The Elk Creek Carbonatite located in southeastern Nebraska hosts the largest known niobium deposit in the United States. The shallower lithology of the carbonatite has been well explored by boreholes, but the deeper lithology remains poorly understood. We performed 3D joint inversion of the airborne gravity gradiometry and magnetic data collected over the area to produce structurally coupled density and susceptibility models. We carried out geology differentiation, a process of classifying the recovered physical property models into distinct units, and obtained a 3D quasi-geology model of the Elk Creek region with differentiated lithologic units. We identified 11 distinct geological units including one unit corresponding to the known niobium ore zone. We also discovered another unit with a significant volume of dense and strongly magnetized rocks below the deepest boreholes. These rocks are likely associated with unexplored niobium mineralization.

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