• 2023-07-07

Case study Goldspot

Author: Derek Kouhi - Goldspot

GoldSpot Discoveries Corp. specializes in the mineral exploration industry and prides itself on using data-driven science, artificial intelligence, and machine learning to get more information out of data. The Applied Geophysics team at GoldSpot focuses on the acquisition of airborne geophysical data with the use of their Multi-Parameter Acquisition Survey System (MPASS), which is a helicopter-bourne system capable of collecting magnetic, magnetic gradiometry, very-low-frequency electromagnetic (VLF-EM), radiometric and LiDAR data.

The radiometric component of the MPASS system utilizes a Medusa MS-4000 AGRS detector for high-resolution radionuclide detection at approximately 80 m AGL survey heights. Radiometric data can play an essential role in the mineral exploration industry by delineating regional geological units, as well as more localized alterations in the rock due to varying concentrations of K, Th, and U nuclides.

Recent MPASS surveys were conducted in Arizona and Nevada, USA, using the MS-4000 and Medusa’s full-spectrum analysis (FSA) processing. Surveys were conducted over rugged desert terrain with the detector installed in a helicopter, flying from 50 m to 350 m AGL. This presented the challenge of acquiring reliable counts from ground sources and applying FSA height corrections at clearances well over the standard 160 m threshold. Data was collected on a flown drape surface with survey lines spaced at 100 m with 50 m spaced infill lines where higher resolution was necessary. The primary objective of the surveys was to aid in geological mapping and better define lithological units and structures for gold exploration.

MS-4000 Medusa gamma-ray spectrometer
Goldspot maps

Radiometric results from a survey flown for Elevation Gold Mining Corp. are shown in the form of a ternary image in Figure 2. In exploration geophysics, the ternary image is often used to display a complete picture of the radiometric signal in the area by combining the potassium, uranium, and thorium components into one map. Different rock types will have varying mineral compositions and, therefore, differing concentrations of each of the three radionuclide components, making radiometric surveying a powerful tool in the industry. In this example, the ternary image clearly shows an excellent correlation between locally mapped lithological and structural contacts and the high-resolution radiometric data. In addition, flying heights ranging from 160 to 350 m AGL have produced good results with seamless continuity with the rest of the data.

In conclusion, the Medusa MS-4000 detector is a key component of the MPASS system at GoldSpot and provides valuable insight as a stand-alone product in the mineral exploration industry and excels even further when paired with magnetic, VLF, and LiDAR acquisition.