Time‐domain electromagnetic survey for gold exploration, Nevada

Geophysics ◽  
1997 ◽  
Vol 62 (5) ◽  
pp. 1409-1418
Author(s):  
Hasan Kâmil Aktarakçi ◽  
Norman Harthill ◽  
Mark W. Blohm

A time‐domain electromagnetic (TDEM) sounding survey was carried out on the western basin‐range boundary of Smith Creek Valley, Nevada. The survey achieved its goal of mapping depth to volcanic basement along five traverses that crossed the boundary. In addition to mapping the electrical basement, the TDEM survey outlined significant cross faulting within the alluvium. Seventy five soundings were made over a five day period using a Geonics EM37 system that shows the usefulness and effectiveness of the TDEM technique to determine depth to electrical basement under heterogeneous range‐front alluvium.

2021 ◽  
Vol 11 (5) ◽  
pp. 2060 ◽  
Author(s):  
Alexander Parshin ◽  
Ayur Bashkeev ◽  
Yuriy Davidenko ◽  
Marina Persova ◽  
Sergey Iakovlev ◽  
...  

Nowadays in solving geological problems, the technologies of UAV-geophysics, primarily magnetic and gamma surveys, are being increasingly used. However, for the formation of the classical triad of airborne geophysics methods in the UAV version, there was not enough technology for UAV-electromagnetic sounding, which would allow studying the geological environment at depths of tens and hundreds of meters with high detail. This article describes apparently the first technology of UAV-electromagnetic sounding in the time domain (TDEM, TEM), implemented as an unmanned system based on a light multi-rotor UAV. A measuring system with an inductive sensor—an analogue of a 20 × 20 or 50 × 50 m receiving loop is towed by a UAV, and a galvanically grounded power transmitter is on the ground and connected to a pulse generator. The survey is carried out along a network of parallel lines at low altitude with a terrain draping at a speed of 7–8 m/s, the maximum distance of the UAV’s departure from the transmitter line can reach several kilometers, thus the created technology is optimal for performing detailed areal electromagnetic soundings in areas of several square kilometers. The results of the use of the unmanned system (UAS) in real conditions of the mountainous regions of Eastern Siberia are presented. Based on the obtained data, the sensitivity of the system was simulated and it was shown that the developed technology allows one to collect informative data and create geophysical sections and maps of electrical resistivity in various geological situations. According to the authors, the emergence of UAV-TEM systems in the near future will significantly affect the practice of geophysical work, as it was earlier with UAV-magnetic prospecting and gamma-ray survey.


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