Ministry of Natural Resources and the Environment of the Russian Federation  
The Federal Subsoil Resources Management Agency  
«Rusgeology» JSC

Marine geological and geophysical research in the Antarctic

        Protocol on Environmental Protection to the Antarctic Treaty, that came into force in 1999, imposes a 50-year moratorium on works directly related to prospecting, exploration and extraction of minerals, but does not prohibit scientific geological and geophysical research. Such studies are intensively carried out by many states (parties to the Antarctic Treaty).

        Despite the reduction of public funding for work in the Antarctic in recent years, so far it is possible to defend the international authority of Russia in the geological community for the study of the region. Preservation of the positions won during a half-century history of the native geological and geophysical studies of Antarctica carried out by organizations of Ministry of Natural Resources of Russian Federation (formerly Ministry of Geology of USSR), is largely due to the wealth of experience of these organizations and well-functioning organizational and economic relations between them. All research in the Antarctic is carried out as part of the Russian Antarctic Expedition, under the flag of which all national activities are carried out in the Antarctic Treaty area. According to the nature of the work carried out, two main directions of geological and geophysical research developed: continental works and marine research in the ocean areas adjacent to Antarctica.

        Marine geological and geophysical studies in the marginal seas of Antarctica hold important place in the study of the ice continent structure. For the first time systematic geological and geophysical work in Antarctica was carried out by the Antarctic Geophysical Party of PMGE as a part of SAE (Soviet Antarctic Expedition) in 1980-1981 (CDP and onboard gravimetric survey), and since then they’ve been held almost annually to the present time (with the exception of the 38th Soviet and 42nd Russian Antarctic Expeditions).

        Further, starting with the 27th RAE (1982-1983), the main types of work have been and continue to be investigations by the method of the common depth point of reflected waves (CDP), seismic sounding (refracted wave method), gravimetric, hydromagnetic and geological sampling of bottom sediments in combination with seismoacoustic profiling up to 33 SAE inclusive. These methods allow solving geological problems aimed at studying the deep structure of the earth crust of the Antarctica continental margin, identifying and studying the sedimentary basins in the region-reconnaissance plan and their structure. Based on the results of the work done, it is possible to draw conclusions about the prospects of a particular region of Antarctica continental margin for minerals.

        During the work the vessels and operation technique changed. Works from the 26th to the 36th SAEs were carried out from leased diesel-electric vessels ("Captain Markov", "Vasily Fedoseev", "Captain Myshevsky", "Captain Gotsky", " Vitus Bering "," Vladimir Arsenyev "," Navarin "). Vessels were changed every year, equipment for work was placed in marine 20-foot containers and was transferred from one vessel to another.

       From the 37th RAE (Russian Antarctic Expedition), the PMGRE scientific research vessel "Academik Alexander Karpinsky" was sent to carry out marine work in the Antarctic after reequipment (Fig. 1).

Fig. 1. R/V "Academik Alexander Karpinsky"

        During the work in Antarctica the technical equipment of the R / V "Academik Alexander Karpinsky" was changing. R/V was permanently equipped with seismic hydroacustic complex HAC-120, MTS, gravity complex Cheta AГГ, differential towed magnetometer MBM-1. The on-board computer center was equipped with two integrated system computers EC-1011.

        In 2002, the seismic complex was re-equipped. The vessel was equipped with: - MSX-6000 marine recording system, a seismic streamer with a receiving base of 6000 m MSX-6000, two lines of SG-IIB pneumatic sources with a volume of 2860 dm3 produced by INPUT / OUTPUT Inc. (USA), the rear part of the R/V was reconstructed with the installation of hydraulic lifting and lowering equipment of the Norwegian company "ODIM" to accommodate the seismic streamer and two lines of pneumatic sources.

        In 2014, a comprehensive reconstruction of the R / V "Academik Alexander Karpinsky" was carried out under a state contract (a source of financing - budgetary investments). During the reconstruction work was carried out on the modernization of ship equipment and mechanisms. In accordance with modern standards and requirements for living conditions of the crew and scientific staff during long-term autonomous navigation, a part of the residential and office (laboratory) premises of the vessel was reconstructed, as well as the reconstruction of the food storage chambers.

Fig.2. Digital Seismic Recording System DigiSTREAMER

        During the reconstruction at the R / V "Akademik Alexander Karpinsky", a new integrated system for collecting marine seismic data DigiSTREAMER ™ 2D, consisting of a DigiSTREAMER recording complex complete with DigiSREAMER towed seismic streamer, allowing seismic studies in complex marine conditions, was installed. The onboard equipment is intended for seismic streamer control, and recording of seismic data; it allows to conduct on-line quality control of the received material. Outboard equipment is a seismic solid state (with gel filling) streamer with built-in hydrophones (groups of hydrophones) for recording seismic signals, towed behind the stern of the ship, the maximum length is 8000 km (640 channels).

Fig. 3. Seismic streamer DigiSREAMER 8000 m

        Also, equipment was purchased to enable the seismic complex to significantly improve the positioning accuracy of the vessel and the outboard equipment, and improve the quality of the data: a system for monitoring, testing and controlling the deepening devices PCS SYSTEM 3 and a set of seismic digging devices (such as DigiBird 5010 and DigiBird 5011E), allowing to control the position of the streamer in depth; a system for positioning the 2D seismic streamer tail buoy (Seatex Seatrack 220 satellite receiver); navigation complex ORCA 2D, designed to control the seismic work and collection of the navigational data and data on position of the outboard equipment during 2D seismic survey (a software license can be purchased on a lease basis for a period of work).

        To ensure the operation of the SG-IIB pneumatic sources of the seismic complex, new high-pressure compressors SAUER WP 6442 are installed.

        DigiSREAMER seismic streamer.
        The outboard part of the differential sea magnetometer SeaSpy 2
        On-board gravimetric complex consisting of two gravimeters "Chekan AM"

Fig. 4. The outboard part of the differential marine magnetometer SeaSpy-2 and Fig. 5. The on-board gravimetric complex, consisting of two gravimeters "Chekan AM"

       To extend the methodological possibilities of using R/V during geological and geophysical studies, the following equipment is additionally installed: - navigation and bathymetric complex (multi-beam sounder) ATLAS HYDROSWEEP MD / 30 1.5 ° х1.5 ° (with a set of high-precision detection and recording of the course, roll, pitch and heave displacement Teledyne TSS MAHRS) and a set of bottom geological sampling equipment.

Fig.6. ATLAS HYDROSWEEP MD / 30 multi-beam sounder operator station

Fig.7. Winch for bottom geological sampling

        Also, new software (ProMAX 2D (ProMAX / SeisSpace 2D), LMKR GeoGraphix, Geosoft Oasis montaj) was installed within the reconstruction program to process seismic and gravimagnetic data, and the computer hardware of the on-board computer center was updated.

        The implementation of the reconstruction program made it possible to create on the basis of the R/V "Akademik Alexander Karpinsky" a modern multipurpose geological and geophysical vessel capable of providing a high level of seismic work using the methods of CDP, RWM, WDSP, gravimagnetic and geological studies of continental margins in the Arctic and Antarctic, and to extend the period of effective ship operation. The reconstruction carried out significantly increased the geological and geophysical information content of research and safety of offshore operations and ensured compliance with the requirements of the Protocol on Environmental Protection to the Antarctic Treaty of 1959.

        Over the past years, the geological structure of sedimentary basins of the Indian Ocean area of the Antarctic has been studied by the regional reconnaissance network of profiles: - the Lazarev Sea, the Cooperation Sea, the Riiser-Larsen Sea, the Cosmonauts Sea, the Davis Sea and the d'Urville Sea.

        The Indian Ocean area of the Antarctic includes the shelf, the continental slope, the foot of the continental slope, the abyssal basins and the southern part of Kerguelen Plateau (Figure 0.1). Some sectors of this area were named marginal seas. These include: the Riieser-Lersen Sea (14 ° -34 ° E), the Cosmonauts Sea (34 ° -54 ° E), the Cooperation Sea (54 ° -82 ° E), the Davis Sea (87 ° -97 ° E), the Mawson Sea (96 ° -113 ° E), the d'Urville Sea (136 ° -148 ° E, Atlas of the Antarctic, 1966).

Fig.8. The studied sector of the continental margin of Antarctica

        The Indian Ocean is the most studied part of the Southern Ocean. Here, under the supervision of PMGE and with the participation of VNIIOkeangeologia specialists, the reconnaissance stage of the works was completed by the PMGE. Own set of geophysical (primarily seismic) materials allows a detailed description of the sedimentary basins of this region. The length of the studied water area in latitude is about 6,500 km, and its total area exceeds 4.5 million km2.

Fig. 9. Network of regional reconnaissance profiles performed by JSC "PMGE" in the Indian Ocean area of Antarctica

         The Indian continental margin of Antarctica and adjacent basins were formed as a result of rifting, oceanic spreading and subsequent submersion of the Earth crust during the late Mesozoic and Cenozoic. These processes led to the formation of large sedimentary basins with a thickness of sedimentary cover up to 7-8 km, which, according to preliminary estimates, have high oil and gas prospects.

Fig. 10. Sedimentary basins of the Indian Ocean continental margin of Antarctica

        In the studied sector of the Antarctic, three large sedimentary basins can be distinguished; each of them has specific features of development (especially in the rift and early post-rift stages): the Riiser-Larsen Sea basin, the Cosmonauts Sea, Cooperation Sea, Davis Sea basin, and the basin located in the sector from the Mawson Sea to the d'Urville Sea (hereinafter referred to as the Mawson-d'Urville Sea Basin). The basins include continental margins and southern parts of their oceanic hollows.

        Complex interpretation of geophysical data obtained in the Indian Ocean area of the Antarctic allows one to approach many fundamental problems of the evolution of passive continental margins, the development of oceans and volcanic plateaus. Such problems include: the dynamics of extreme stretching of the Earth crust and the penetration (opening) of the continental mantle; identification of the continent-ocean boundary, stability of seabed spreading in conditions of ultra-slow oceanic opening, character and volume of magmatism of non-volcanic margins; nature of the volcanic plateau crust; mechanisms for the invasion of asthenospheric plumes (hot jets)

Fig. 11. The section of the earth's crust on the continental margin of Antarctica (the Cooperation sea).

In the short term, marine geological and geophysical research is planned to be carried out within the framework of the State program in the Pacific sector of the western Antarctic.

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