependence on foreign sources of rare earth elements, geoscientists must conduct thefoundational research needed to identify domestic resources. This project will generate a wealth of newdata and interpretations that will benefit future academic and exploratory investigations of rare earthelement resources in the central united states.