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Mykola Yakymchuk, National Academy of Science of Ukraine (Ukraine)
Sergiy Levashov, MMC IGS NAS Ukraine (Ukraine)
Ignat Korchagin, Institute of Geophysics of Ukraine National Academy of Science (Ukraine)
Valery Solovyov, Institute of Geophysics of Ukraine National Academy of Science (Ukraine)
Yuriy Kozlenko, Institute of Geophysics of Ukraine National Academy of Science (Ukraine)
Vladimir Bakhmutov, Institute of Geophysics of Ukraine National Academy of Science (Ukraine)
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During last years the geodynamics of Drake Passage and Bransfield Strait region has been actively studied. New geological and geophysical data that have been obtained for bottom structures of West Antarctica are of particular importance for evolution and geodynamics processes of this region understanding. Geophysical surveys near Antarctic Peninsula enabled to specify the inner structure of some blocks of Drake Passage, Bransfield Strait and continental margin. This analysis has been provided new data of the sedimentary horizons deep structure and Moho crust-mantle discontinuity that is a strong and continuous reflector of Drake Passage. Obtained crustal inhomogeneities could be connected with some evolution stages of Antarctic Plate, Drake Passage and magmatic processes of Bransfield Strait.
The Ukrainian Antarctic expeditions acquired new geoelectrical data along profiles across Drake Passage and along Bransfield Strait, Antarctic Peninsula, with the aim of studying the crustal structure of these features down to depths of 32 km. The electromagnetic experiments yielded a new dataset containing potentially valuable information about the internal crustal structure of Drake Passage and Bransfield Strait. New estimates of the depth of the Moho discontinuity in these areas were obtained. Modelling experience of deep crust structure by geophysical data shows that there is a possibility to investigate the fluid regime, tectonic disturbances and crush zones in basement and local places of submarine volcanic activity too. We also observe that the location of submarine volcanic structures in Bransfield Strait appears to be given by geoelectrical data.
Similar results obtained by three different methods (gravity and magnetic surveys, vertical electric-resonance sounding) during Ukrainian Antarctic expeditions in 2004-2006 years assure the notable magmatic dynamism of Bransfield Trough that forms in the conditions of structural transformations and rifting processes migrating NE-SW along Bransfield Strait.
The new geophysical data allow investigation of the deep crustal structure in a region where possible mantle diapirs have been emplaced into the pre-rift continental complexes of Bransfield Strait Therefore this region is interesting not only from the viewpoint of studying processes of multiphase expansion in Mesozoic, but also as an area of young tectono-geodynamic processes (2.5?4.0 Ma) accompanied by the formation of multiple volcanic uplifts and ridges composed of different basalts.. Newly interpreted values of the depth to Moho confirm the tectonic view of Bransfield Strait as a modern rift basin with anomalous crust.
The evolution of the deep diapir was accompanied by rift-related intrusion into the continental Paleozoic - Mezozoic blocks This has had a major impact on the geodynamic processes in the region.
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