Airborne electromagnetic imaging for critical-minerals resource assessment

Mineral resource assessments are fundamentally grounded in data - specifically data that differentiate regions prospective for a resource from those that are not. The Earth Mapping Resources Initiative is collecting baseline geophysical data over targeted areas of the United States to support upcoming critical mineral assessments. Approximately 30,000 line-kms per year of airborne electromagnetic (AEM) data are being collected as part of this effort. In the first year, surveys in Nevada, Alabama and Alaska will be carried out to inform national-scale graphite and lithium assessments. AEM surveying for graphite is one of the few cases where geophysics can directly map the resource of interest; we describe AEM surveys to be flown over two of the primary graphite resources in the nation. We also describe a regional survey focused on lithium brines and clays, where AEM models will be used to constrain deposit genesis models and to narrow the currently vast region considered prospective for lithium. We highlight aspects of the survey design and show preliminary results for those surveys that have already begun flying.