Example 1. Siberia. Mapping of a manmade talik
formed in permafrost by injection of highly saline mine drainage from a diamond mine.
TEM soundings were applied to map a manmade talik (unfrozen rocks) formed in permafrost by injection of saline diamond mine drainage for disposal. Figure 1 shows locations of TEM stations, profile traverses a cluster of injection wells.
Surveys were run using a 100 m × 100 m transmitter loop and induction receiver coils with a 200 kHz bandwidth and an effective area of 400 m2. Slingram configuration with a 78 m transmitter-receiver offset was undertaken to eliminate strong IP effects at the in-loop configuration to polarity reversal. Transmitter current was maintained at 16-19 A. The transmitter and receiver were GPS synchronized.
High-quality data were collected due to properly chosen sounding strategy and loop configuration, in spite of strong EM noise from a power line (a few kV) feeding the diamond mine located between stations 3 and 4. The acquired data were processed in TDEM Geomodel.
The resistivity model obtained by TDEM Geomodel inversion of TEM data (see Fig. 2 for the section and Fig. 3 for its geological interpretation) provided constraints on the size and geometry of the talik and made basis for recommendations to improve operation of mine drainage injection wells.