CRITICAL MINERAL EXPLORATION IN UPPER PENINSULA OF MICHIGAN: CHALLENGES AND OPPORTUNITIES

Critical minerals are non-fuel minerals essential to the U.S. economy and are at risk of supply chain disruption. In 2018, the USGS identified 35 critical minerals and, by 2022, increased their numbers to 50 minerals. Locating the presence of critical minerals as primary products has not been done for years, given that their controlling geological processes and/or their mining economics are not fully understood. Fortunately, the geological processes that enriched some of the well-studied commodities (e.g., gold and copper) also enriched some of these critical minerals. Applying research programs for critical minerals as byproducts of other principal minerals will benefit from the experiences gained from comparing to mineral assemblages for these minerals worldwide and this will increase the potential for validating the presence of critical minerals. The formation and destruction of the Earth's crust throughout its history are the primary controls on the distribution and evolution of mineral resources. The Upper Peninsula of Michigan (UP) has witnessed these enriching mineral processes from Archean to the present. The UP has the appropriate geologic and tectonic settings suited for identifying the significant minerals from different mineral systems, yet the UP's long tectonic deformation history complicates it. A thorough understanding of the geological and structural factors controlling the formation and distribution of these systems and developing holistic, scale-integrated prospectivity models are essential to increasing the identification in the UP. The proposed model consists of three stages/tasks. First, identify the different mineral systems that could be present in UP and identify the geodynamic model that controls each class. Examples include rift-related native copper deposits, rift-related magmatic copper and Ni deposits, orogenic-related deposits, and glacial placer deposits. Second, select areas to focus research efforts in the highest prospective districts. Each mineral system will have different criteria for area selection. Third, prioritize the systems for each selected area to target additional research activities in the high-prospective areas.