Earth MRI project focuses on central portion of Laramie Mountains

LARAMIE COUNTY   –   The U.S. Geological Survey started the Earth Mapping Resources Initiative, otherwise known as Earth MRI, to better understand the national availability and distribution of critical minerals. Critical mineral commodities are non-fuel materials essential to U.S. economic and national security, serve essential functions in manufacturing, and have supply chains that are vulnerable to disruption. In fact, the United States is 100 percent dependent on imports for 21 critical mineral commodities and at least 50 percent dependent on imports for 28 additional commodities. The Earth MRI program utilizes cost-shared cooperative agreements between the U.S. Geological Survey and state surveys to conduct new geologic mapping and collect new geophysical data.

The Wyoming State Geological Survey (WSGS) is participating in the Earth MRI program through a study of the central part of the Laramie Mountains in southeast Wyoming. The emphasis of the project is mapping the King Mountain and Ragged Top Mountain 7.5-minute quadrangles in Albany and Laramie counties. These quadrangles are part of the larger central Laramie Range study area.

The Laramie Range contains known but poorly understood rare earth element-enriched alkalic plutons, two anorthosite complexes, a greenstone belt, and a large mafic dike swarm. The anorthosite complexes cumulatively have potential for base- and precious-metal deposits (Cu, Ni, Au, Ag) as well as critical mineral resources (Ti, V, W, Cr, and REEs). Metavolcanic rocks of the Elmers Rock Greenstone Belt are a potential source of Ni, Cr, and Mo. Additionally, several known occurrences of graphite fall within the focus area, including the Rabbit Creek graphitic schist deposit in Platte County near the northernmost part of the study area.

This two-year project will focus primarily on geologic mapping and geochemical analyses, cumulating in the publication of two maps and a geodatabase of geochemical results.

This is also a collaborative project with several members of the University of Wyoming’s Department of Geology and Geophysics: Dr. Ron Frost, emeritus professor, who mapped much of the Laramie Range over the past several decades; Dr. Simone Runyon, assistant professor and economic geologist; and Janet Dewey, associate research scientist and analytical geochemist.

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