We present the most informative results of archeological and geophysical field studies of the Baraba forest–steppe over the last three years. The studies of the archeological sites of different types belonging to a wide time interval (~6000 BC–2000 AD) were carried out. Data on the presence, size, and configuration of archeological objects were obtained by magnetometry and electrometry. We studied contrast between the magnetic properties of the upper horizon of present-day soil and underlying substratum at archeological sites of different types and ages. Low contrast reduces amplitudes of magnetic anomalies above buried ancient structures. It has been shown that geoelectric methods are efficient in cases when magnetometry is not.

The importance of pre-excavation permafrost detection within ancient burial mounds in the Altai by geophysical methods is hard to overestimate. There was no way of detecting small quantities of frozen ground or ice under stone mounds, and this is a topical issue in Russian archeology. Frozen mounds, which retain organic matter owing to natural processes, are an exceptional source of information about historical and cultural processes in the Early Iron Age. Pre-excavation geophysical prospecting is especially important in the context of global warming, which might destroy a whole layer of cultural and historical information. The integrated geophysical studies conducted in recent years focused on a group of archeological sites of the Pazyryk culture whose burial constructions are very likely to contain frozen artifacts. As a rule, such burial mounds are located at a considerable altitude and contain permafrost, which creates unique conditions for the preservation of artifacts. Such localities include the Ukok high plateau (southern Altai) and the northwestern part of Mongolian Altay. Systematic field studies were conducted on the Ukok Plateau in 2003 and 2007 and in the adjacent territory of Mongolian Altay in 2005 and 2006. The following geophysical methods were used: vertical electrical sounding (VES), electrical tomography (ET), shallow frequency scanning, georadiolocation, magnetic susceptibility measurements, gamma-ray spectrometry, and chromatography. The field works were planned with a heavy reliance on the 3D mathematical simulation of electric and EM fields, which is meant for a realistic estimate of the possibilities of geoelectrics and the best ways of its application to burial-mound studies and data interpretation. The excavations conducted in 2006 in northwestern Mongolia within the Altai Mts. confirmed the geophysical prediction of permafrost at all the sites identified by the geophysical studies in 2005. In one of the mounds, they yielded a unique intact tomb of a Scythian warrior.

This paper presents an extensive review of currently available shallow-depth portable geophysical instrumentation for electromagnetic induction sounding and profiling and the main technical characteristics of the devices. A new ground-based multicoil shallow-depth device with a special arrangement of receiver coils is considered. The latter are placed on the line where the vertical component of the magnetic field from the source coil is zero. The spacing between the source and the receivers is used as a sounding parameter, along with a frequency. This increases the efficiency of the study of the upper section and the contrast between the sounding curves, which simplifies their interpretation. In studies of local anomalous objects, the use of the proposed method and instrumentation significantly improves the quality of geophysical data. The increase in sounding efficiency provided by these devices is demonstrated on both synthetic and real field data.

In this paper, we describe a setup for modeling hydrate-bearing rock samples and measuring their electrical resistivity at different pressures and temperatures using an AMNB cylindrical four-electrode probe. Methods for modeling hydrate-bearing rock samples and measuring their resistivity are considered. The setup was used in a series of experiments to measure the resistivity of sand samples containing water, ice or tetrahydrofuran (THF) hydrate. It is shown that when the rock pores contain hydrates and a partially unfrozen aqueous solution of NaCl and THF, the electrical resistivity is determined by the high resistivity of the solution and increases with the formation of hydrate. The presence of THF hydrate in the experimental samples increased their resistivity by 180–320 Ohm·m at a temperature of about 0 °C. After the formation of hydrate and freezing of residual water, the resistivity of the sample is stabilized at 70–80 Ohm·m at a temperature of -15 °C.

As a result of experimental work, the linear nature of the temperature drift in the AEMP-14 equipment was established. The temperature coefficient of the resistivity readings depends on the measurement frequency, but does not depend on the signal level. A method for eliminating the temperature drift of the device is proposed. Temperature dependence introduces a deviation from true electrical conductivity within 1–12 % at 20 °C. This method minimizes the error in the measured values.