Ministry of Natural Resources and the Environment of the Russian Federation  
The Federal Subsoil Resources Management Agency

Aerogeophysical research in Antarctica

        For many years, the Polar Expedition as part of the Russian Antarctic Expedition regularly carries out aerogeophysical work in East Antarctica. The relevance of this type of research is due to the well-known matter that the overwhelming majority of the Antarctic continent is an ice dome, and to receive any information about what is under the glacier is possible mainly by remote methods, in particular, by means of aeromagnetic and radar surveys. Measurements of the anomalous magnetic field make it possible to obtain data on the magnetic properties of glacier-covered rocks, the size and mode of occurrence of magnetic objects, and to draw conclusions about their nature and the history of geological development of the territories. By means of radar it is possible to "enlighten" the glacier and obtain data on its internal structure and thickness of the ice layer, and, knowing the latter, to build up the relief of the ice surface. This information can be used for glaciological and geomorphological constructions, for understanding the orographic and neotectonic processes occurring here.

        Since the 80s of the last century aerogeophysical studies conducted by the Polar Expedition have been concentrated in the sector between 62 ° and 88 ° E, including Mac.Robertson Land, and Princess Elizabeth Land. The work was carried out using Il-14 and An-2 aircraft based at the ice airfields of the Union and Druzhnaya-4 bases and the Progress wintering station. During this period, the integrated aerogeophysical survey (magnetometry and radiolocation of glaciers) of scale1: 200 000 - 1: 500 000 covered an area of more than 600 000 sq. km (Figure 1). As a result of these works, such large structures of the continental part of Antarctica Earth crust as the Lambert-Amery rift zone and "Gaussberg tectonic activation zone" are completely mapped.


Fig. 1 State of exploration by aerogeophysical studies of East Antarctica in the Lambert-Amery glacier region, the Prince Charles mountains, the Vestfold oasis and their margins

        Beginning with the season of the 62nd RAE (2016-2017), the Polar Expedition moved the exploration area eastward and proceeded to systematic aerial survey in the sector between 88 ° and 102 ° E, including Kaiser Wilhelm II Land, Queen Mary Land and the Wilkes Land (Figure 2). According to a contemporary view, this area is part of Scott's rift system, which is completely unexplored by Russian researchers. In addition, the planned work will allow a detailed study of the northern articulation area of the above-mentioned rift system and the Golitsyn subglacial mountains. The latter, in addition to being of interest from the standpoint of tectonics, neotectonics and deep structure, are important in terms of studying the history of glaciation of East Antarctica as a whole, since according to present view, this region, as well as the subglacial mountains of Gamburtsev, was once the center of the formation of glaciation, which subsequently led to formation of the East Antarctic ice sheet. The area of planned research is of considerable interest in terms of understanding the deep structure and evolution of East Antarctica, starting from the early stages of its formation in the Archean, transformations in the Proterozoic and Paleozoic, the early history of the Gondwana disintegration and the changes in the natural environment of the Antarctic in the Cenozoic.

Fig. 2 Perspective plan for the development of aerogeophysical research in East Antarctica for 2018-2023.

        As an aerogeophysical equipment carrier, an An-2 (An-3) aircraft is supposed to be delivered to Antarctica on board the R / V "Akademik Fedorov" and during seasonal operations it will be based at the icefield of the Mirny station. To measure the induction of the magnetic field, the CS-L sensor (Scintrex, Canada) is rigidly attached to the outboard bar behind the tail unit of the aircraft (Figure 3).

The main characteristics of the magnetic sensor CS-L:

- magnetically sensitive block - quantum, cesium, single-chamber;- sensitivity - 0.001 nT;
- systematic error - no more than 2.5 nT on the entire operating range-
- random error - no more than 0.002 nT-
- measurement cycle - 0.1-1.0 s;
- measuring range - 15 000-105 000 nT;

Fig. 3 An-2 aircraft with installed magnetic sensor at the ice station Mirny

        To probe the glacier a unique ice locator RLС-130 (LLC "UHF-Radio Systems", SPb), specially designed and manufactured to the order of the Polar Expedition, with the following main parameters:

- working frequency - 130 MHz;

- peak pulse power, not less than - 200 W;

- the duration of the probing pulse - from 0.5 to 15 μs;

        The coordination of the An-2 aircraft in flight and the alignment of measurement points on the plan were based on the GPS satellite navigation system, for which the SveeEight receivers (Trimble) were integrated into the recording complexes. According to the control parking observations at the airfield, the positioning error of the aircraft on the route does not exceed ± 6 m in both plan and height. All flight information (time, geographical coordinates, height relative and absolute by GPS, value of the module of the complete geomagnetic field vector, tracks of temporary radar sections) is registered digitally in the on-board computers (Fig. 4).

Fig. 4 Aerogeophysical equipment aboard the An-2

        The result of complex aerogeophysical studies is the compilation of sets of geophysical and interpretation maps of scale 1: 500 000 - 1: 1 000 000, including maps of scale 1: 500 000 of anomalous magnetic field in graphs and isolines, hypsometric curves of subglacial topography, isolines of ice cover thickness and structural-tectonic Scheme 1: 1 000 000 New magnetometric and radar data supplement the information database for the scientific forecast of the mineral resource potential of this region of Antarctica, and also form the basis for generalized maps (Fig.5) and atlases of Antarctica within the framework of international projects ADMAP and BEDMAP.

Fig. 5. Scheme of demarcation of the placer rock bed of Mac.Robertson Land and Princess Elizabeth Land by altitude

Areas located in the altitude range: 1 - from 1000 m to 2000 m; 2 - from 500 m to 1000 m;3 - from 150 m to 500 m; 4 - from -300 m to 150 m; 5 - from -900 m to -300 m; 6 - below -900 m; 7 - the water area of the Ocean, and ice shelves; 8 - coastline and boundary of ice shelves according to [ADD, 2016]; 9 - outcrops of rocks by [ADD, 2016].

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