Elk Creek Deposit, Nebraska
Airborne Geophysics for Rare Earth Element Deposits (AGREED) Project

Elk Creek geophysical data Elk Creek Deposit, Nebraska vertical gravity gradient (Gdd) (left, filtered to emphasize effects of buried crystalline rocks) and magnetic anomaly (right, reduced-to-pole total-field) data plots. Red dots are borehole collar locations. Black polygon is the carbonatite margin. View image at full size.

Contact: Ben Drenth, Email: bdrenth@usgs.gov

The Elk Creek carbonatite, located in southeastern Nebraska, is host to niobium (Nb)-REE minerals and covered by approximately 200 m of sedimentary cover. An airborne geophysical survey that includes gravity gradiometry and magnetic data was recently flown and provides insight into the geophysical expression of a buried carbonatite. These data have been made available to the USGS through a non-disclosure agreement with NioCorp Developments Ltd. (formerly Quantum Rare Earth Developments Corporation), which allows USGS full access to digital flight line data and to publish figures, charts, maps, and interpretations of the data. Elk Creek objectives are to:

  • develop an understanding of the magnetic and density properties of the Nb-rare earth ore and ore hosts at Elk Creek;
  • develop models of the carbonatite through integration of physical property data collected on drill core and analyses of high resolution geophysical data; and
  • develop a model that encompasses geophysical characterization of the Elk Creek carbonatite and possible geologic controls on mineralization.

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Drenth, B.J., 2014, Geophysical expression of a buried niobium and rare earth element deposit: The Elk Creek carbonatite, Nebraska, USA: Interpretation, 2(4), SJ23-SJ33. doi: 10.1190/INT-2014-0002.1

Drenth, B.J., 2013, High-resolution geophysical imaging of a north American niobium and rare earth element deposit: Preliminary results from the Elk Creek carbonatite, Nebraska: Geological Society of America Abstracts with Program, 45 (7), p. 277. Available at https://gsa.confex.com/gsa/2013AM/webprogram/Paper224356.html.

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