Example 1. Siberia. Mapping of a manmade talik
formed in permafrost by injection of highly saline mine drainage from a diamond mine.

Objectives:

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.

Location of TEM profile
Fig. 1. Location of TEM profile.

Method:

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.


Results

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.

resistivity model obtained by TDEM Geomodel inversion of TEM data
Fig. 2. Resistivity model obtained by TDEM Geomodel inversion of TEM data.

interpretation of TEM data in terms of permafrost conditions
Fig. 3. Interpretation of TEM data in terms of permafrost conditions.