GEOPHYSICAL ACTIVITIES RELATED TO CRITICAL MINERAL MAPPING IN THE SOUTHERN MIDCONTINENT, USA

The southern Midcontinent of the United States is the nexus for several modern airborne geophysical surveys that cover more than a dozen known or prospective critical mineral systems. The effort to upgrade antiquated airborne geophysical data to modern standards began in 2014 over a portion of the Missouri iron metallogenic province and continues today as part of the congressionally mandated Earth Mapping Resource Initiative (Earth MRI). Airborne data for eight adjoining magnetic and radiometric surveys have been collected or are in progress. Once complete, the surveys will form the largest contiguous coverage of high-resolution airborne magnetic and radiometric data in the US to date. These data will form the backbone of the geophysical contribution to mapping critical mineral systems. Collaboration with the State Geological Surveys of Arkansas, Missouri, Illinois, and Kentucky as part of the Earth MRI have identified 15 focus areas that either host or are prospective for critical mineral deposits. The surveys cover areas where 16 critical minerals have been identified including Aluminum (Al), Antimony (Sb), Barite (BaSO4), Cobalt (Co), Fluorite (F), Gallium (Ga), Lithium (Li), Manganese (Mn), Niobium (Nb), Rare Earth Elements (REEs), Strontium (Sr), Tantalum (Ta), Thorium (Th), Titanium (Ti), Vanadium (V) and Zinc (Zn). Some of these commodities are being actively mined, while others have a history of production or have been identified via exploration and research. This presentation will highlight the state of the modern airborne surveys along with a complementary effort to map prospectivity for Mississippi Valley Type Pb-Zn mineralization that incorporates several different geophysical data layers. The prospectivity effort is part of the tri-national Critical Mineral Mapping Initiative (CMMI), a joint effort between the national geoscience surveys of the United States (USGS), Canada (Canadian Geological Survey), and Australia (Geoscience Australia).