Helicopter time-domain electromagnetics — Newmont and the NEWTEM experience

Over the past two decades, the use of time-domain electromagnetic (EM) surveying systems, designed for an airborne helicopter-based platform, has risen in popularity. One of the first of these systems was developed and has been operated by Newmont Mining Corporation. The original system (NEWTEM I) and its more capable successor (NEWTEM II) were created to help our company explore for different types of mineral deposits, primarily gold bearing, as well as to provide general geologic mapping information in parts of the world that are often very difficult or expensive to explore otherwise. The NEWTEM system has some characteristics that have proven to be advantageous in terms of safety, cost of operation, spatial resolution, and the ability to map effectively at both ends of the resistivity scale. Our approach to the acquisition, processing, and interpretation of airborne EM data is specific to this system and to the goals of our gold-focused exploration programs. Using what is most often a locally derived helicopter, we are able to carry out a survey of whatever size our exploration program dictates and on a schedule that meets our company’s needs. Results from NEWTEM surveys have been used to identify conductive and resistive targets but more importantly to advance our general understanding of an area’s potential to host mineralization of interest to this company. We intended to provide a brief written account of the NEWTEM story for the scientific and exploration communities, including information about its design and capabilities, as well as how we process this type of data. Hopefully, this documentation will serve to inspire future developers, explorers, geoscientists, and airborne EM enthusiasts.